Download conceptual flow chart of the microbiology unit (college level) microbes

CONCEPTUAL FLOW CHART OF THE
MICROBIOLOGY UNIT (COLLEGE LEVEL)
MICROBES
MICROBIAL
ARCHITECTURE
LESSON 1
MICROBIAL
ECOLOGY
Lesson 2
MICROBIAL
PHYSIOLOGY
Lesson 3
MICROBIAL
PATHOLOGY
Lesson 5
MICROBIAL
LIFE CYCLES
Lesson 4
OVERVIEW OF THE COLLEGE LEVEL MICROBIOLOGY UNIT
The scientific discipline that deals with the study of microorganisms or microbes is called Microbiology. There
are many microbes that are studied which include the Kingdoms Monera (Bacteria), Fungi (Mushrooms and
Yeasts) and Protista (Protozoa). Another type of microbe are Viruses which are not living particles, but need
the living metabolic machinery of living cells in order to replicate.
This College level Unit in Microbiology explores microbes on five levels, their architecture, ecology, physiology,
lifecycles and pathology. Students will be given an interactive tour of the world of microbes and learn more
about their impact on Humans, animals, plants and on the environment in general. They will become aware of
pathogenic (harmful) and non-pathogenic (helpful) microbes and develop an understanding of how
microbiologists devise methods to study microbes in order to understand their benefits and to help to minimize
their deleterious effects.
SECTION 2: LESSON BY LESSON PLANS
Lesson #1: THE ARCHITECTURE OF MICROBES
EXPECTATION
CODES
EXPECTATIONS
MBV.01
Students will demonstrate an understanding of the anatomical characteristics
of various species of microorganisms from the Kingdoms Monera, Protista,
and Fungi. They will also investigate the structures of Viruses (a category
and not a Kingdom) and the T4 bacteriophage.
MBV.02
Students will use a variety of methods (e.g. microscopy, TEM and SEM
analysis, models and drawings in order to deconstruct the structure of
representative species from the Kingdoms Monera, Protista and Fungi and
from the category Viruses. They will also study the design of various
structures of these species in order to understand how "form is related to
function"
MBV.03
Students will analyse the role of representative microbes in technology
especially how they are utilized in genetic engineering (e.g. splicing the
human gene that codes for insulin production into bacterial DNA in order to
produce insulin in vast quantities for commercial production in the
pharmaceutical/bioengineering industry. Students will also assess the impact
of some of the principles of Genetic Engineering and biotechnology on
society.
MB1.01
Students will compare the basic anatomical and biochemical characteristics
of the genetic material (DNA and RNA) of Monera (Archaea and Eubacteria)
and Viruses. They will compare bacterial and viral DNA and RNA with the
DNA from a eukaryotic cell . Students will also compare and contrast Gram
positive bacteria and Gram negative bacteria.
Students will use two different methods in microscopy (i.e. prepared slides
and wet mounts) to help them to identify various specimens of protists and
fungi. (NB They will only view pre -prepared slides of bacteria and
viruses) Students will be required to make biological drawings of all
their specimens at low power magnifications (x40 and x100) and high
power magnification (x400).
MB2.01
MB3.03
Students will use their understanding gained from their exercise on
microscopy of representative microorganisms to explain and illustrate the
differences in the gross structure between Bacteria and Viruses and how
scientists utilize their roles in various processes in genetic engineering
BOTTOM LINE
This lesson is designed to be an introduction to the field of microbiology (the study of microorganisms)
and a general investigation of the anatomical structures and design of representative microorganisms
or microbes from three different Kingdoms, Monera, Protista and Fungi. Viruses are not classified into
a Kingdom.
MATERIALS:
TEACHER
•
•
Reference textbooks with glossaries
Internet Access or charts downloaded from relevant
web-sites.
♦ CD ROM ON MICROORGANISMS Bacteria and
Viruses Cybered Inc., 1997)
♦ OVERHEAD PROJECTOR
♦ OVERHEADS (with TEM and SEM of various
microorganisms)
•
Materials for pond-water wet mounts :
Pond Water,
Welled microscope slides
Compound microscopes
Medicine droppers
•
Materials For wet mounts of bacteria:
Lima Beans in a dilute sucrose solution (sugar
and water) that has been placed in a warm
environment (28°° C) for 3-5 days.
Welled microscope slides
Compound microscopes
Medicine droppers
•
Prepared slides of representative microorganisms
from the Kingdom Monera (e.g. E. coli), Protista
(e.g. Amoeba or Paramecium, Diatoms, Euglena,
Trypanosoma, Plasmodium) and Fungi (gills of
Psalliota,) SEM's of common bacteria Micrococcus,
Salmonella and Spiroplasma (to show common
shapes)
PREPARED slides of Gram positive and Gram
negative bacteria
TEM's of Viruses (e.g. tobacco mosaic virus,
adenovirus, bacteriophage, Ebola virus).
Reference textbooks on the Kingdom Fungi
Button mushrooms
Toadstools (if they can be found and are in season)
Common bread mold (teacher grown)
Suspension of Baker's Yeast in a beaker
•
•
•
•
•
•
•
STUDENT
•
•
•
•
•
•
•
Required text
Pencil
Paper
Note book
Lab coat or old shirt
Checklist for student's drawings and labeling of
microorganisms.
STUDENT WORKSHEETS 1 and 2
TEACHER
•
•
•
•
STUDENT
Dust masks
Disposable latex or vinyl gloves
Checklist for student's drawings and labeling of
microorganisms.
Rating scale for student model of a
representative microbe that they have studied.
SAFETY CONCERNS
1. Review basic lab safety rules (taught from Grade 9) with students.
2. Caution students in avoiding spilling the culture liquid on themselves since they are dealing with a
living culture of bacteria.
3. Wash work area with an antibacterial soap mixture if spillage occurs.
4. Reinforce that precautions 2 and 3 are necessary, but that they, the students are in no danger since
the species of bacteria that are cultured (from the teacher instructions on growing bacteria) are
unlikely to be pathogenic and will not cause harm or disease to them.
5. If slides break during an experiment, dispose of them in the "sharps" container or bypass container
and clean up broken glass with the help of the teacher.
6. Make students aware of the location of the First Aid Safety Kit.
7. Have the students report ALL accidents to the teacher.
8. If handling poisonous fungi (e.g. toadstools) always ensure not to touch your oral cavity (mouth)
with your gloved hand as this can transfer spores into the mouth.
9. Fungal spores are airborne. It is imperative that if your students suffer from allergies that they not
be exposed to any of the fungi.
10. Even if they do not show symptoms of allergic reactions to these fungi, ensure that students wear a
protective dust mask when examining fungi.
LESSON SEQUENCE
1. Students will be introduced to microorganisms and the field of microbiology using an interactive approach. They
will be required to construct a glossary of terminology that will aid in their understanding and will be utilized in
further lessons (e.g. in writing their scientific paper).
2. They can view parts of the CD ROM multimedia show on microorganisms that will give them a general
introduction to the diversity, biology, use and environmental concerns about microorganisms. This is primarily to
engage the students on the topic and for them to appreciate how the world around them is teeming with invisible
life-forms, most of which are useful to humans .
3. Focus can then be placed on investigating the various shapes and structures especially on the genetic material (both
DNA and RNA) from bacteria and viruses.
4. Students will identify flagella, cilia, pseudopodium, plasmopseudopodium in bacteria, protists, and fungi. They
will also note the absence of these structures in viruses.
5. Students will then use VENN DIAGRAMS to compare the genetic material (DNA and RNA) of Prokaryotic cells
with that of Eukaryotic cells (e.g. Protist, fungi, plants and animals).
6. Using the information on microorganisms that the students elicit from the CD ROM show and supplemented with
overheads of the TEM's, SEM's and other biological drawings they will further illustrate the architecture of
representative microorganisms.
7. The teacher can assign relevant chapters in their textbooks to allow students to label and annotate their drawings
8. Students will also explore the classification system very briefly to understand the domains Archaea and Eubacteria
within the Kingdom Monera
9. MICROSCOPE ACTIVITIES using various cultures (some grown by teacher) or collected pond water, prepared
slides with representatives from the three Kingdoms (Monera, Protista and Fungi). In addition, TEM's of Viruses
and TEM's and SEM's of microorganisms can be set up on demonstration benches as references for students
10. Students will complete Worksheets 1 and 2 to help reinforce concepts learned .
MAKING WET MOUNTS AND OBSERVING LIVING MICROORGANISMS
Teachers will supply and collect pond water collected from creeks, sluggish rivers (if the waters are too fast flowing, it
is unlikely that you will collect any microorganisms) or can be harvested from an aquarium that has aquatic plants
growing in it and is lightly aerated. To make this exercise interesting, have a vial of boiled and cooled tap water (this is
a control, since the heating process should have killed microorganisms in the water) that the students will observe to
try to find living microorganisms.
HYPOTHESIS: Ask students to form a hypothesis on what they will find when observing a drop of freshwater
and a drop of pond water.
PROCEDURE
1. Retrieve two clean microscope slides and label them PW (pond-water) and TW (tap water).
2. Take the labeled slides to the station where the vials of pond water and boiled tap water are placed.
3. Using the medicine droppers that have been identified for use in each vial, place a small drop of pond water on the
slide labeled PW and replace the dropper in the pond water vial. Place a cover slip over the drop of pond water.
4. Take the dropper for the tap water and place a similar size drop of tap water on the slide labeled TW. Replace this
dropper in the tap water vial. Place a cover slip over the drop of tap water.
5. Using the low power lens (x100) of the microscope, search the field for any moving organisms. When you have
located a specimen, request the help of your teacher or instructor to help you identify it (bacteria, protist, or fungi).
6. Students will be required to make simple line drawings (using HP) of their specimens and will consult text books
to include labels.
7. After completing this exercise, discard the cover slips in the proper receptacle, and pla ce used slides in a bleach
bath.
PROCEDURE TO GROW BACTERIA IN A BEAKER (ADAPTED FROM FLEMMING, 1985)
NB INSTRUCTIONS FOR THE TEACHER TO PREPARE BEFORE THE LESSON
1. Make up a 10% sucrose solution and place lima beans or kidney peas in the solution in a jar or beaker.
2. Cover the beaker with saran wrap or foil, punching holes in the covers to allow air to circulate.
3. Leave the covered beaker in a warm environment (oven @ 28°C) or near a window that receives direct light for 35 days (NB There maybe an unpleas ant odour).
4. After day 3, pipette a sample near the surface using a medicine dropper, place in a microscope well or on a
standard slide, place a cover slip over the drop of water and observe under low and high power for organisms.
(This step is to determine the possible types of bacteria that may be growing in your cultures)
Students will then repeat the following steps.
1. Retrieve a clean microscope slide.
2. Take the slide to the station where the beaker of bacterial culture is placed
3. Using the medicine dropper that have been identified for use place a small drop of culture liquid on the slide and
replace the dropper in the beaker. Place a cover slip over the drop of culture liquid.
4. Using the low power lens (x100) of the microscope, search the field for any moving organisms. When you have
located a specimen, request the help of your teacher or instructor to help you identify it.
5. Students will be required to make simple line drawings (HP x400) of one of their specimens and will consult
textbooks to include basic labels.
6. After completing this exercise, discard the cover slips in the proper receptacle, and place used slides in a bleach
bath.
MICROSCOPE ACTIVITY (contd) FUNGAL MORPHOLOGY
1. Bring in some common mushrooms (e.g. white and portobello) purchased at the supermarket or farmer's market.
Have students study the various shapes especially the gills and caps.
2. Have students examine under the microscope the following: Make up a suspension of Baker's yeast (yeast, tepid
water @25°C). Have the students examine a drop of yeast under the microscope. (They should be able to see
budding in yeast cells real time)
3. Allow mold to grow on a piece of bread. Have your students take a small sample, mount this on a microscope
slide and examine the structure of common bread mold under a microscope.
4. The students will refer to the mycelia (thread-like structures that is the body of this fungus, black fruiting bodies
(sporangia) and spores (usually black or dark brown).
5. Students are required to make simple line drawings of all three types of fungi (mushroom, yeast and bread mold)
GRAM POSITIVE AND GRAM NEGATIVE BACTERIA
6. Students will be introduced to two different strains of bacteria based on the colour of the stain that is retained in
the peptidoglycan component of the cell wall of the bacteria
7. Revise the diagram of a generalized prokaryotic cell
8. Mention that there are 8 different cell parts or organelles
•
CAPSULE
•
CELL WALL
•
CELL MEMBRANE
•
GENETIC MATERIAL/ NUCLEAR REGION (DNA OR RNA)
•
CYTOPLASM
•
PILI
9. FLAGELLUM
10. RIBOSOMES
11. Students will discuss the difficulty in classifying bacteria based ONLY on their morphology or form
12. Danish physician Hans Gram (1844) devised a method to stain bacteria. Based on the staining in within the cell
wall of the bacterial cell, they are classified as follows:
•
GRAM +VE - thick cross-linked peptidoglycan and protein layer (e.g. BACILLUS)
•
GRAM -VE
coli)
- thinner cross-linked peptidoglycan protein layer and an additional outer thick membrane (e.g. E.
VENN DIAGRAMS
1. Have students construct two overlapping circles (see template at the end of this lesson)
2. Give the Venn Diagram a title (e.g. comparison of Eukaryotic and prokaryotic cells)
3. Label each of the circles accordingly.
4. Write the differences for each "subject" in the outer parts of the circles.
5. Write the similarities that the "subjects" share in the overlapping section of both circles.
6. Repeat the use of Venn Diagrams for comparisons of Bacterial and Viral DNA, Eukaryotic and Prokaryotic
DNA, Eukaryotic and Viral RNA etc.
TEACHING AND LEARNING STRATEGIES
•
CONSTRUCTED RESPONSE: Use of Think-pair-share or a JIGSAW approach to deconstruct relevant
terminology (microbiology, microorganism, DNA, RNA etc).
•
PRODUCT- SOCRATIC LESSON: Use of a CD ROM interactive program (CyberEd Inc.) or relevant
textbook chapters to introduce students to the biology of microorganisms.
•
PROCESS-FOCUSED- CONCEPT ATTAINMENT: Use of movie clip from an educational web site,
overheads of transmission electron micrographs (TEM) or scanning electron micrographs (SEM) of
representative microorganisms to introduce students to their anatomy, biochemical constitution, sizes and
diversity.
•
CONSTRUCTED RESPONSE: Students will construct VENN DIAGRAMS to compare the genetic
material (DNA and RNA) of prokaryotic cells especially Bacteria and Viruses with that of Eukaryotic
cells (e.g. protists, fungi, plants and animals).
•
PERFORMANCE: Use of microscopy methodology to study the architecture of different microbes
ASSESSMENT AND EVALUATION TOOLS
•
Peer assessment (using a rating scale) to determine accuracy and completeness of the definition of terminology.
•
Checklist to determine the completeness and accuracy of student's biological drawings of the different
microorganisms.
•
Rating Scale to grade the accuracy of student models of a representative microbe that they have chosen to study,
illustrate and provide annotated notes on.
•
Student Journal/ Portfolio to "file" exemplars e.g. Venn Diagrams.
•
Teacher-Student interaction: Grading in-class worksheets (1 and 2) done by peers or by teacher
ACCOMMODATIONS
•
•
•
•
•
balance of whole class, small group and individual instructions
balance of student-centered and teacher-directed activities
simplified tasks that focus on key concepts
experiential, concrete activities
ensuring the availability of written and verbal instructions during lab activities
EXTENSIONS (use one)
1. Student conference/discussion: Topic: How might life on earth be different if Bacteria were not
present?
2. Draw four cartoon characters that would best resemble a Bacteria, a protist a fungus and a virus
giving as much detail as possible that would help a student from the planet "Cartoonia" understand
structural and biological differences among these Kingdoms (Monera, Protista and Fungi) and
category (Virus).
BACKGROUND INFORMATION
Scientists and researchers who study microorganisms or microbes are called microbiologists. The field of
microbiology is a branch of biology that deals with the study of micro (very small) organisms (both plant and animal
bodies). Microbiology can be therefore be defined as the study of microbes which are all small organisms that require
the use of a microscope to see. There are many different species of microorganisms that have been classified or put
into similar groups based on the possession of certain characteristics. This is called taxonomy (the science of
classifying things) and the largest classification group is called the KINGDOM. There are five Kingdoms that
scientists use today to classify organisms, Monera, Protista, Fungi, Plantae and Animalia. Scientists classify organisms
into each of these Kingdom based on the similarity in structures (anatomy) or at the biochemical level based on their
genetic material.
All living organisms are composed of cells. There are two structural types of cells: prokaryotic cells are relatively
simple in structure; eukaryotic cells are more complex, in that they contain nuclei and different organelles such as
mitochondria, Golgi bodies and endoplasmic reticulum. Both types of cells have various structures on their outer
membrane, some of which are specialized for allowing the cell to be motile (ability to move).
All prokaryotic and eukaryotic cells contain genetic material. This genetic material can either be found in prokaryotic
cells as a single, circular or continuous strand without a nuclear membrane. In eukaryotic cells, genetic material is
found in the nucleus (a distinct nuclear membrane is present in ALL eukaryotic cells) in a condensed form called
chromatin. Genetic material is either one of two types, DNA or deoxyribonucleic acid or RNA or ribonucleic. Acid.
All living organisms contain DNA and RNA. However, viruses contain either DNA or RNA, not both.
Microorganisms use various types of motile structures (e.g. flagella, cilia, pseudopodia, plasmopseudopodia) that
enables them to move about to find food, search for optimal habitats, escape from predators or to seek mates.
Bacteria (singular-bacterium) are found in three basic shapes. They may be round, rod-shaped or spiral. A round
bacterium is called a coccus (plural - cocci). A rod-shaped bacterium is called a bacillus (plural-bacilli). A spiral
shaped bacterium is called a spirillum (plural - spirilla). Cocci and Bacilli are capable of forming chains and pairs.
Cocci can sometimes form clusters. Spirilla only live as single cells.
The Kingdom Protista contains many differently shaped organisms. All protists are considered to be 1) eukaryotic and
2) single celled or unicellular. While they are all eukaryotic, they aren't all unicellular. The algae in particular often
occur in many-celled or multi-cellular forms. Most of these are quite small such as plankton, but some get to be rather
large such as seaweed and kelp. Protists are aquatic and can live in both salt water and fresh water, in moist soil or are
parasitic within the bodies and cells of other organisms.
There are three large groups of protists. The three groups are the slime molds, the algae and the protozoans. Funguslike protists known as slime molds are fascinating organisms, often studied for their unusual life cycle and their mode
of nutrition (they obtain nutrients by absorption from the bodies and cells of their "prey").
Archaea and Eubacteria are fundamentally distinct. The Archaea are more "primitive" and include the group of
Prokaryotes that produce methane gas from simple carbon sources and usually live in extreme environments (e.g.
halophiles and thermophiles). The archaea bacteria usually have peptidoglycan absent from their cell walls. Eubacteria
(true bacteria) comprise a large and diverse order and are ones that have peptidoglycan in their cell walls (e.g. both
gram positive and gram negative bacteria)
GLOSSARY: Terminology and definition
Algae: A diverse array of photosynthetic organisms. Both planktonic and macroscopic forms exist in both freshwater
and saline habitats. Some exist terrestrially in soil or on the trunks of trees where they live symbiotically with fungi in
lichens (a symbiotic, biological association between a fungus and an algae).
Colonial: distinct individuals that live together and interact in mutually advantageous ways.
Fungi: Mainly many-celled organisms that have a nucleus. They have cell walls that are reinforced with a special
compound (a complex carbohydrate) called chitin. Many fungi produce thread-like bodies (e.g. bread mold) or they
may be large and fairly hard (e.g. mushrooms).
Microbiology:
the study of microorganisms or microbes; branch of biology that studies very small organisms (both
plants and animals).
Microorganism or Microbe: very small organisms that require the use of a microscope to see.
Monera: Usually single-cell organisms. Unlike members of the four other Kingdoms, members of the Kingdom
Monera do not have a nucleus. Examples of monerans are bacteria. Some bacteria are motile because of the possession
of one of more flagellum (plural flagella).
Multicellular: consists of many cells
Non-Pathogenic microorganism: a microorganism that usually does not case disease. They are usually helpful to
humans and their environment.
Pathogenic microorganism: a harmful microorganism that can cause disease.
Protista: Contains many different kinds of organisms. Most protists are single -celled, some are simple, many-celled
organisms. Some are animal-like (e.g. Amoeba and Paramecium), some are plant-like (e.g. algae or Euglena) while
others are "fungus-like" (e.g. slime molds). All members of the Protista have nuclei (singular nucleus). Amoeba can
use pseudopodia to move, Paramecium usually use cilia and slime molds can "creep" using pseudoplasmodium.
Protozoa: Subkingdom of Protista comprising unicellular and colonial microorganisms of varied morphology.
Reproduction commonly by asexual means binary fission (and multiple fission) and sometimes by conjugation (sexual
reproduction method).They are ubiquitous (found in both terrestrial and aquatic habitats) and some are pathogenic to
animals and humans (e.g. Plasmodium that causes malaria)
Saprotrophic: Obtaining nutrients from the dead and decaying bodies of other organisms
Slime molds: Multinucleate and saprotrophic in nutritional mode where a motile plasmodium "creeps" to find food.
They form fruiting bodies called sporangia where spores are formed by meiosis. These spores can survive poor
nutritional and growing conditions, and therefore aids in the survival of the slime mold.
Unicellular: consists of one cell only.
Viruses (NOT A TRUE KINGDOM) These are a group of minute infectious agents that are unable to reproduce and
multiply except inside the living cell of a host. Viruses are usually classified according to the type of nucleic acid
(DNA or RNA) that they may have. Some viruses such as the T4 Bacteriophage have special tail fibers that allow them
to become attached to the surface of the host cell.
HELPFUL HINTS
1. Since the students are conducting an experimental activity, revise basic lab rules that will apply to
their lab and that they are familiar with from their Grade 10 curriculum.
2. Reprint the set of experimental procedures that the students will need to execute the activity and if
possible distribute before the unit begins. If not, take the time to step them through the process.
3. Review the wet mount technique if deemed necessary.
4. When the students are finished with their experiments and have placed the slides in the bleach bath,
autoclave them before using then in any other experiments. If your school does not have an
autoclave then boiling the slides for 10 minutes should kill any remaining bacteria.
5. Identify the prepared slides that you will need for your lesson and view them before had if possible
so that you can identify the morphology of the microorganisms being studied.
6. Have a First Aid kit handy, if the students accidentally cut themselves.
7. As a just-in-case, purchase Paramecium and Amoeba from Carolina Biological supplies if the
teacher culture does not work
RESOURCES
TEXT BOOKS
Galbraith, D. (1989). Biology. Principles, Patterns and Processes. 634 p.
Solomon, E.P., L.R. Berg and D.W. Martin (1999). Biology. Harcourt Brace College Publishers. Fifth Edition,
1232 p.
ONLINE TEXT BOOK
URL SITE: http://cw.prenhall.com/bookbind/pubbooks/brock/
Madigan, Martinko and Parker (1999). Biology of Microorganisms. Eight Edition, Prentice Hall
Inc, Pearson Company.
WORKBOOK
Flemming, M.F. (1985). Life Sciences Labs Kit. The Center for Applied Research in Education Inc. 258 p.
Rosen, S. (1992). Biology, Survey of Living things, Science workshop series, Globe book company 242 p.
COMPUTER SOFTWARE
CD ROM: Bacteria and Viruses, CyberEd Inc, 1997.
FOR PEER REVIEW
RATING SCALE TO DETERMINE COMPLETENESS AND ACCURACY OF TERMINOLOGY
Student name: ______________________________________________________________
Date:_________________________________________
CATEGORIES
RANK
1. ALL key words were identified and written in 1
alphabetical order
2
3
4
2. ALL key words were defined
• The definition and meanings were interpreted and
written in the students own works
1
2
3
4
3. Diagrams were used appropriately to further aid in the
understanding of the term
• All lines were drawn with a ruler
• Applicable notes were printed and were legible
• No extraneous marks or pictures were present
1
2
3
4
4. Annotated references were included
• References were cited properly
1
2
3
4
5. Student initiative
• Other relevant terms were added
1
2
3
4
6.
1
2
3
4
Student's log is current and dated
TOTAL
/24
CHECKLIST TO DETERMINE THE ACCURACY AND COMPLETENESS OF BIOLOGICAL DRAWINGS
Student Name(s): ________________________________________
Date:_________________________________________
CATEGORIES
1. ALL drawings were attempted
2. All drawings were completed
• All relevant structures depicted
• High power and low lower structures were represented
on separate diagrams
• Annotated notes were relevant and helped to give further
details about the structure
3.
•
•
•
Drawings were neat
All lines were drawn with a ruler
Applicable notes were printed and were legible
No extraneous marks or pictures were present
4. Biologically accurate
• All structures were labeled
• Magnification of each drawing was included
NOTES (give hints regarding what was
missing)
RATING SCALE FOR COMPLETED MODELS ON THE ARCHITECTURE OF A NAMED MICROBE
Student name(s): __________________________________
Date: _________________________________________
CATEGORIES
RANK
1. Creation of the Model was attempted
1
2
3
4
2. Model completed
• All relevant structures depicted
• Each situation is depicted on a separate diagram
• TITLE was correct
1
2
3
4
3.
•
•
•
Model was neat and organized
All lines were drawn with a ruler
Applicable notes were printed and were legible
No extraneous marks or pictures were present
1
2
4.
•
•
•
Annotated references accurate
All structures were labeled
All stages were labeled
Key processes or events (annotated notes) were
described in detail
1
2
3
4
5. Model was accurate
• All relevant structures involved in reproduction were
depicted
• Process sequence was accurate (i.e. if the model requires 1
a series of diagrams to show the process, these must be
constructed in the correct order)
• Key LABELS were placed in the correct location
2
3
4
6.
2
3
4
Student's 3D model was original in design
TOTAL
1
3
4
/25
5
VENN DIAGRAM TO COMPARE A PROKARYOTIC CELL AND EUKARYOTIC CELL
PROKARYOTIC CELL
EUKARYOTIC CELL
Lesson #2: ECOLOGICAL SIGNIFICANCE OF MICROBES
EXPECTATION
CODES
EXPECTATIONS
MBV.01
Students will describe the characteristics of some microbes ESPECIALLY their role in the
environment (e.g. their ecology and growth patterns) and their synergism with and influences
on humans and other organisms (animals and plants)
MBV.03
Students will analyse and explain the role of microbes in within the framework of human
health practices, various biotechnology applications in Industry, research and medicine (e.g. in
the pharmaceutical industry and assess their use and acceptance in society and the
environment.
MB1.02
Students will review their knowledge from their preliminary exercise on microscopy of
representative microbes to help them to further understand the ECOLOGICAL significance of
the Kingdoms (Monera - Archea and Eubacteria, Protista and Fungi (and Viruses, which are
non-living). Students will elicit relationships between pathogenic microbes, their growth
patterns and how these relate to human diseases. They will also establish how "form is related
to function" (e.g. application of their knowledge on various motile structures in representative
pathogenic microbes and how this relates to ecological patterns such as the rapid increase in
population sizes of microbes and the potential for the spread of diseases.
MB1.05
Students will discover that microbes comprise more than 45% of the earth's living material and
understand that the numbers and living mass of prokaryotic cells exceed those of eukaryotic
cells almost four fold. Students will discuss and analyse various important symbiotic
relationships (e.g. Mammalian gut enterobes (Archaebacteria), mycorrhizal fungi that help
leguminous plants fix elemental nitrogen and commensal phototrophs (Protista: algae) that live
within the tissues of coral polyps. Students will also debate the importance of various niches
that microbes carry out and occupy.
MB2.04
Students will conduct a simple experiment on the rate of growth of a species of bacteria) at
different temperatures (X ºC). They will set up controls in order to determine the optimal
temperature for culturing a particular strain or species of bacteria.
MB3.01
Students will conference on and debate current topics such as antibiotic resistance of many
strains of pathogens, and make inferences on current medical dilemmas such as the emergence
of new and more resistant strains of bacteria, fungi and viruses and the threat that they pose to
the health and population dynamics of humans and other organisms
MB3.04
Students will evaluate the widespread use of pesticides and fungicides and how this practice
can lead to the demise of many species today. (revise the impact of DDT in the late 70's on
many species of birds and mammals that depended on plankton in aquatic food webs.
MB3.05
Students will also discuss the fundamental role that bacteria play as DECOMPOSERS in food
chains and how the recycling of nutrients is facilitated by many non-pathogenic species of
microbes (especially bacteria and fungi).
BOTTOM LINE
Most species of microbes are ecologically useful to Humans. For example, most Eubacteria and Fungi
are decomposers and are fundamental in the recycling of important nutrients and elements (e.g.
Nitrosomonas fixing elemental nitrogen, N2 ). Some microbes such as the planktonic algae are important
producers, some such as Protozoa are important in food webs, but some species are pathogenic.
Microbes play very important ecological roles in many terrestrial and aquatic habitats.
MATERIALS:
TEACHER
•
•
Reference textbooks with glossaries
Internet access or charts of various
microorganisms that have been downloaded
from relevant web-sites or posters of some
common microbes found in soil and in water .
STUDENT
•
•
•
•
•
•
♦ CD ROM ON MICROORGANISMS B acteria
and Viruses Cybered Inc., 1997)
♦ OVERHEAD PROJECTOR
•
♦ OVERHEADS (with TEM and SEM of
various microorganisms)
•
•
•
•
•
Agar plates
Inoculation loops
Bunsen burner
Wax pencil
Rubric for the Essay on the ecological
significance of microbes to humans and the
environment.
Required text
Pencil
Paper
Note book
Lab coat, old shirt or apron
Rubric for the Essay on the ecological
significance of microbes to humans and the
environment.
STUDENT WORKSHEET 3
SAFETY CONCERNS
1. Make sure that students can safely browse the Web Sites that they can use to help them with their
assignments.
2. Arrange with library personnel to ensure that only academic and credited Web Sites can be
accessed. This can be done via the various filters that have been set up within the browser (i.e.
Netscape or Microsoft Explorer.
ASEPTIC TECHNIQUE (adapted from University of Guelph's Laboratory Handbook)
The Aseptic technique is a fundamental but basic skill needed for any level of microbiological work.
There are basic components of the aseptic technique.
1. STERILIZATION: Most lab equipment and apparatus that is used in microbiological work are
autoclaved. This means that heat in the form of steam (>100°C) and at a high pressure is used to kill
resistant microorganisms and their spores. This will prevent contamination of your cultures.
2. WORKING CLOSE TO A FLAME: This aspect is very involved and will not be required at the
Grade 11 Level. There are additional safety concerns when working with open flames. The flame
usually generated from a Bunsen burner is on to sterilize (i.e. clean thoroughly) inoculation loops to
maintain pure bacterial cultures.
3 DISINFECTION: Before and after use, the bench top of the lab station is to be wiped with a
microbicidial solution consisting of iodine and detergent. This action will kill any vegetative (growing)
cells, but not spores, hence caution must be exercised in washing hands thoroughly after a
microbiological experiment.
LESSON SEQUENCE
1.
Students will be asked to recall from their first lesson and from their drawings the differences that were noted
about the different microorganisms that were observed.
2.
The teacher can then project overheads of typical or generalized microorganisms from three different
Kingdoms (Monera, Protista and Fungi) and allow student groups or individuals to state other similarities or
differences that they notice form the overheads and add these to those generated from their previous work.
They can write these in tabular form or in small groups, use information/word webs to condense their ideas.
3.
The students will view the CD ROM Bacteria and Viruses or appropriate ecological films (e.g. from the TVO
or National Geographic series). They will then brainstorm their ideas using a 4-MAT strategy and give an
overview (orally) on the ecological importance of a representative microbe that was featured from the CD
ROM or the film clips.
4.
Students will then use relevant chapters from their text -books, conduct research in the library using
Encyclopedias
and
other
references,
or
access
information
from
trusted
web
sites
with ecological
information. Students will construct an essay plan to be reviewed by the teacher from which they will write
their essay on "the ecological significance of microbes to humans and the environment". They will have two
days in which to complete this essay and submit it to be marked according to specifications given in a rubric.
5.
Students will be required to recall some of the physical and chemical factors that can affect the growth of
organisms in general and microorganisms in particular.
6.
They will analyse how these physico-chemical factors can affect the growth rates of individuals and
populations.
7.
Students will then conduct a simple experiment on the effect of a physical factor (temperature) on bacterial
growth. This activity will be done in small groups.
8.
Students will plate or streak a sample of bacteria (Serratia marchensis- which is coloured), on agar plates
using aseptic technique guidelines which will be explained and demonstrated by the teacher.
9.
They will culture their agar plates at five different temperatures (e.g. 0ºC, 5ºC, 15ºC, 25ºC and 40ºC).
10. Students will monitor their cultures over a three day period and examine all cultures for signs of bacterial
growth.
11. From their observations, they will make use the scientific method of inquiry to discuss their experiment.
12. Students can use class data to construct a graph on how temperature affects bacterial growth. They can also
find the optimal temperature to culture Serratia marchensis in the lab and discuss the shape of the graph in
terms of the four major phases (LAG, LOG OR EXPONENTIAL, STATIONARY OR PLATEAU AND
DEATH OR SCENESCENCE).
13. From the anecdotal information and that from their previous lab, they will then complete Student
Worksheet 2.
TEACHING AND LEARNING STRATEGIES
•
Use of a 4-MAT strategy to generate and review ideas on the classification of micro-organisms into their
Kingdoms.
•
BRAINSTORMING ideas or using Word webs on the significance of microbes to humans and their
environments (these can be used as guides to their essay plans.
•
Use of various educational sources (e.g. approved URL sites, textbooks, movie clips and CD ROMS) by
groups of students or on an individual basis to help them to build upon their ideas for their essay.
•
PROBLEM SOLVING: Generating class data on how temperature affects bacterial growth rates and
interpreting results from a graph.
ASSESSMENT AND EVALUATION TOOLS
•
PRODUCT : Rating Scale to assess the information presented in student essay.
•
PROCESS-FOCUSED: Use of the scientific methodology and student observations and class data to extrapolate optimal
temperature for growth of one species of bacteria in the lab.
•
CONSTRUCTED RESPONSES: STUDENT WORKSHEETS (3&4) to determine the level of understanding on the
importance of microbes (Monera, Protista, Fungi and Viruses) in human populations and their surroundings.
•
PEER-MENTORING: Students can check each other's essay plans as part of the review process. Teachers will ok the final
plan and mark the final copy.
ACCOMMODATIONS
1. balance of whole class, small group and individual instructions
2. balance of student-centered and teacher-directed activities
3. simplified tasks that focus on key concepts
4. highlighting major points
5. vocabulary drill
6. assistance with instructions/directions
7. notebook organization assistance
8. experiential, concrete activities
9. use of scribes (teacher or peer)
10. providing reading materials in advance
EXTENSIONS
Student conference or debate on finding practical examples where the large-scale use of pesticides and fungicides have lead to
resistance in some insects and plants, and how these chemicals may affect genetic diversity in microbes
BACKGROUND INFORMATION
Microorganisms or microbes are responsible for many reactions essential for the proper functioning of the biosphere.
In natural environments, the interaction of a microbe with the physical and chemical characteristics of the habitat, as
well as with other organisms, will determine its success in growing there (Madison et al., 1999). The recycling of
nutrients from organic compounds into inorganic forms that can be used by photosynthetic organisms is an especially
important function performed by microbial decomposers (Madison et al., 1999). Most microbes are useful to humans,
but some can cause disease (that is they are pathogens ) in humans, plants and animals. Care must be exercised when
handling microorganisms.
Bacteria are monerans. When most people think of bacteria, they think of disease-causing organisms, such as
Streptococcus bacteria that causes strep throat. Bacteria that cause disease are called pathogenic bacteria and are
notorious for such diseases as cholera, tuberculosis, syphilis and gonorrhea (which are two common sexually
transmitted diseases-STD's). However disease-causing species of bacteria are a comparatively tiny fraction of all the
different species of bacteria as a whole.
Bacteria are so widespread that it is possible only to make the most general statements about their life history and
ecology. They are found in many different habitats such as on the tops of mountains, the bottom of the deepest oceans,
in the guts of animals, in the frozen rocks and ice of Antarctica and on the rocks of hot springs. One feature that has
enabled them to spread so far, and last so long is their ability to go dormant for an extended period. Bacteria are also
very small and so large numbers exist in very small spaces.
Earth's ecosystem, both on land and in the water, depends heavily upon the activity of microbes. For example, bacteria
recycle nutrients such as carbon, nitrogen, and sulfur. Organic carbon, in the form of dead and rotting organisms,
would quickly deplete the carbon dioxide in the atmosphere if not for the activity of decomposers. This may not sound
too bad to you, but realize that without carbon dioxide, there would be no photosynthesis in plants, and no food. When
organisms die, the carbon contained in their tissues becomes unavailable for most other living things. Decomposition
is the breakdown of these organisms, and the release of nutrients back into the environment, and is one of the most
important roles of the bacteria.
The cycling of nitrogen is very important activity of bacteria. Plants rely on nitrogen from the soil for their health and
growth, and cannot acquire it from the gaseous nitrogen in the atmosphere. The primary way in which nitrogen
becomes available to them is through nitrogen fixation by bacteria e.g. Rhizobium. Some plants, such as legumes
(peas and beans) have taken special advantage of this process by modifying their structure to house the bacteria in their
own tissues called root nodules. The basic structures that bacteria are made up of are cytoplasm, a cell membrane and a
cell wall. All if not most species of bacteria need moisture and a proper temperature to grow and reproduce.
HARMFUL AND HARMLESS BACTERIA
Harmless and beneficial species of bacteria are found in much greater numbers than harmful species. Bacteria are used
extensively by humans in the agricultural industry. Since plants cannot use nitrogen gas, bacteria in the soil and in root
nodules change the nitrogen gas into a usable form called nitrates that plants can use to help them to manufacture
(make) their food through the process of photosynthesis. Bacteria are also used for preservation by pickling foods (e.g.
using certain species of bacteria in converting cabbage into sauerkraut). They are also used in fermentation (as in the
manufacture of yogurt, alcoholic beverages, vinegar, and certain cheeses), for decomposition of organic wastes (in
septic tanks, in some sewage disposal plants, and in agriculture for soil enrichment) and many other specialized
processes such as digesting oil. There are even bacteria that live inside the human digestive tract that help us produce
Vitamin K to aid in our digestive processes (Rosen, 1992).
Pathogenic bacteria include bacterial plant diseases are leaf spot and wilts; animal diseases caused by bacteria include
meningitis, food poisoning, tuberculosis, cholera, syphilis, typhoid fever and tetanus. Some bacteria attack the tissues
directly; others produce poisonous substances called toxins that can make one sick (e.g. Samonella bacteria that can
cause food poisoning.)
Bacteria tend to colonize (live in) every habitat on earth even in some very extreme environments where oxygen levels
are diminished or in low quantities. Yet some species of bacteria continue to thrive in these oxygen-deprived
environments. Due to the oxygen tolerance levels of different species of bacteria, scientists broadly categorize them as
follows:
GLOSSARY:
Strict anaerobes: grows only where oxygen is absent. Some species die rapidly when exposed to oxygen e.g. bacteria
that live in the intestinal tract of mammals would be categorized as strict aerobes.
Facultative anaerobes: grow best in oxygen but can grow in the absence of oxygen by stealing oxygen from foods
such as nitrate and sugars (e.g. E. coli the bacteria that causes food poisoning).
Strict aerobes: grows only where they get plenty of oxygen. Cannot tolerate low oxygen levels and will die soon if the
high levels of oxygen are not returned (e.g. Bacillus)
The Kingdom Protista contains many differently shaped organisms. All protists are considered to be 1) eukaryotic and
2) single celled or unicellular. While they are all eukaryotic, they aren't all unicellular. The algae in particular often
occur in many-celled or multi-cellular forms. Most of these are quite small such as plankton, but some get to be rather
large such as seaweed and kelp. Protists are aquatic and can live in both salt water and fresh water, in moist soil or are
parasitic within the bodies and cells of other organisms.
There are three large groups of protists. The three groups are the slime molds, the algae and the protozoans. Funguslike protists known as slime molds are fascinating organisms, often studied for their unusual life cycle and their mode
of nutrition (they obtain nutrients by absorption from the bodies and cells of their "prey"). Microscopic algae in the
plankton form the base of most aquatic food chains, assuming the role that green plants play on land Macroscopic
algae such as brown and red sea weeds have tremendous commercial value to humans. Protozoa (e.g. Amoeba and
Paramecia are also important players in plankton communities.
Members of the Kingdom Protista have various types of nutrition ranging from ingesting other cells (e.g. Paramecium
"eating" Amoeba), absorbing organic material (e.g. slime molds "eating"organic matter) and by photosynthesis (e.g.
algae both microscopic and macroscopic that contain chloroplastids and other phytopigments).
The kingdom Protista also contains many economically important pathogenic members, including protozoans that
cause disease such as trypanosomysis (African sleeping sickness) and malaria.
FUNGI
Fungi are fascinating microbes and are found in a variety of forms. They are mainly decomposers and are saprophytic
in nutritional mode. Their forms range from tiny microscopic cells such as yeast, the common bread mold (Rhizopus)
white mushrooms, giant brackets (ranging in lengths of more than 5 meters) on the trunks of trees to the deadly black
mold that can grow in damp crevices between walls in homes and schools. All fungi are eukaryotic and have a
complex carbohydrate chitin (similar to cellulose in plants) that helps to strengthen their cell walls.
This latter problem (i.e. moldy portables) has caused many individuals to become ill, because of the spores entering the
airways leading to the lungs. These spores can trigger an allergic reaction that can cause severe respiratory problems
and even death.
However all fungi are not harmful. Fungi both cure (e.g. Penicillin) and cause disease (athlete's foot). Fungi are
important in the recycling of nutrients in many food webs where they determine what plants grow in your yard and in
forests by decomposing plant and animal remains, and keeps the planet from being buried in waste.
Some fungi are grown for their commercial importance such as button mushrooms, Portobello mushrooms, morels or
truffles that are considered a delicacy in some parts of the world. Other fungi are highly poisonous e.g. toadstools.
These must never be ingested since the toxins that they produce can lead to death.
VIRUSES
Viruses are generally dangerous to humans, animals and plants, but because of knowledge gained through genetic
engineering, scientists have been able to use them in many ways. One practical use is in the horticulture industry where
botanists have used viruses to streak flowers such as tulips and African violets. Viral genes are currently being utilized
as vaccines to prevent crops such as tomatoes and tobacco from being destroyed.
HELPFUL HINTS
1. TEM's (transmission electron micrographs), SEM's, Drawings and diagrams of representative
microbes in their habitats .There are useful URL Web Sites to get these or make photocopies form
college textbooks.If theses cannot be obtained, then use appropriate movie clips (if they show
these microbes in their habitats).
2. Purchase Serratia marchensis ahead of time and plate them out on agar to have a back up set of
bacterial cultures, if the students are unable to complete their own.
RESOURCES
REFERENCE TEXTS
Addison Wesley Chapters 12 and 13
Audesirk, G and T. Audesirk (1993). Biology. Life on Earth. Third Edition 1049p.
Galbraith, D. (1989). Understanding Biology. John Wiley and Sons. 725 p.
Galbraith, D. (1989). Biology. Principles, Patterns and Processes. 634 p.
Solomon, E.P., L.R. Berg and D.W. Martin (1999). Biology. Harcourt Brace College Publishers. Fifth
Edition, 1232 p.
Morholt, Evelyn and Paul F. Brandwein, A Sourcebook for the Biological Sciences,San Diego:
Harcourt Brace Jovanovich, Publishers, 1986.
Nelson Chapters 9 and 10
Pendergrass, William R., Carolina Protozoa and Invertebrates Manual, Burlington: Carolina Biological
Supply Company, 1980.
Purves, W.K., G.H. Orians, H.C. Heller, D. Sadva (1998). Life. The science of Biology. W.H. Freeman
Company. Fifth Edition, 1243 p.
Name:
_____
Rating Scale For Essay
The letters used in assessing the Criteria for the Essay have the following meanings: E, Exemplary = 4+ , A=4; B=3; C=2; D=1; unacceptable
=0. Expectations are clearly set out in the description column.
Report Format
D
C
B
A
E
50+%
60+%
70+%
80+%
90+%
1
2
3
4
5
DESCRIPTIONS OF CRITERIA
CRITERIA
Report is properly organized and includes the
following sections in the proper order: Background
Information on microbes, classification of microbes
and the various types of microbes that are found in the
environment, current areas research in using microbes
in industry, medicine, biotechnology and genetic
engineering, General Discussion
REPORT SECTIONS
Background
Information was clear, concise and gives a general
overview on what is known about the ecology of
microbes.
1
2
3
4
5
Classification of
Microbes
Section contains an outline or overview of how
microbes are classified into kingdoms and a brief
section on prokaryotic and eukaryotic cells
1
2
3
4
5
Ecological
importance of
representative
microbes
A detailed treatment of information gleaned from
various sources (books URL's etc.) discussing how
representative microbes from each Kingdom and
category (Viruses) are either harmful or beneficial to
humans.
1
2
3
4
5
Applications of
microbial agents
in research
How researchers decode microbes at the genetic level
and use this information along with what currently
exists to find useful applications in various industries
(e.g. inserting the human gene for insulin production
into bacterial plasmids to make large quantities of
Insulin for medical use).
What are some of the concerns surrounding use of
microbial DNA and viral DNA to combat human
disease? How can manipulation of genes lead to the
loss of genetic diversity in organisms?
1
2
3
4
5
1
2
3
4
5
Report was neat, organized and well written using
proper grammar, punctuation and spelling.
1
2
3
4
5
General
Discussion
Overall assessment
TOTAL
/105
Lesson #3:PHYSIOLOGY AND BIOCHEMISTRY OF MICROBES
EXPECTATION
CODE
EXPECTATIONS
MBV.01
Students will describe some important physiological and biochemical characteristics of
microbes (e.g. factors that affect their growth patterns, physical requirements, chemical
requirements)
MBV.02
Students will conduct a simple experiment over a four-day period to investigate how physical
and chemical factors affect the growth rates of common bacteria sampled from their school
environment They will Recognize the value of knowledge in being prepared to conduct
an experiment with potentially dangerous organisms. Students will appreciate how
scientists project scientific thought in working cooperatively on a project to determine if one's
objectives have been met and if they can accept their hypothesis, given the results and the
method of experimentation. They will also understand why it is important to behave strictly in
a laboratory setting i.e. to ensure everyone's safety.
Students will analyse the role of microbes in Industry and technology, and assess their impact
on society and their environment.
MBV.03
MB1.02
Students will describe terminology dealing with 1. Microbial morphology, (e.g. reviewing the
differences among common bacterial shapes, bacilli, cocci and spirilli); 2. Microbial
experiments (i.e. growing bacteria) and aseptic techniques such as sterilization, disinfection,
inoculation loop, bunsen flame, agar medium, petri dishes, plating techniques.
MB1.03
Students will be briefly introduced to one common way that most microbes reproduce (i.e. by
binary fission which is an asexual method of reproduction.
MB1.04
Students will use the information from their study on the ecological importance of microbes to
humans and their environment to review and elicit physical and chemical requirements that are
fundamental to sustain growth. They will further understand how physical and chemical
factors such as temperature, pH and light can affect the growth of representative microbes.
MB2.02
Students will review basic Laboratory Safety rules and in particular revise and observe special
rules while investigating microbial growth (viz. bacterial growth) on agar in the Laboratory
using fundamental components of aseptic techniques.
Students should be able to vocalize, write and recall basic lab safety rules to their peers in
preparation for them conducting simple experiments on bacterial cultures.
MB2.03
Students will be introduced to the method of scientific inquiry in a Pre-Lab Talk. They will
observe a demonstration on simple aseptic practices and be able to repeat the procedures under
the guidance of the teacher or instructor. They will design and conduct an experiment using
the aseptic technique methodology to investigate how antibacterial agents affects the growth of
bacteria cultured from swabs taken from different sections in their lab or school. They should
be able to identify the various apparatus that they will be using in their experiments on
bacterial cultures.
MB2.04
Students will analyse their bacterial cultures in order to evaluate the effect of different
antibacterial agents on the growth rates of their bacterial colonies. They will also infer
how various factors such as temperature and pH affect the physiology of microbial
cells (in particular , bacterial cells)
MB3.04
Students will discuss how scientists grow successfully large numbers of genetically modified
microbes (in particular bacteria that produces human insulin ) in the laboratory by employing
their knowledge and research on the physiological and biochemical requirements of these
microbes
BOTTOM LINE
Students will be introduced to SPECIAL laboratory safety rules that are mandatory for executing a
microbiology exercise. They will become familiar with microbial aseptic laboratory techniques in order
to conduct an experiment on how physical and /or chemical factors can affect the growth of bacteria.
MATERIALS
TEACHER
•
•
STUDENT
•
•
•
♦ OVERHEAD PROJECTOR
•
♦ OVERHEADS (with diagrams) on special •
codes that apply in a microbiology lab (e.g. the •
biohazardous symbols).
•
•
Apparatus and Materials for sterilizing an •
inoculation loop to grow bacteria under aseptic
•
conditions (relatively speaking).
Reference textbooks on lab safety
Posters on WHMIS symbols and codes
¨ Inoculation loops
¨ Bunsen Burner
¨ Lighter
¨ Oven
¨ Vial with test solution (use water in this
demonstration)
¨ AGAR PLATES (Petri dishes wi th agar)
¨ microbial solution (iodine+detergent mixture)
¨ bottled water
¨ wax pencils or crayons
¨ discs soaked in four different types of
antibacterial solutions in four separate covered
petri dishes
¨ ANTIBACTERIAL
SOLUTIONS:
penicillin,
brand of antibacterial mouthwash, antibacterial
soap, sodium chloride solution
¨ Four needle-nosed forceps (one for each petri
dish with the discs soaked in the different brands
of antibacterial solutions
¨ Q-tips
¨ RATING
SCALE
FOR
GRADING
LAB
REPORT
•
Required text
Pencil
Paper
Note book
Lab coat or old shirt
Safety goggles
Hair restraint (rubber band or scrunch)
Hand-soap
Pre-Lab Summary sheet (notes)
Student Worksheet #4 (to be completed in a
few days after there is evidence of bacterial
growth),
RUBRIC ON HOW LAB REPORT WILL
BE GRADED
SAFETY CONCERNS
When one is working in a microbiological laboratory there are special rules that must be in strict
observance. Working in any laboratory setting stipulates a certain conduct of behaviour and where
behavioural practices can affect the out come of experiments and even one's own safety and the safety
of peers.
SPECIAL RULES FOR A MICROBIOLOGY LABORATORY
Ö Leave all coats, books and bags that are not directly involved with the lab at the back or side of the
room to avoid contamination.
Ö Students with long hair should tie this back to avoid contaminating the work area
Ö Lab coats are strongly recommended
Ö Always wash hands with soap and water before leaving the lab.
Ö Do not put pencils, pens etc in your mouth and avoid touching you eyes after handling samples
Ö DO NOT REMOVE CULTURES FROM THE LAB!!!! (Your instructor will show where used
lab apparatus may be placed.
Ö TREAT ALL CULTURES ARE POTENTIAL PATHOGENS!!!! If a spill occurs, flood the
area with the disinfectant provided and call the instructor.
Ö AT THE END OF YOUR PROCEDURE WIPE ALL SURFACES WITH THE
DISINFECTANT PROVIDED.
Before leaving the lab, ensure that all equipment is in the proper location and ensure that
water taps are turned off.
PRE-LAB TALK AND INTRODUCTION TO THE ASEPTIC METHOD (LESSON SEQUENCE)
1. Have students brainstorm what rules should be observed in a laboratory (this should be a review, since it should
have been covered in the Grade 9 or Grade 10 Science curricula.
2. Review general Lab Safety rules that will be observed during their lab on aseptic techniques.
3. Discuss the special rules that are mandatory when conducting and executing a microbiology laboratory.
4. Demonstrate the procedure outlined below on how to sterilize an inoculation loop and transfer a sample of
bacterial culture with this loop to an agar plate.
PROCEDURE
4.1 Light the Bunsen burner and adjust the flame.
4.2 Take the inoculation loop and place it in the blue portion of the flame.Heat the loop until it is red hot. When it
reaches this state, withdraw the red-hot loop from the flame.
4.3 Do not place the now sterilized inoculation loop on any other surface as this will cause it to become contaminated.
If the loop touches the bench, repeat steps 1&2
4.4 Uncap the vial and use the loop to collect a sample of the contents (i.e. skim the surface of the "culture"). This
sample is called the inoculum
4.5 Recap the vial and gently separate the petri dish lids.
4.6 Take the loop with the inoculum and gently streak the agar, taking care not to puncture the surface of the agar plate
(refer to Figures below).
AGAR MEDIA
Fig 1. Not a good streak as it is too thick
Fig 2. A GOOD THIN STREAK
PART A
1.
Students will follow review briefly the safety rules for a microbiology lab.
2.
Students will retrieve one agar plate (care being taken not to open them so as to expose the agar to the
environment and hence collect other air-borne bacterial spores).
3.
The agar plate will be "sectioned" into fifths with the wax pencil.
4.
Students will be asked to provide an oral rinse sample using the bottled water provided.
5.
They will collect this sample in a sample cup provided.
6.
Students will execute the sterilization process of the inoculation loop according to the protocol that was
demonstrated by the teacher (from the PRELAB talk).
7.
The sterilized inoculation loop will be used to transfer a sample of the oral rinse sample onto the five sections
of the agar plates.
8.
Gently separate the petri dish lids and use the loop with the inoculum to gently streak the agar in the five
sections, taking care not to puncture the surface of the agar plate.
9.
After the agar plate has been streaked, close the lid.
10. Open the lid gently and have an appointed student lab technician, the teacher or instructor place four discs
(from the supply) soaked in four different antibacterial solutions, one on each of four sections (that is, four
sections should have one disc soaked in a different antibacterial solution). As a control, place a disc soaked in
distilled water on the fifth section).
11. Use masking tape to secure the lids of the Petri dishes, invert and place in an area that is at one of the desired
temperatures (X°C) .
12. Repeat steps 7-11, four times and place each agar dish in the other locations at the desired temperatures.
13. Label the "prepared" Petri dish with your initials and the date.
14. Monitor (observe) bacterial growth on the agar plates over a 3-4 day period or according to the teacher's
instructions.
15. ANSWER THE QUESTIONS ON WORKSHEET 5 after there is bacterial growth.
NOTES:
After 24-48 hours growth of the oral bacteria may occur. An example of this growth is provided below. CAUTION: DO NOT
OPEN THE PETRI DISH WHEN THERE IS BACTERIAL GROWTH, AS THERE ARE BACTERIAL SPORES.
VIEW THE GROWTH THROUGH THE COVER.
Agar plate with different
bacterial colonies (represented
by different shapes)growing
on the surface of the agar.
AGAR
MEDIUM
LESSON SEQUENCE (Cont/d) PART B (Students can work in pairs or individually for this
activity)
TITLE: BACTERIAL GROWTH OF SWABS TAKEN FROM COMMON PLACES IN THE
LABORATORY.
HYPOTHESIS: Have students state this in the laboratory books
1. Ask the students to decide where in the lab they would like to take a sample. Decide upon three
locations.
2. Wet one end of the Q-tip in the water provided and swab one of the surfaces in the lab for about a
minute.
3. Gently open one of the agar plates and use this "dirty" end of the Q-tip to gently streak the sample
of bacteria onto the agar. (Exercise caution not to puncture the agar by pressing the Q-tip below the
surface.
4. Discard the used Q-tip in the receptacle provided.
5. Use masking tape to secure the lids of the Petri dish and write initials and location of the sample on
the lower lid.
6. Invert the agar plate and place in an oven set at 35°C or at another desired temperature.
7. Repeat steps 3-7 for the two of the other locations.
8. For the last agar plate, quickly open the lids, wait for 30 seconds and then replace the lids. Repeat
steps 5 and 6.
9. WASH HANDS THOROUGHLY AND CLEAN SURFACE AS DIRECTED.
10. STUDENTS WILL BE ASKED TO WRITE UP THE LAB PROCEDURE ON EITHER
THE LAB CONDUCTED IN PART A OR IN PART B (They will be evaluated using theLab
report rating scale).
NOTES: Bacterial growth can be rapid in 24 hours at 35°C. Again exercise caution NOT to open the Petri
dishes when viewing the colonies.
In the figure below is a diagram of the expected growth from just opening the Petri dish for a 30-second period.
NB. The big wh ite fuzzy
patches are fungal patches.
Fungal spores are
commonly found along
with bacterial spores in the
air
TEACHING AND LEARNING STRATEGIES
• Use of small groups or pairs of students to devise logical, practical and efficient strategies
in executing an experiment on bacterial growth.
•
Analyse the agar plates from Lesson #2 for signs of bacterial growth (especially those
cultured at temperatures greater than 20 ºC).. Students will conference to review how they
think temperature might affect the growth of bacteria.
•
PROBLEM SOLVING: Applying aspects of the aseptic technique such as streaking the
agar plate after sterilizing the inoculating loop to maximize the chances of growing single
isolated colonies.
•
Student work sheet (5) to be completed individually on the results of the Laboratory
procedures.
•
Formal Lab Report on the experimental procedures in the laboratory activities conducted
(i.e. state the following: Hypothesis, Materials and Methodology, Observations, Results,
Inference and Conclusion.)
•
Use of the pre-lab instructional summary sheet for students to use as a ready reference for
the aseptic technique (sterilization process etc.)
ASSESSMENT AND EVALUATION TOOLS
•
PRODUCT: Use of A RATING SCALE to check laboratory REPORT for accuracy and completeness.
•
PROCESS-FOCUSED: Use of observation from experiments on bacterial growth to deduce and evaluate how
physical and chemical factors can affect a physiological pattern
ACCOMMODATIONS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
balance of whole class, small group and individual instruction
balance of student-centered and teacher-directed activities
increased timelines for learning and the completion of activities
simplified tasks that focus on key concepts
modified handouts/workloads (outlining key points and sample calculations)
highlighting major points
paired reading
vocabulary drill
experie ntial, concrete activities
assistance with instructions/directions
accommodations or modifications as outlined in the Individual Education Plan (IEP) of exceptional
pupils
use of scribes (teacher or peer)
providing reading materials in advance
ensuring the availability of written and verbal instructions during lab activities
advising Special Education staff in advance when students are working on major course
assignments.
EXTENSIONS:
1.
Teachers can have students bring in several brands of yoghurt, take a small sample of the liquid portion,
mount it on a microscope, cover it and examine the smear for Lactobacillus bacteria. Have students draw the
shape of the cells on Poster paper.
2.
Students can be encouraged to bring in a kitchen sponge from home to take a swab of its surface and culture
this on an agar plate. They could also investigate bacterial growth on their agar plates from the sponge swabs
at different temperatures (e.g. @ 0 º C, room temperature (e.g. @ 25 º C and @ 37 º C (in an oven or in a
greenhouse if the school has one). (do this in groups).
3.
Students could also culture bacteria from a dirty thumb (unwashed) versus a clean thumb (washed with warm
water and antibacterial soap for two minutes, culture on an agar plate at the three different temperatures and
compare the results qualitatively. (do this in pairs)
BACKGROUND INFORMATION
The students will be using agar as their nutrient medium or culture medium to grow bacteria in the lab.
Agar is also called AGAR-AGAR, a gelatin-like product made primarily from red algae and brown algae (e.g. kelps);
Kingdom Protista). The best known use of agar is as a solidifying component of bacteriological culture media. It is
also used widely in canning meat, fish, and poultry; in cosmetics, medicines, and dentistry. Agar is isolated from the
algae as an amorphous and translucent product sold as powder, flakes, or bricks. Although agar is insoluble in cold
water, it absorbs as much as 20 times its own weight. It dissolves readily in boiling water; a dilute solution is still
liquid at 42º C (108º F) but solidifies at 37º C into a firm gel. In the natural state in the cells of algae, agar can occur as
a complex cell-wall constituent containing a complex carbohydrate (polysaccharide) with sulfate and calcium (Thane
and Hickman, 1980).
Bacterial growth usually follows a sigmoid pattern or "S" curve. There are four main phases, the lag phase (no
discernable growth) the log or exponential phase (steepest part of the curve where most growth occurs rapidly, the
plateau or stationary phase (#of cells produced = #of cells dying, hence there is no net growth and the death phase or
senescence where death of cells exceed the numbers growing and formed by binary fission as food supply is limited at
this point . Bacterial growth occurs rapidly at higher temperatures since enzymes work optimally at or around 3537ºC. Death can occur rapidly however it temperatures exceed this optimal range or if the pH changes.
HELPFUL HINTS
1. Bacterial colonies grow rapidly at warm temperatures. Carefully monitor the cultures that have been placed in
temperatures above 25ºC after 24 hours.
2. When viewing the bacterial cultures growing on the agar plates, place the petri dish on an overhead projector to
view the outline of the various colonies.
3. If the teacher is preparing the agar plates for this lab, then it has to be prepared and poured into sterlilized petri
dishes at lease one day before this lab is scheduled to begin.
4. Purchase ready-made agar plates as a just-in-case that the agar culture liquid does not set.
5. When you incubate nutrient agar plates in a warm place such as room temperature or a special incubator, the water
in the plate tends to evaporate and condense on the surface of the plate. If you incubate the plate right side up then
water drops form on the top of the plate and drip onto the plate causing bacterial colonies to be spread, the spread
very quickly in drops of water. But if you incubate the plate upside down the water is absorbed back into the plate
as it condenses so there is never more than a very thin film of water across the surface of the plate so the bacteria
can't spread more than they normally would.
6. The bacteria are very light, and do not easily "fall off" of the plate. They actually adhere to the plate and each
other, so they can grow even on a surface that is upside down, just like flies can land on the ceiling of your house.
STERILISATION / DECONTAMINATION WITH A PRESSURE COOKER
Autoclave Sterilisation:
1. Put about 5 cm of water into a pressure cooker.
2.
Place the items to be sterilised in the bottom of the pressure cooker taking care that no water will leak into media.
Caps on bottles MUST be loosened slightly. Attach the lid to the cooker and bring the water to boil so that you can
see the steam rising from the pressure vent. Attach the weight and start timing from the moment that the steam
pressure lifts the weight allowing steam to escape. This will ensure that the contents of the cooker will be sterilised
at the correct temperature and pressure for the correct amount of time. It is important that the seals are in good
order to allow the correct pressure to be reached.
3. Check for leaks of steam and replace the seal if necessary.
• For sensitive media: 10 lbs psi 10 minutes
• Normal sterilisation / decontamination: 15 lbs psi 15 minutes
4. Adjust the heat so that the pressure is just enough to lift the weight. Once the time is up, remove the cooker from
the heat source and allow the cooker to cool and the pressure to drop BEFORE attempting to remove the weight
and lid. Once the contents of the cooker have cooled, tighten all lids on media vessels OR discard decontaminated
material
RESOURCES
TEXTS
Biology I Laboratory Manual (Fall 1998). College of Biological Sciences. University of Guelph. Section 5.1-5.3
USEFUL TEXTS
Audesirk, G and T. Audesirk (1993). Biology. Life on Earth. Third Edition 1049p.
Galbraith, D. (1989). Understanding Biology. John Wiley and Sons. 725 p.
Galbraith, D. (1989). Biology. Principles, Patterns and Processes. 634 p.
Morgan, Kathleen S., ed., "Aseptic Technique for Cell Culture", Current Protocols in Cell Biology, John Wiley and
Sons, Inc., New York: 1998.
Perry, J.J., and Staley, J. Microbiology : Dynamics and Diversity, 2nd ed. Saunders College Publishing, 1997.
Purves, W.K., G.H. Orians, H.C. Heller, D. Sadva (1998). Life. The science of Biology. W.H. Freeman Company.
Fifth Edition, 1243 p.
Solomon, E.P., L.R. Berg and D.W. Martin (1999). Biology. Harcourt Brace College Publishers. Fifth Edition, 1232 p.
URL WEB SITES
Access Excellence Website (excellent resource for background material on handwashing and a place to get new
classroom activities --www.gene.com/ae).
Internet search of the topic "Aseptic Technique", (lots of information about how to do various procedures using an
aseptic technique).
DICTIONARY
Thain, M and M. Hickman (1980). The Penguin Dictionary of Biology. 10th Edition; Penguin Books, 678 p.
Name:
_____
Rating Scale For Scientific Lab Report
The letters used in assessing the Criteria for the Lab Report have the following meanings: 4+= Exemplary; 4= A; 3= B;
2; D= 1; Unacceptable: 0. Areas of weakness will be underlined or highlighted in the description column
CRITERIA
Lab Report Format
DESCRIPTIONS OF CRITERIA
C=
D
C
B
A
E
50+%
60+%
70+%
80+%
90+%
1
2
3
4
5
Purpose was clear, concise and explains
why the experiment was done.
1
2
3
4
5
Hypothesis was clearly stated and
addressed research question.
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
Lab report is properly organized and
includes the following sections in the
proper order: Introduction, Purpose,
Hypothesis, Materials & Methods,
Observations and Conclusions/Discussion
LAB REPORT
SECTIONS
Purpose
Hypothesis
Procedure/
Material &
Methods
Observations/
Results
Conclusion/
Discussion
questions
Overall assessment
Procedure was well planned, logical and
written in complete sentences in the passive
voice and past tense. Everything needed
for the experiment was listed in the
materials section. Controls were listed.
All appropriate qualitative and quantitative
information was collected. Data was
organized appropriately into tables and/or
graphs. All tables and/or graphs were
accurately drawn, labeled and had
descriptive titles
Valid conclusions were made based on
results. Statement was made indicating
whether hypothesis was correct. Discussion
questions were answered in full sentences
with much thought and effort
Lab report was neat, organized and well
written using proper grammar, punctuation
and spelling.
TOTAL
/105
Lesson #4: REPRODUCTIVE MECHANISMS AND LIFE CYCLES OF MICROBES
EXPECTATION
CODE
EXPECTATIONS
MBV.01
Students will understand the characteristics of sexual and asexual reproductive methods in
representative microbes and study unusual life cycles of representative microbes.
MBV.02
Students will analyse reproductive features of representative microbes by using their
microscopes to examine prepared slides, making and examining wet mounts where possible,
studying TEM's, SEM's, diagrams and drawings.
Students will recognize the value of understanding the mode of reproduction and the life
cycles of various microbes e.g. asexual reproduction allow bacterial populations to increase
exponentially over time. Therefore it is important for epidemiologists to act quickly when
there is a disease outbreak caused by pathogenic bacteria, in order to determine the extent of
the rate of spread of a bacterial infection if an outbreak were to occur. Students will also make
inferences on the selective (evolutionary) importance to microbes in being able to undergo
sexual reproduction
MBV.03
MB1.03
Students will define the following terminology:- to reproduce, sexual reproduction:
(transformation, transduction, conjugation) asexual reproduction: (binary fission, budding,
fragmentation). Students will also note that all microbes use the two main types of
reproductive mechanisms (asexual reproduction and sexual reproduction), but that asexual
mechanisms are more widespread.
MB1.04
Students will view prepared slides and SEM pictures of bacteria undergoing asexual or sexual
reproduction in order to examine the gross anatomy of reproductive structures in
representative microbes (e.g. the reproductive pili in bacteria, spore formation in fungi,
budding in yeast cells.
Students will identify, construct and label completely both the Lytic and lysogenic cycles of
viruses from prepared slides or SEM pictographs.
MB1.06
Students will analyse how ( microbial) cells retain their complement of genetic material (DNA
or RNA) from generation to generation through the process of replication of the genetic base
sequences before the cell divides.
Students will also apply basic Math skills to determine that binary fission occurs at a
remarkable speed. Given the relative size of a hypothetical bacterial population (after X
amount of time) starting with one cell and given the rate of division (# of cells in a given
amount of time, students should be able to envision the extreme numbers that bacterial
populations can grow to.
MB2.01
Students will analyse reproductive features of representative microbes by using their
microscopes to examine prepared slides, making and examining wet mounts where possible,
studying TEM's, SEM's, diagrams and drawings. Students will make anatomically correct
biological diagrams from their observation of various reproductive features in representative
microbes.
MB2.05
Students will work cooperatively to conduct a literature review on reproduction in two
representative microbes from two different Kingdoms. They will analyse their information
from various sources and create a plan to construct and complete a poster on this topic.
MB3.03
Students will discuss and evaluate how scientists use their knowledge of the reproductive
mechanisms of microorganisms especially in bacteria and viruses to introduce novel genetic
sequences form other organisms that will be expressed (e.g. bacteria making human insulin),
because of the rapid pace that bacterial cells multiply at, large quantities of insulin will be
produced.
Students will evaluate the differences in efficiency of drugs that are taken to treat viral
infections because during reproduction, viruses change their protein coats very often to cloak
themselves from being recognised by drugs developed to treat them.
BOTTOM LINE
Most microbes can reproduce both sexually and asexually. However, because there is no true exchange
of gametes (reproductive cells) between bacterial cells, sexual reproduction is often limited to the
exchange of genetic material (DNA or RNA). In general bacteria tend to use asexual methods to
reproduce.
Students will be introduced to interesting aspects of reproduction in selected protists. For example the
ability of Chlamydomonas to have both a sexual reproductive stage and an asexual reproductive stage is
termed "alternation of generation".
Viruses have a remarkable ability to reproduce even though they are non-living particles. They use two
cycles the LYTIC cycle and the LYSOGENIC cycle to make more copies of them selves. Your students
will learn about these two"reproductive" cycles in greater detail in this lesson
MATERIALS
TEACHER
•
•
Reference textbooks
Internet access or charts downloaded from
various web-sites (Refer to the specific URL
sites)
♦ CD ROM ON BACTERIAL
REPRODUCTION
♦ OVERHEAD PROJECTOR
♦ OVERHEADS (with diagrams) on microbial
reproduction mechanisms (e.g. binary fission,
budding and fragmentation).
• Drawings, diagrams or pictures of the sexual and
asexual reproductive stages in the life cycle of a
common protist (e.g. Chlamydomonas).
•
Materials for constructing poster:
¨ Bristol Board
¨ Construction paper Purchase a variety of colours
that students will use to represent the different
parts of the cell that are involved in the various
mechanisms of asexual and sexual reproduction
¨ Markers (permanent ink) and Ruler
¨ REFERENCE: Laminated Charts with diagrams
or drawings of
the different methods of reproduction.
¨ Rating scale to evaluate the completed poster
¨ Checklist for completed Life Cycle diagram of
Chlamydomonas
STUDENT
•
•
•
•
•
•
•
•
•
•
•
•
Required text
Pencil
Paper
Note book
Lab coat or old shirt
Bristol board
Silly putty or clay (to be used on their poster in
lieu of construction paper.
(optional) Construction paper (various colours)
students can use to represent the different parts
of the cell that are involved in the various
mechanisms of asexual and sexual reproduction
Markers (permanent ink) and Ruler
Rating scale to evaluate the completed poster
Checklist for completed Life Cycle diagram of
Chlamydomonas
STUDENT WORKSHEET 5
TEACHER
•
•
•
•
•
•
•
•
•
Button mushrooms
Toadstools (if they can be found and are in
season)
Common bread mold
Suspension of Baker's Yeast in a beaker
Microscope slides
Compound microscope
Medicine dropper
Vinyl gloves
Dust masks
•
OVERHEADS (with diagrams) on the LYTIC
and LYSOGENIC CYCLES of viruses
•
CD ROM (CYBERED INC. 1997) ON VIRUSES
AND BACTERIA - SECTION: BACTERIA
TVO VIDEOS ON VIRUSES - lytic and lysogenic
cycles or on their reproductive mechanisms
TELEVISION AND VCR
•
•
STUDENT
SAFETY CONCERNS
Caution students not to ingest or eat the silly putty or plasticine.
If a sharp object is required to cut the silly putty, make sure that it is used safely and returned to its
proper location after use.
Do not leave the overhead projector running when not in use. This will burn out the bulbs.
Review basic lab safety rules with students
When handling poisonous fungi (e.g. toadstools) always ensure not to touch your oral cavity (mouth)
with your gloved hand as this can transfer spores into the mouth.
Fungal spores are airborne. It is imperative that if your students suffer from allergies that they not be
exposed to any of the fungi.
Even if they do not show symptoms of allergic reactions to these fungi, ensure that students wear a
protective dust mask when examining the fungi.
There are indirect safety concerns in the section dealing with reproduction in viruses. Students will
NOT be handling " live" viruses, so there will be less concern about proper handling procedures.
However they will become aware of the TYPES of infective stages of viruses in both the lytic and
lysogenic cycles.
LESSON SEQUENCE
1. Students will read relevant section of their textbook, use glossaries provided (both online and from resource texts)
or from encyclopedias to help them to define the following terms: to reproduce, asexual reproduction, binary
fission, budding, fragmentation, sexual reproduction, transformation, transduction, conjugation.
2. Have students recall (in small groups) the following fundamental facts about bacterial reproduction.
•
Bacterial reproduction (both sexual and asexual) occurs in a number of stages.
•
Reproduction in bacteria may occur asexually by a form of cell division called fission or sexually by a transfer of
genetic material from a donor bacterium to a recipient bacterium.
•
Bacterial reproduction by asexual mechanisms is more prevalent than by sexual means.
____________________________________________________________________________________________
REPRODUCTION IN PROTISTS
1. Protists use both sexual and asexual methods to reproduce.
Demonstrate binary fission in a microscopic algae (Diatoms) Use two complete sets of petri dishes (one large and the
other smaller so that it fits into the larger one). Demonstrate how each new shell of the diatom retains half of the
original cell (using the petri dishes). Point out that as a result, one of the new shells is smaller than the other.
Students will then draw diagrams showing this form of asexual reproduction in dia toms (an algae)
Students will study the following Life Cycle diagram (Figure 1 below) and observe that the green algae
(Chlamydomonas) has both a sexual stage and an asexual stage and exhibits an alternation of generations in its life
cycle.
From Figure 1, the vegetative cells produced usually are haploid, and reproduce asexually by division into two, or
some small multiple of two, progeny cells.
Gametes look like vegetative cells, but have differentiated mating structures near their apices.
Cysts are usually diploid, form by fusion of gametes. Meiosis in the cysts usually yields four vegetative cells.
Students will define and understand that gametes (sex cells) are produced in protists that have a sexual life cycle, that
when they fuse a ZYGOTE is formed. (Revise relevant terminology on reproduction if necessary).
Students will reinforce their understanding of the alternation of generations in the Life cycle of
Chlamydomonas
and will draw and label a complete and accurate Life cycle diagram. They can check their work form the checklist
provided.
There is no embryo formed in the protist life cycle. Compare this with the human's life cycle where we are formed
from the fusion of gametes that grows into an embryo.
Students can then view prepared slides of protists such as Diatoms that undergo binary fission, which is a major
method of asexual reproduction. The main feature to note is that no gametes are produced during binary fission.
Students can then conference on disussing a really dangerous protist (e.g. Plasmodium that causes malaria in
many parts of the world and briefly look at its life cycle. (use a college level text book to get life cycle
diagrams for this.
Students will then complete STUDENT WORKSHEET 5
_________________________________________________________________________________________
FUNGI
Students will examine the life cycle of a common fungus the bread mold (Rhizopus) that produces non-motile spores
during its reproductive cycle. They can compare this to yeast cells that usually reproduce asexually by budding.
MICROSCOPE WORK:
Have students examine under the microscope the following: Make up a suspension of Baker's yeast (yeast, tepid water
@25°C). Have the students examine a drop of yeast under the microscope. (They should be able to see budding
in yeast cells real time)
Allow mold to grow on a piece of bread. Have your students take a small sample, mount this on a microscope slide
and examine the structure of common bread mold under a microscope.
The students will refer to the mycelia (thread-like structures that is the body of this fungus, black fruiting bodies
(sporangia) and spores (usually black or dark brown).
Students are required to make simple line drawings of all three types of the reproductive structures of representative
fungi (mushroom, yeast and bread mold)
Ask students to compare (conferencing or in small groups) the three main types reproductive structures of Fungi that
they have examined.
____________________________________________________________________________________________
VIRUSES
Students will briefly review the reproductive process in Viruses
They will review the concept of a non-cellular genetic element (VIRUSES) that contains nuclear material (DNA or
RNA) surrounded by a shell of protein, being able to reproduce. Because they have no metabolic machinery, these
viruses must infect cells and use the host's cellular "raw materials" such as their ribosomes, enzymes, and catabolic
potential to reproduce themselves.
Using the notes provided above or from other generalized Biology texts, the teacher can use a Socratic approach along
with slides to explain the different steps involved in the Lytic and Lysogenic cycles of viruses.
Students will be stepped through the various stages of the Lytic Cycle and will be required to draw this cycle in their
notebook.
Students will be stepped through the various stages of the Lysogenic Cycle and will be required to draw this cycle in
their notebook.
They will then construct a VENN DIAGRAM to compare and contrast the differences between both cycles
GUIDELINES FOR THE PRESENTATION OF POSTER
2.1 Review with your students what they have learned about cell reproduction, concentrating on asexual reproduction
in bacteria.
2.2 Using print materials and the Internet, students will also discover that sexual reproduction occurs by a transfer of
genetic material from a donor bacterium to a recipient.
2.3 Instruct students to use their notes and make diagrams as they do their research.
2.4 In class, encourage students to share their research findings.
[Award a small incentive (prize) for the best model (both in terms of accuracy and completeness)]
TEACHING AND LEARNING STRATEGIES
• INFORMATION REVIEW: Students will use a variety of educational sources to help them to
deconstruct relevant terminology that will be defined using the student's own understanding in
their notebook
•
Terminology can be PEER REVIEWED by a peer tutor or their teacher.
•
PRODUCT: Use of models (paper or plasticine / silly putty/molding clay) to construct simple
models of the lifecycle of a representative microbe (e.g. binary fission in Monerans) and compare
with another microbe from another kingdom (e.g. the alternation of generation in Chlamydomonas)
•
SOCRATIC LESSON to define and discuss the differences between the lytic and lysogenic
reproductive cycles in viruses.Use of a VENN DIAGRAM to elicit the differences between the
lytic and lysogenic cycles of viruses
•
Students will conference on the main differences between reproduction in viruses compared to
reproduction in a Moneran, Protista and Fungi by using their notes and other sources of infomation.
ASSESSMENT AND EVALUATION TOOLS
•
Use a Wraparound Strategy to check for student's understanding of terminology.
•
CHECKLIST for student to grade their own work on the Life Cycle Diagram of Chlamydomonas.
•
Use of A RATING SCALE to check student POSTERS for accuracy and completeness of annotated diagrams.
•
Checklist to determine the accuracy of the components of the VENN DIAGRAM eliciting differences between the
lytic and lysogenic cycles of viruses
ACCOMMODATIONS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
balance of whole class, small group and individual instructions
balance of student-centered and teacher-directed activities
increased timelines for learning and the completion of activities
simplified tasks that focus on key concepts
modified handouts/workloads (outlining key points and sample calculations)
highlighting major points
paired reading
vocabulary drill
notebook organization assistance
experiential, concrete activities
full or partial access to notes for tests, quizzes, exams
assistance with instructions/directions
accommodations or modifications as outlined in the Individual Education Plan (IEP) of exceptional
pupils
14. use of scribes (teacher or peer)
15. providing reading materials in advance
EXTENSIONS
1. Construct a model of a Bacterial cell showing the transfer of genetic material (DNA or RNA) form
a donor cell to a recipient cell (considered to be sexual reproduction).
2. Follow the package instructions containing the yeast to end its dormancy (i.e. provide the
conditions that would allow for optimal growth)
BACKGROUND INFORMATION
In bacteria the genetic material is organized in a single, continuous strand of DNA. This circle of DNA is localized in
an area called the nucle oid, but there is no membrane surrounding a defined nucleus as there is in the eukaryotic cells
of protists, fungi, plants, and animals. Bacteria do not have membranes that surround their genetic material nor the
organelles that they may posses. Hence bacteria are prokaryotic cells.
Bacteria are all around us. Given good growing conditions, a bacterium undergoes binary fission by growing slightly
in size or length, a new cell wall grows through the center forming two daughter cells, each with the same genetic
material as the parent cell. If the environment is optimal, the two daughter cells may divide into four in 20 minutes.
Asexual reproduction in bacteria occurs geometrically that is one bacterial cell divides into two, two into four, four
into eight and so on (1
2
4
8
16
32
64 etc. Given this rate of cell division using binary fission, why isn't
the earth covered with bacteria? The primary reason may be that conditions are rarely optimal to support bacterial
growth indefinitely. If bacterial growth was unchecked, the bacterial populations would exhaust their food supply and
space in their habitats.
PROTISTA
Summary: Chlamydomonas sp. is a eukaryotic unicellular, green alga (Kingdom: Protista). They can be found in
freshwater and moist soil environments. Chlamydomonas sp. are biflagellated (i.e. they have two flagella) and undergo
a haplontic life cycle (also known as the alternation of generation Life cycle) characteristic of many algal protists .
Chlamydomonas has been used extensively as a research system in cell biology and genetics.
NB: THIS SECTION CAN BE PHOTOCOPIED AND GIVEN TO STUDENTS
In general, most protists use both asexual and sexual methods of reproduction. Binary fission (also shown in the
Kingrom Monera) is the most common form of asexual reproduction found in most protists and is very common in
some protozoans such as Amoeba. Another form of asexual reproduction called fragmentation can also occur in some
protists. There are several forms of sexual reproduction in protists that involve the recombination of genetic material
from two individuals (e.g. conjugation in Paramecium) or from the fusion of gametes (e.g. in Chlamydomonas). The
development of sexual reproduction in protists allows for greater genetic diversity (mixing of the gene pool).
The green algae Chlamydomonas has a life cycle with an alternation of generations . This means that there are two
distinct cytological generations, one haploid and the other diploid. In their sexual reproduction cycle, haploid gametes
are produced (which are either a +gamete or a - gamete, as they are usually demarcated (See Figure 1 in this lesson).
The +gamete or a - gamete (from a different strain of Chlamydomonas), then fuse to form a zygote. Meiosis then
occurs forming four gametes (two +gametes and two - gametes). In the asexual cycle, the +gamete and - gametes,
both undergo mitosis to make more copies of themselves. Both generations are independent and are identical to each
other (as in Chlamydomonas).
We are aware that some protozoans are pathogenic. For example, a really dangerous disease called trypanosomiasis
(African sleeping sickness) and another called malaria are dangerous infectious diseases that can affect humans.
Trypanosomaisis is caused by a certain species of protozoan (Trypanosoma) and is spread by the blood-sucking tsetse
fly, Glossina. Because these protozoans can multiply rapidly using binary fission, they are able to infect healthy cells
of humans and animals in a short time. Knowledge about the reproductive cycle of these pathogenic protozoans can aid
researchers and medical personnel in treating the different stages of these microorganisms with particular drugs and
chemicals. For example, the asexual stage of Trypanosoma lives inside the blood stream and can eventually invade the
brain, causing mental deterioration, coma, and death. Malaria (a deadly disease still rampant in the tropics) is caused
by Plasmodium falciparum (a sporozoan protozoan) that is spread by the Anopheles mosquito. The asexual stage of
Plasmodium lives in the red blood cells which it eventually destroys leading to severe anemia.
____________________________________________________________________________________________
FUNGI
Many fungi are successful because they can produce enormous numbers of spores, both by mitosis or meiosis. Some
of the Characteristics of fungi are that they are eukaryotic, non- vascular organisms that reproduce by means of spores,
usually wind-disseminated, have both sexual (meiotic) and asexual (mitotic) spores may be produced, depending on
the species and conditions and like plants, fungi have an alternation of generations.
If you squeeze a ripe puffball fungus, a cloud of "dust" will puff out or if you place a mushroom cap over a white piece
of paper and leave this in the dark for a 24 hour period, an outline of spores will be printed onto the paper. If the cap is
ripe and you do this over a sheet of clean white paper you can see that it will be covered in tiny specks. These specks
are spores, the seeds of the fungus. Spores differ shapes and sizes and one mushroom can produce millions of them!
Most of spores are spread by the wind and can be transported over thousands of miles. The main body of the fungus is
simply a network of minute threads. The threads are called hyphae and the whole structure in called the mycelium.
The mushroom is the reproductive part and usually the only part we can see. It is built up of densely packed
hyphae. Most fungi after shedding their spores and wither away within a few days, but the mycelium stays, perhaps
living for decades. When the conditions are right it will repeat the process and produce more mushrooms.
___________________________________________________________________________________________
VIRUSES
Viruses are non-cellular genetic elements that contain nuclear material (DNA or RNA) that is surrounded by a shell
of protein. They are smaller than cells, ranging in size from 0.02 to 0.03 microns. Because they have no metabolic
machinery, these viruses must infect cells and use the host's cellular "raw materials" such as their ribosomes, enzymes,
and catabolic potential to reproduce themselves. Bacterial, animal, and plant cells are susceptible to infection by
specific viruses.
Viruses have two types of reproductive cycles -- (1) virulent or lytic cycle, in which new virus particles are
constructed and released (burst) from the host cell. The host cell is usually completely destroyed. (2)The virus
genome may become integrated into that of the host cell, and be replicated as part of the host as it grows. This process
is called the lysogenic cycle. Sometimes the host cell will survive this process.
In the lytic and lysogenic cycles, the virus must enter the cell. This involves two MAJOR steps.
1. Attachment to the surface of the cell. The type of cells a virus can infect is highly specific. A virus protein binds
specifically to a cell receptor, which generally has some non-viral cell function. This also accomplishes the second
stage of infection see the following online text book to help with your knowledge, visit the Web site
http://cw.prenhall.com/bookbind/pubbooks/brock/chapter8/deluxe.html.
2. Penetration. In some host cells, the cell wall and membrane are breached by enzymatic degradation and injection
of the genetic material into the cell. Note that the protein coat does not enter the cell. Its function is protection, and
the nucleic acid is capable of directing virus replication
3. An eclipse period follows where nucleic acid (DNA) is separated from the protein coat following infection. The
host (eukaryotic cell) can protect itself in a number of ways. One way is to have no receptor sites for the virus to
bind with (for example from the analogy of a piece or shape from a jigsaw puzzle, where only a specific shape can
fit into a specific slot of another piece). The second way, found in prokaryotes, is the production of special
enzymes called restriction enzymes, which attack the foreign nucleic acid.
4. In lytic infections there is latent period where nothing seems to be happening. However there are dangerous and
devastating processes that will follow. The subsequent important events are:
a) Replication of nucleic acid. - Take-over of host biosynthetic machinery to prevent synthesis of cellular proteins
and enable expression of viral genes (viral genetic material (usually DNA) is integrated here).
b) Assembly of genomes into protein coats to produce ineffective particles (dormant virus particles).
c) Release of copies of the virus from the cell.
NOTE: THESE FIVE PHASES IN THE LYTIC AND LYSOGENIC CYCLES OCCUR RAPIDLY AFTER
INFECTION OF A HEALTHY CELL. THE TIME-FRAME FOR THE PROCESS CAN BE 20-30 MIN IN
BACTERIA AND 8-40 HOURS IN ANIMAL CELLS.
GLOSSARY
/ ASEXUAL REPRODUCTION: reproduction involving spore production, but in which meiosis, gamete
production, fertilization, transfer of genetic material between individuals and parthenogenesis do not occur.
/ BINARY FISSION: vegetative reproduction occurring when a single cell divides into two equal parts.
/ BUDDING: asexual reproduction in which a new cell is formed as an outgrowth of a parent cell (e.g. in
yeast)
/ CONJUGATION: involves contact between two cells; two cells of different mating types
come together and genetic material is transferred from one to the other. (BEST STUDIED
MECHANISM IN E. coli.
/ FRAGMENTATION: asexual reproduction in which parts (usually unequal parts) of a cell give rise to new
cells.
/ REPRODUCTION: The production of new individuals, physically independe nt of their parents
/ SEXUAL REPRODUCTION: genetic recombination of DNA from two dissimilar cells (e.g. eggs and
sperm).
/ TRANSFORMATION: fragments of DNA released by a cell are taken in by another cell
/ TRANSDUCTION:
another
a phage (virus) carries bacterial genes from one bacterial cell into
HELPFUL HINTS
1. A wraparound strategy is one that entails an oral interactive dialogue between student and teacher.
Students will be given the opportunity to "teach" their peers about the topic by explaining the
concepts to the teacher. If there are limitations to the student's knowledge on concepts, the teacher
can appoint a team captain who will ensure that all members of their team will revise these
concepts and be able to explain then in writing or orally.
2. Another variation of the 4-MAT strategy, this involves giving a group of students (four) a single
sheet of paper, with four markers of different colours. Divide the paper into quarters (using two
+
bisecting lines
. They brainstorm the topic or concept being discussed, taking turns and write
their ideas their ideas in each quadrant of the. This method encourages students to work cooperatively toward a common goal and supports the student-centred approach.
3. Study the alternation of generation life cycle diagram to familiarize oneself with the dynamics of
both cycles.
4. Point out that many flowering plants share this type of life cycle where male and female gametes
are produced in special reproductive parts.
5. Photocopy the background information notes and step the students through, so that it can be used as
student notes as well.
6. Since the section on reproduction in viruses is a mainly Socratic lesson with drawings and notes, it
is important to make the lesson interesting to keep student's attention.
7. Make paper models of a T4 bacteriophage infecting a Bacterium (use an inflated cylindrical balloon
to represent the bacterium) and a hexagon with a middle column and two tails to make the T4). You
can use this to show the attachment phase in both cycles.
8. For the release phase in the LYTIC cycle, fill an inflated cylindrical balloon with assembled paper
T4's and then ask one of the students to burst the balloon while holding it up. This is a dramatic
step and bodes well even with difficult students.
9. To demonstrate the integration phase of the viral DNA into the host cells DNA in lysogenic cycle,
use two different colours of silly putty (one for the viral DNA, the other for the host DNA) to
model integration.
RESOURCES
TEXTS
Galbraith, D. (1989). Understanding Biology. John Wiley and Sons. 725 p.
Galbraith, D. (1989). Biology. Principles, Patterns and Processes. 634 p.
Solomon, E.P., L.R. Berg and D.W. Martin (1999). Biology. Harcourt Brace College Publishers. Fifth
Edition, 1232 p.
URL WEB SITES
http://tidepool.st.usm.edu/crswr/111prokaryotes.html#2 : an overview of a University level course with a
simple section on Reproduction in Bacteria.
http://cw.prenhall.com/bookbind/pubbooks/brock/chapter8/deluxe.html
(AN
http://www.britannica.com/seo/m/mosaic/ (use this site to help with terminology)
CD ROM ON VIRUSES - CyberEd Inc (1997).
ONLINE
TEXT
BOOK)
RATING SCALE FOR COMPLETED MODELS OR POSTERS ON BACTERIAL ASEXUAL REPRODUCTION
Student name(s): __________________________________
Date: _________________________________________
CATEGORIES
RANK
1. Creation of the Poster was attempted
1
2
3
4
2. Poster completed
• All relevant structures depicted
• Each situation is depicted on a separate diagram
1
2
3
4
3.
•
•
•
Poster was neat and organized
All lines were drawn with a ruler
Applicable notes were printed and were legible
No extraneous marks or pictures were present
1
2
3
4.
•
•
•
Annotated references accurate
All structures were labeled
All stages were labeled
Key processes or events (annotated notes) were
described in detail
1
2
3
5. Poster was accurate
• All relevant structures involved in reproduction were
depicted
• Process sequence was accurate
• Key LABELS were placed in the correct location
1
2
3
4
6.
1
2
3
4
Student's presentation of Poster was original in design
TOTAL
4
4
/25
5
FIGURE 1. LIFE CYCLE OF Chlamydomonas sp.
MEIOSIS
FERTILIZATION between
+gamete and a - gamete
MITOSIS
ZOOSPORE
CHECKLIST TO DETERMINE THE ACCURACY AND COMPLETENESS OF BIOLOGICAL DRAWINGS
Student Name(s): ________________________________________
Date:_________________________________________
CATEGORIES
1
•
•
•
ALL drawings to complete the Life Cycle diagram were
attempted
Gametes (+ and - were shown)
Zoospores shown
Zygote shown
2. All drawings were completed
• All relevant structures depicted
• The mitosis and meiosis stages were clearly represented
in separate parts of the life cycle diagram
3. Drawings were neat
• Applicable notes were printed and were legible
4. Biologically accurate
• All structures were labeled
• The alternation of generation reproductive methods was
clear from the student's drawing
NOTES (give hints regarding what was
missing)
VENN DIAGRAM TO COMPARE THE LYTIC AND LYSOGENIC CYCLE OF VIRUSES
LYTIC CYCLE
LYSOGENIC CYCLE
CHECKLIST TO DETERMINE THE ACCURACY AND COMPLETENESS OF INFORMATION
REPRESENTED IN THE VENN DIAGRAM COMPARING THE LYTIC AND LYSOGENIC CYCLES OF
VIRUSES
Student Name(s): ________________________________________
Date:_________________________________________
CATEGORIES
1. ALL DIFFERENCES for each cycle and all
SIMILARITIES shared by both cycles were attempted
2. DIFFERENCES and SIMILARITES listed in completion
• All relevant information depicted in proper parts of the
cells
3.
•
•
•
Drawings if included were neat
All lines were drawn with a ruler
Applicable notes were printed and were legible
No extraneous marks or pictures were present
4. Biologically accurate
• The various phases in each of the cycles were analysed
in sequence.
NOTES (give hints regarding what was
missing)
Lesson 5: PATHOGENIC (DISEASE-CAUSING) MICROBES - THEIR IMPACT ON HUMAN HEALTH
EXPECTATION
CODE
EXPECTATIONS
MBV.01
Students will describe the characteristics of a representative (named) microbe (e.g. their
ecology, growth patterns, reproductive mechanisms) in their scientific report
MBV.02
Students will make inferences on investigations of the growth and uses of microbes in the
laboratory
MBV.03
Students will analyse and explain the role of microbes in technology and assess their impact on
society, human health and the general environment.
Students should describe the basic characteristics of the microorganism that they have chosen
to report on.
MB1.01
MB1.02
Students should compare the life cycles of the microorganism that they have chosen to report
on
MB1.03
Students should be able to briefly explain the methods of reproduction used by the
microorganism that they have chosen to report on
MB1.04
Students will overview the anatomy and physiology of the microorganism that they have
chosen to report on.
MB1.05
Students should be able to report on vaccines that have been developed to treat the disease that
they have chosen to report on
MB1.06
Students will research a topic of choice on the transmission of a disease caused by a
pathogenic microorganism. They will analyse the topic and present an outline with the
suggested subheadings (Introduction, Brief History of the Disease, Biology of the Disease,
Preventative measures, References) before submission of the final Report.
MB2.01
Students should be able to identify the name (scientific or common) of the microorganism that
they have chosen to report on. Students should be able to recognise the Kingdom or category
to which the microorganism that they have chosen to report on, belongs
MB2.05
Students will be given time to conduct research using accredited educational web sites, library
searches, text books, scientific journals magazines and their notes to develop their ideas for
their final report.
Students will use a word processor or an editing program such as MS Word or Corel
WordPerfect to complete their final report.
MB3.01
Students will recognize the value of reporting knowledge to peers as a useful avenue of
educating groups about important and relevant issues. They will understand the process of
development an idea into a scientific paper or report. They will also appreciate why scientists
and researchers must ensure that their research findings are tailored to the specifications of the
scientific community to enable dialogue to ensue on common areas of interest.
MB3.02
Students will recognise some of the diseases that we are commonly vaccinated against in
infancy and childhood (e.g. Hib Vaccine, DTP -Diphtheria, Tetanus and Pertussis) and the
reasons why this is usually done in infancy.
MB3.03
Students will review the history of the development of vaccines and how standards of practices
have changed drastically today. They will also appreciate the difficulty that researchers and
scientists face in the development of vaccines against diseases such as Cancer, AIDS,
Influenza or the common cold because of the genetic makeup (RNA instead of DNA) of the
viruses that cause these diseases.
BOTTOM LINE
Students will write a scientific report aligned to specifications. Their report will be evaluated against a
rubric that will be given to them prior to this exercise, so that they can conduct their literature search
and review under the specific headings.
Students will also gain a general understanding on the history of vaccines and why humans have
developed them in medical research. They will learn more about common childhood diseases that are
now preventable with the development of vaccines against specific microorganisms.
MATERIALS
TEACHER
•
•
•
•
•
•
•
•
•
•
•
•
Reference textbooks with glossaries
Encyclopedia volumes on Microorganisms and the
diseases that they can cause
Biology dictionaries
COMPUTER S WITH INTERNET ACCESS
VIDEOS ON MICROORGANISMS
VCR
RELEVANT
CD
ROMS
ON
MICROORGANISMS
INFORMATION
CHARTS
FROM
HEALTH
CENTRES
ON
THE
NATURE
AND
TRANSMISSION OF COMMON MICROBIAL
DISEASES
Encyclopedia volumes on Vaccines
Biology dictionaries
TVO VIDEOS ON VACCINES TELEVISION
VCR
STUDENT
•
•
•
•
•
•
Required text
Pencil
Paper
Note book
Library pass/card (whichever is applicable)
Stude nt notes on MICROBES (to be used as
for background for planning sections of the
final report.
SAFETY CONCERNS
1. There are no actual safety rules that will be required for this lesson.
2. Students will be aware of relevant safety issues that they can include (if appropriate) in their essay.
3. If they are seeking information from community health centres, health personnel or botanical or
garden centres, they should not include actual examples of "diseased" (e.g. fungal rot) leaves or
fruits as part of their portfolio
4. There are indirect safety concerns in this lesson. Students will NOT be handling samples of
vaccines, so there will be less concern about proper handling procedures. However they will
become aware of the TYPES vaccines and how they are stored and introduced into the bodies of
humans and animals.
LESSON SEQUENCE
1. Students will be provided with background information that they can use to choose a topic of interest.
2.
The teacher can use the brief notes to present an overview to the students on several topics that they may
be willing to explore.
3. NB: Students will be given time (1 week) to draft an essay plan, and complete their report (hence
the students need to be made aware of this project by about the middle of the unit.
4. Ensure that their final report is computer generated to give then exposure to using various features of
word-processing.
5. They can complete the assignment in pairs or individually.
6. Students will define the term vaccination and relate this to the concept of immunity (use the example of
how a child develops an immunity to chicken pox (caused by a virus) when this is developed in infancy.
7. Discuss that humans can develop active immunity (immunity developed following exposure to antigens)
to viral diseases both naturally and artificially (through the use of vaccines).
8. Discuss that fact the active immunity lasts for many years, while passive immunity (e.g. at birth which
one gets from their mother) only lasts for a few months.
9. Use a team lead approach to help students to construct a simple ideas/concept map to aid in their
understanding of how vaccines are made and how they work.
10. Introduce the history of vaccines to allow students to gain insights into research that has been developed
through the science of microbiology that has eliminated microbial diseases as major causes of death in
developed countries.
11. Lead students into a MINI-debate a on a topic surrounding the inability of richer countries to effectively
apply public health controls in poorer developing countries that are ravaged by infectious diseases.
Many of these infectious diseases are caused by viruses and hence, although have been studied for many
decades are of importance since medical microbiologists and researchers are now turning to gene therapy
to help eradicate many of these viral diseases.
TEACHING AND LEARNING STRATEGIES
•
Use of Think-pair-share to discuss the initial ideas.
•
Presenting drafts of their ideas in an outline that develops their ideas in a logical and comprehensive manner.
•
PROBLEM SOLVING Using members of the health and educational research communities to help with
seeking knowledge on new findings and to foster a sense of community spirit on a matter that can affect us.
•
Use of small cooperative learning groups that will present arguments for and against the use of vaccines in
modern health practices.
•
PROBLEM SOLVING Use of small group ideas to help in the construction of the concept map on how
vaccines work.
•
SOCRATIC LESSON: Discuss the different types of vaccines available to humans and other current topics in
medical microbiology that relate to vaccine development technology. Students should be able to write a half
page report or write notes in point format on the importance of one of these vaccines.
ASSESSMENT AND EVALUATION TOOLS
•
Use a Wraparound Strategy to deduce the student's comfort level with the topic in order to provide advice and
information in developing their essay plan and final report.
•
Use a RUBRIC to grade assignment (see at the end). Specifications must be met (i.e. the various subheadings
should be expanded). This section should comprise most of the marks.
•
PEER ASSESSMENT: Use a student panel to judge student arguments.
•
RATING SCALE: To check ideas map on how vaccines work for logical sequencing.
ACCOMMODATIONS
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
balance of whole class, small group and individual instructions;
balance of student-centered and teacher-directed activities;
increased timelines for learning and the completion of activities;
simplified tasks that focus on key concepts;
highlighting major points;
paired reading;
vocabulary drill;
notebook organization assistance;
experiential, concrete activities;
full or partial access to notes for tests, quizzes, exams;
assistance with instructions/directions;
alternatives to writing assignments such as presentations, diagrams, etc.;
accommodations or modifications as outlined in the Individual Education Plan (IEP) of exceptional
pupils;
14. use of scribes (teacher or peer)
15. providing reading materials in advance
16. advising Special Education staff in advance when students are working on major course
assignments.
EXTENSIONS
You are an Intern at the Ministry of Health on Parliament Hill in Ottawa. Prepare a summary for a
Minister of Health to present to the United Nations Health Organization on the following topic:
"The use of vaccines to prevent diseases in young children caused by Microorganisms".
Your reason is that there have been cases where vaccines given to infants and young
children to prevent illnesses have resulted in just that - they contracted the disease
because the vaccine contains an attenuated (weakened) form of the virus that somehow
infected healthy cells of these children. Prepare arguments to either defend the use of
vaccines or to ban their use in young children
BACKGROUND NOTES (can be photocopied and given to students prior to this lesson for them to
prepare for their Scientific Paper)
EXAMPLES OF MICROBES THAT CAUSE DISEASE IN HUMANS
(1) Streptococcus pneumoniae, a cause of bacterial pneumonia. It infects the lungs, a strong inflammatory response
occurs which impairs lung function. The infection responds to the antibiotic penicillin; if untreated the infection
may be fatal.
(2) Diphtheria is caused by Corynebacterium diphtheriae. The organism infects the throat and tonsils. Its growth
forms a pseudomembrane which makes breathing difficult. Infection is prevented by immunization with DPT
vaccine. Infected individuals are treated with antibiotics and antitoxin.
(3) Infants are susceptible to Pertussis or whooping cough, caused by Bordetella pertussis. Bacteria adhere to cells
of the upper respiratory tract .A vaccine of killed cells is available.
(4) Mycobacterium tuberculosis is responsible for the lung disease tuberculosis. Primary infection occurs by
inhalation of droplets (e.g. from someone sneezing) containing the bacteria. The microbes grow in the lungs. The
body tries to fight off the infection. However, bacteria remain viable in tubercles for years. If the host is stressed,
these bacteria may be released and the lung infection will spread. Tuberculosis can be treated with the drug
isoniazid. Treatment must be continued for long periods to eliminate all pathogens embedded in tubercles.
(5) The common cold is caused by rhinoviruses. No effective long-term immunity can be generated because there are
more than 100 serologically different rhinoviruses. Because there are few antiviral drugs available, little can be
done to treat the infection.
(6) Influenza is caused by a family of viruses (e.g. Types A and B) transmitted from human-to-human through air.
Symptoms of fever, chills, fatigue and headache last 3 to 7 days, and then recovery is rapid. In individuals with
weakened defense mechanisms, (infants and the elderly), secondary infections such as bacterial pneumonia may
occur, and these infections may be fatal.
(7) Measles is caused by rubeola virus.
(8) Mumps, like measles, is caused by a paramyxovirus .
(9) Rubella is due to a togavirus . The virus is transmitted from mother to fetus during the first trimester of a
pregnancy, with severe effects. MMR vaccine , containing live attenuated viruses, provides protection against
these three diseases.
(10)
Varicella virus, of the Herpes group, causes chickenpox.
(11)
Sexually-transmitted diseases (STD) are caused by a cross section of bacteria, viruses, and protozoa. Public
health control is difficult because it requires information on sexual practices that are sensitive issues in society. All
these diseases are transmitted by intimate direct contact. Note that many of them can be transmitted to newborns
from infected mothers during birth. Examples of STD's are provided below:
-Gonorrhea The bacterium Neisseria gonorrhoeae infects mucous membranes, usually in the genitourinary tract.
Infections in females often go unnoticed. In males, the infection causes a painful inflammation of the urethra. In the
past, penicillin was effective in curing gonorrhea. There are now penicillin-resistant strains of gonorrhea.
-Syphilis is caused by the obligate anaerobe Treponema pallidum. There are three stages to the disease. After infection
through breaks in the epidermis, the primary lesion is a chancre at the site of entry, usually on the genitalia. This
disappears, but some microbes disseminate through the body to mucous membranes, joints, and the central nervous
system. The secondary stage is a skin rash In both stages, the individual is infectious. In the absence of penicillin
treatment, some individuals enter the tertiary stage, which can lead to cardiac failure
(12 ) HIV virus is the agent of the fatal disease AIDS. Fatalities result because the virus impairs the host's immune
system, so that the host is susceptible to opportunistic infections by microbes that are rarely invasive in healthy
humans. While no cure is available for HIV infections, several drugs are reported to delay the onset of AIDS.
Azidothymidine (AZT) is most commonly used drug and inhibits HIV replication. The genetic variability in the HIV
virus has slowed the development of an effective vaccine.
The History of Vaccination (adapted from http://www.who.int/vaccines-diseases/history/history.htm )
Introduction
There are two major public health interventions that have had the greatest impact on the world's health. These are clean
water and vaccines. The pioneering work of Edward Jenner and Louis Pasteur has resulted in the development of
vaccines that prevent illness or death for millions of individuals every year. But there is still a long way to go.
Immunization, the most cost-effective public health intervention, continues to be under utilized. It is profoundly tragic
that almost two million children still die each year from diseases for which vaccines are available at low cost. For
example, over 90, 000 humans are victims to paralytic polio, which could also have been prevented by immunization.
Indeed, many years have elapsed between the invention of current vaccines and their widespread use in immunization
programs. The reasons for these delays are many and complex. If history is to serve any useful purpose, it should help
us to find ways to avoid such delays in future.
There are a number of vaccines that have been developed through medical history that are now mandatory for every
newborn infant to receive in order to protect them from contracting potential viral illnesses. Remember that vaccines
can only supply a level of immunity before one contracts illnesses and disease from viruses.
Some of the vaccines that used in International and national immunization programs in Canada, the U.S. and
most of the Developing World are
Smallpox (now eradicated)
BCG - to fight tuberculosis
Diphtheria
Tetanus
Pertussis
OPV - oral polio vaccine
Measles
HELPFUL HINTS
1. There are many sources of information on various diseases that are caused by microbes. It is
advisable that you get information from a variety of sources before hand so as to determine what
level of information you require from your students in their report.
2. It is important that students not "zerox" information that is provided from various sources so as to
have a final product. Their writing must reflect that they have an understanding (e.g. of the how the
disease is spread, how the disease is treated, what drugs are currently being used to treat the
disease) of what they are writing about.
3. Students can begin preparing for this paper about one week into the microbiology unit. If they are
pre-empted into thinking about their topic, it will aid in the amount of preparation time to peruse
the information on their topic on the various diseases.
4. There are many college level and University level textbooks that have relevant information
pertaining to the topic on this lesson. However, because of the complexity of the terms and
concepts in how vaccines are developed, it is best to give general ideas on what vaccines are, in
order to prevent cognitive overload.
5. Read
the
material
posted
on
http://www.accessexcellence.org/AE/AEC/CC/vaccines_how_why.html
with how vaccines are made
the
URL
web
in order to familarize
site
oneself
RESOURCES
TEXT BOOKS
Galbraith, D. (1989). Biology. Principles, Patterns and Processes. 634 p.
Plotkin,S.A.and E.A. Mortimer (Eds) (1994). Vaccines. Philadelphia WB Saunders 245 p.
Solomon, E.P., L.R. Berg and D.W. Martin (1999). Biology. Harcourt Brace College Publishers. Fifth
Edition, 1232 p.
URL WEB SITE
http://www.accessexcellence.org/AE/AEC/CC/vaccines_how_why.html
IDEAS MAP THAT CAN BE USED TO DEVELOP THE CONCEPT MAP ON HOW TO MAKE A
VACCINE
PROBLEM: How can
we use a virulent
organism to make a
vaccine to protect us
from viral diseases?
Do we use the
live virus and
inject it into the
living organisms?
NO
Do we modify or change
the virus and then
introduce this changed
form into the body of the
living organism?
YES
Isolate the virus, change its
virulence but allow it to
retain chemical compounds
called antigens that are
important in inducing the
hosts immune response.
HOW DO WE DO THIS?
HOW DO VACCINES WORK?
Antigens from the disease causing
organisms trigger the immune
response. In response, the host
produces antibodies which bind to
receptor sites on the organism and
eventually leads to its destruction.
Memory cells are also produced and
thses help promote active immunity.
Kill the virus (or organism) with a
chemical called formalin. The vaccine is
now inactivated. The common Polio
vaccine is made this way today. Another
important way to make vaccines is to
weaken the live microorganism and then
introduce it into the living host This is
called attenuation and is more successful
than vaccines created using the inactivated
method.
CHECKLIST TO DETERMINE THE ACCURACY AND COMPLETENESS OF INFORMATION
REPRESENTED IN THE CONCEPT MAP SEQUENCING THE NEED FOR THE DEVELOPMENT OF
VACCINES
Student Name(s): ________________________________________
Date:_________________________________________
CATEGORIES
1. The problem was clearly stated, i.e. how to develop a
vaccine from a potentially dangerous microbe.
2. Sequencing of thought was clearly shown, i.e. each step
was a logical progression from the next.
•
The various steps from each cell were analysed in
sequence.
3. The concept map was accurate and neat
•
All lines were drawn with a ruler
•
Applicable notes were printed in each cell and were
legible
•
No extraneous marks or pictures were present
NOTES (give hints regarding what was
missing)
Name:
_____
Rating Scale For Scientific Report
The letters used in assessing the Criteria for the Lab Report have the following meanings: E, Exemplary = 4+ , A=4;
B=3; C=2; D=1; unacceptable =0. Expectations are clearly set out in the description column.
CRITERIA
Report Format
DESCRIPTIONS OF CRITERIA
Report is properly organized and includes
the following sections in the proper order:
Background Information, How the disease
is transmitted, how it is treated, future areas
of research to treat the disease, General
Discussion
REPORT SECTIONS
D
C
B
A
E
50+%
60+%
70+%
80+%
90+%
1
2
3
4
5
Background
Information was clear, concise and gives a
general overview on what is known about
this disease.
1
2
3
4
5
How the
Disease is
transmitted
Section outlines the name of the
microorganism , how it is spread (is it
airborne) and a brief explanation on the
biology of the disease causing organism
was clearly
What are the common drugs currently in
use to treat the disease Is it a vaccine , or
are scientists using another form of
research to help fight the disease
1
2
3
4
5
1
2
3
4
5
Future areas
of research to
fight the
disease
If applicable how will researchers use this
information along with what currently
exists to find more aggressive ways to fight
the disease.
1
2
3
4
5
General
Discussion
What are some of the concerns surrounding
this disease? Are patients supported by
public health systems in place to help them
cope with the disease? What is the general
outlook for patients with this disease?
1
2
3
4
5
Report was neat, organized and well written
using proper grammar, punctuation and
spelling.
1
2
3
4
5
How the
disease is
treated
Overall assessment
TOTAL
/105
WORKSHEET 1
(Answers are not provided for all questions because questions are based on a lab
activity)
ANALYSIS of pond water under the microscope
ANSWER ALL QUESTIONS.
1.Which organisms seem to be most abundant in the pond-water mounted on your slide ? Draw diagrams (in the space
provided) of these microorganisms. Label all visible structures on the microorganisms from your observation.
2.Of those organisms observed, would you consider them to be mainly Monerans or other types of microorganisms
from other Kingdoms? Justify your answer
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_____________________
3.Some Monerans may contain green and other coloured pigments in specialized organelles. Name the organelles
_______________________________. Do you think that some of these microorganisms can make their own food?
Provide an explanation.
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_____________________
4.Name two physical factors and two chemical factors that may affect the size of populations of microorganisms in a
pond.
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_____________________
5.If a population of microorganism is most abundant in a sample of pond-water because it hadno predators (organisms
that feed upon them) predict a possible outcome resulting from introducing a predator in the habitat occupied by this
microoarganism.
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_____________________
6.Draw a Venn diagram to compare and contrast a gram positive bacteria and a gram negative bacteria
ANSWERS TO WORKSHEET 1
(Answers are not provided for all questions because questions are based on a lab
activity)
ANALYSIS of pond water under the microscope
ANSWER ALL QUESTIONS.
1. Which organisms seem to be most abundant in the pond-water mounted on your slide ? Draw diagrams (in the
space provided) of these microorganisms. Label all visible structures on the microorganisms from your
observation.
2. Of those organisms observed, would you consider them to be mainly Monerans or other types of microorganisms
from other Kingdoms? Justify your answer
____________________________________________________________________________________________
____________________________________________________________________________________________
____________________________________________________________________________________________
______________________________
3. Some Monerans may contain green and other coloured pigments in specialized organelles. Name the organelles
CHLOROPLASTIDS. Do you think that some of these microorganisms can make their own food? Provide an
explanation. If there are chloroplastids present in some microbes, then it implies that they are
potentially capable of producing their own food through the process of photosynthesis. The
chloroplastids would contain chlorophyll (a green pigment) and other pigneth systems that the
organism could use to capture light energy to use in their photosystems to harness electrons
to drive the photosynthetic process.
4. Name two physical factors and two chemical factors that may affect the size of populations of microorganisms in a
pond.
ANSWER:
Physical factors: temperature,turbidity
Chemical factors: pH, toxins
5. If a popula tion of microorganisms are most abundant in a sample of pond-water because they had no predators
(organisms that feed upon them) predict a possible outcome resulting from introducing a predator in the habitat
occupied by these microorganisms.
ANSWER:
One of two scenarios could occur. 1. The predator will select prey based on nutritional status
and vailability. Population size will decrease initially because individuals are being preyed upon.
However, because the predator may have a choice of prey, then populations of prey may not be
decimated. 2. They predator population may increase in size because of the nutrients gained
from ingesting the prey, then they are able to reproduce more often. Hence populations of prey
may approach critical limits due to severe predation pressure.
6. Draw a Venn diagram to compare and contrast a gram positive bacteria and a gram negative bacteria
differences
Gram+ information:
Gram- information:
Similarities
thick layers of peptidoglycan (reinforced with amino acids)
thin peptidoglycan layer; thick OUTER membrane
Plasma membrane present
Transport proteins present
OVERLAP: both have peptidoglycan layers
WORKSHEET 2
ACTIVITY 1 Read the following and answer the questions below.
A time machine has transported you back in time and you have collected a prehistoric microbe. Back in the 30th Century, you have
discovered that this microbe that had very little structure, initially, found that it was beneficial not to have a nucleus and to exist
mainly as a single cell. However, upon examination of this microbe a week later, you noticed that it developed structures all over
its outer body and that it was now motile.
Questions:
1.
State the Kingdom in which you could classify this organism . _____________________________. Justify your choice
_____________________________________________________________________________________________________
_______________________________________________________________________________________________
2.
Why
do
you
think
that
the
microbe
developed
motile
structures
on
its
outer
body
wall.
_____________________________________________________________________________________________________
______________________________________________________________________________________________
2b.Namefour structures that microorganisms use to move about.
__________________________________________________________________________________________________
_________________________________________________________________________________________________________
_________________________________
ACTIVITY 2 Using your reference textbooks and other educational resources that describe the Kingdoms Protista and Fungi,
answer the following questions.
SCENARIO
You have been chosen to represent your High School in a Contest on Microorganisms. There is only one question to be answered
and the grand prize is a guest appearance on "Temptation Island", a popular reality TV show. The questions is "Based on
definitions and the different structures that microorganisms have, draw a simple classification key to show how the three
Kingdoms Monera, Protista and Fungi might have evolved from a common prehistoric ancestor. Your classification key should
indicate which Kingdom would have evolved first, next and so on.
COMMON
ANCESTOR
ACTIVITY 3
Study the Figures A-C below and answer the questions below.
Figure A
Figure B
Figure C
QUESTIONS
Look at Figures A, B and C. Use these letters to answer the following questions (1-4).
1. Which illustration shows Cocci________________________
Spirilla_______________________
Bacilli________________________
1b.Define each of the following terms in question 1a giving an example of a named microbe with these shapes.
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
__________________________________________________________________________
ANSWERS TO WORKSHEET 2
ACTIVITY 1 Read the following and answer the questions below.
A time machine has transported you back in time and you have collected a prehistoric microbe. Back in the 30th Century, you have
discovered that this microbe that had very little structure, initially, found that it was beneficial not to have a nucleus and to exist
mainly as a single cell. However, upon examination of this microbe a week later, you noticed that it developed structures all over
its outer body and that it was now motile, but its DNA is NOT contained in a nuclear membrane.
Questions:
1.
State the Kingdom in which you could classify this organism.
Monera . Justify your choice Cells are either
described as eukaryotic or prokaryotic based upon several characteristics. Some of
these characteristics are shared by both cell types e.g. the possession of a cell
membrane. However, ONLY in prokaryotic cells is the DNA not surrounded by a
nuclear membrane.
2.
Why do you think that the microbe developed motile structures on its outer body wall.
to help it to attach itself to surfaces
to move about for food,
2b. Name four structures that microorganisms can use to move about.
Flagella
Cilia
Pseudopodia
plasmopseudopodia
ACTIVITY 2 Using your reference textbooks and other educational resources that describe the Kingdoms Protista and Fungi,
answer the following questions.
SCENARIO
You have been chosen to represent your High School ni a Contest on Microorganisms. There is only one question to be answered
and the grand prize is a guest appearance on "Temptation Island", a popular reality TV show. The questions is "Based on
definitions and the different structures that microorganisms have, draw a simple classification key to show how the three
Kingdoms Fungi, Monera or Protista might have evolved from a common prehistoric ancestor. Your classification key should
indicate which Kingdom would have evolved first, next and so on.
COMMON
ANCESTOR
MONERA
PROTISTA
FUNGI
ACTIVITY 3
Study the Figures A-C below and answer the questions below.
Figure A
Figure B
Figure C
Figure C
QUESTIONS
Look at Figures A, B and C. Use these letters to answer the following questions (1-4).
3. Which illustration shows Cocci B
Spirilla C
Bacilli C
1b.Define each of the following terms in question 1a giving an example of a named microbe with these shapes.
1. COCCUS: A bacterial cell with a spherical shape. They are generally non-motile and
do not form spores They are diverse and can occur in the following forms:
- sphere or coccus
- diplococcus
- streptococcus (CHAIN)
- staphylococcus (CLUSTERS OR RANDOM)
- sarcina ( GROUPS OF EIGHT)
Example: Staphylococcus aureus (causes gastrointestinal diseases)
2. BACILLUS: rod-shaped bacterium. They usually occur in the following forms:
- rod or bacillus
- streptobacillus (chains)
Example: E. coli
3. SPIRILLIUM or SPIRAL: a long, rigid, helical bacterium.
Example: Spirillum minor
WORKSHEET 3
1. Justin plants two plots of crops in his backyard. Plot A is planted only with corn seeds. Plot B has mainly corn and
some soyabean (legume) plants growing among the furrows where the corn is planted. Justin adds the same
amount of fertilizer and gives the same amount of care to both plots. At the end of the growing season, Justin
harvests his corn for the local market and notices that Plot B has larger and better-developed corn. Give an
explanation why this occurred.
_______________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
___________________________________________________________________________________
2. How does a strict anaerobe differ from a facultative anaerobe?
_______________________________________________________________________________________________
_______________________________________________________________________________________________
______________________________________________________________________________________
3. Briefly discuss the advantages of bacteria being able to live where there are different levels of oxygen.
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
_______________________________________________________________________________________
_____________________________________________________________________________
4. The Kingdom Protista contains many representatives. The three main categories are listed below. Read the
questions and answer all questions.
PROTOZOANS
Three common protozoans are shown below in Figures 1, 2 and 3. Use these illustrations and your notes to
answer the following questions. Choose the more appropriate answer.
A. Protozoans are usually unicellular or multicellular organisms.____________________________
B. Figure 1 shows a protozoan that lives in the red blood cell of humans. Provide the term given to
dangerous protozoa _________________________________
C. Protozoans have a nucleus. To what Kingdom do they belong _______________________________
pseudopodium
flagellum
Figure 2. Diagram of Amoeba
Figure 1 Diagram of the flagellated stage of Trypanosoma
cilia
Figure 3. Diagram of Paramecium
ALGAE
Figure 4 Diagram of planktonic algae (diatoms)
Figure 5 Diagram of a macroscopic algae
5a. From Figures 4 and 5, list two habitats where these algae may be found
___________________________________________________
5b. State two reasons why algae are important to humans?
_______________________________________________________________________________________________
_________________________________________________________________________________________
6. LABEL ALL THE PARTS A-E ON FIGURE 6
A
B
C
D
E
Figure 4: Diagram of a mushroom: Kingdom Fungi.
ANSWERS TO WORKSHEET 3
1. Justin plants two plots of crops in his backyard. Plot A is planted only with corn seeds. Plot B has mainly corn and
some soyabean (legume) plants growing among the furrows where the corn is planted. Justin adds the same
amount of fertilizer and gives the same amount of care to both plots. At the end of the growing season, Justin
harvests his corn for the local market and notices that Plot B has larger and better-developed corn. Give an
explanation why this occurred.
ANSWER:
The cycling of nitrogen is very important activity of bacteria. Plants rely on nitrogen from the
soil for their health and growth, and cannot acquire it from the gaseous nitrogen in the
atmosphere. The primary way in which nitrogen becomes available to them is through nitrogen
fixation by bacteria e.g. Rhizobium. Some plants, such as legumes (peas and beans) have taken
special advantage of this process by modifying their structure to house the bacteria in their own
tissues called root nodules. The corn plants that grew in the plot with the legume benefited
from the nitrogen fixation because of the increased nitrates available in the soil.
2. How does a strict anaerobe differ from a facultative anaerobe?
ANSWER:
A Strict anaerobe grows only where oxygen is absent. Some species die rapidly when exposed to
oxygen e.g. bacteria that live in the intestinal tract of mammals would be categorized as strict
aerobes. A Facultative anaerobe grow best in oxygen but can grow in the absence of oxygen by
stealing oxygen from foods such as nitrate and sugars (e.g. E. coli the bacteria that causes
food poisoning).
3. Briefly discuss the advantages of bacteria being able to live where there are different levels of
oxygen.
ANSWER:
Bacteria tend to colonize (live in) every habitat on earth (e.g. in food, in the soil in the air)
even in some very extreme environments where oxygen levels are diminished or in low quantities
(e.g. inside the human digestive tract). Yet some species of bacteria continue to thrive in these
oxygen-deprived environments. The success of bacteria colonizing very diverse and extreme is in
part due to their levels of tolerance of oxygen and scientists broadly categorize according to
this ability. In addition to strict anaerobes and facultative anaerobes, there are also Strict
aerobes that grows only where they get plenty of oxygen. Cannot tolerate low oxygen levels and
will die soon if the high levels of oxygen are not returned (e.g. Bacillus).
4. The Kingdom Protista contains many representatives. The three main categories are listed below.
Read the questions and answer all questions.
PROTOZOANS
Three common protozoans are shown below in Figures 1, 2 and 3. Use these illustrations and your notes to
answer the following questions. Choose the more appropriate answer.
A. Protozoans are usually unicellular or multicellular organisms. Unicellular
B. Figure 1 shows a protozoan that lives in the red blood cell of humans. Provide the term given to
dangerous protozoa. - pathogenic
C. Protozoans have a nucleus. To what Kingdom do they belong - Protista
pseudopodium
flagellum
Figure 2. Diagram of Amoeba
Figure 1 Diagram of the flagellated stage of Trypanosoma
cilia
Figure 3. Diagram of Paramecium
ALGAE
Figure 4 Diagram of planktonic algae (diatoms)
Figure 5 Diagram of a macroscopic algae
5a. From Figures 4 and 5, list two habitats where these algae may be found
ANSWERS
Fig4. Diatoms: in saline habitats (e.g. open oceanic waters)
Fig5. Either freshwater of saline habitats usually rooted on the benthos
5b State two reasons why algae are important to humans?
ANSWERS
Microscopic algae in the plankton form the base of most aquatic food chains, assuming the role
that green plants play on land Macroscopic algae such as brown and red sea weeds have
tremendous commercial value to humans. Protozoa (e.g. Amoeba and Paramecia are also
important players in plankton communities.
Figure 6: Diagram of a mushroom: Kingdom Fungi.
A: CAP
B: GILLS
C: SPORES
D: STALK
E: RHIZOIDS
WORKSHEET 4
STUDENT WORKSHEET (to be completed in a few days after there is bacterial growth)
1. What is agar?
_______________________________________________________________________________________________
_________________________________________________________________________________________
2. Why do you think bacteria grew on agar?
_______________________________________________________________________________________________
_________________________________________________________________________________________
3. What did you do to lessen the chances of other bacterial spores growing on the agar apart from the spores that you
collected with the wet Q-tip swabs ?
_______________________________________________________________________________________________
_________________________________________________________________________________________
4. From your observations on the growth of the bacteria from the four different "locations", which one had the most
colonies? ___________________________________. Can you say why this location had the most bacteria?
_______________________________________________________________
5. The number of bacterial colonies are greater on agar plates cultured at higher temperatures (e.g. 37 ºC) than on
those cultured at 0 ºC . Briefly explain why this occurs.
_______________________________________________________________________________________________
_______________________________________________________________________________________________
______________________________________________________________________________________
6. Why were you cautioned NOT to open the Petri dish lids after bacteria had begun growing?
_______________________________________________________________________________________________
_________________________________________________________________________________________
7. List three Lab safety rules that you observed that helped you to conduct the lab safely?
_______________________________________________________________________________________________
_______________________________________________________________________________________________
______________________________________________________________________________________
ANSWERS TO WORKSHEET 4
STUDENT WORKSHEET (to be completed in a few days after there is bacterial growth)
1. What is agar?
ANSWER:
Agar is a nutrient medium or culture medium that is commonly used to culture bacteria in the
lab. Agar is also called AGAR-AGAR, a gelatin-like product made primarily from red algae and
brown algae (e.g. kelps); Kingdom Protista). Although agar is insoluble in cold water, it absorbs
as much as 20 times its own weight. It dissolves readily in boiling water; a dilute solution is still
liquid at 42º C (108º F) but solidifies at 37º C into a firm gel. In the natural state in the cells
of algae, agar can occur as a complex cell-wall constituent containing a complex carbohydrate
(polysaccharide) with sulfate and calcium.
2. Why do you think bacteria grew on agar?
ANSWER:
Most agar that is used to culture bacteria will usually contain additional nutrients that are
added to the media to maximize the chances of sustaining bacteria growth. Proteins from animal
sources are normally added to enrich the agar. Hence the bacterial cells were provided with
nutrients that sustained their growth on the agar.
3. What did you do to lessen the chances of other bacterial spores growing on the agar apart from the spores that you
collected with the wet Q-tip swabs ?
ANSWER:
The petri dish containing the agar (agar plates) were opened only slightly to minimize exposure
to airborne spoes.
4. From your observations on the growth of the bacteria from the four different "locations", which one had the most
colonies? ___________________________________. Can you say why this location had the most bacteria?
_______________________________________________________________
5. The number of bacterial colonies are greater on agar plates cultured at higher temperatures (e.g. 37 ºC) than on
those cultured at 0 ºC . Briefly explain why this occurs.
ANSWER:
Optimal growth occurs at temperatures that enzymes function optimally. In most living systems,
this temperature is at of near 37 ºC. Bacterial growth usually follows a sigmoid pattern or "S"
curve. There are four main phases, the lag phase (no discernable growth) the log or exponential
phase (steepest part of the curve where most growth occurs rapidly, the plateau or stationary
phase (#of cells produced = #of cells dying, hence there is no net growth and the death phase
or senescence where death of cells exceed the numbers growing and formed by binary fission as
food supply is limited at this point .
Bacterial growth occurs rapidly at higher temperatures
since enzymes work optimally at or around 35-37ºC. Death can occur rapidly however it
temperatures exceed this optimal range or if the pH changes.
6. Why were you cautioned NOT to open the Petri dish lids after bacteria had begun growing?
ANSWER:
Bacterial cultures on agar often contain fungal cultures that may produce spores in large
quantities. If there is fungal growth and the petri dish is opened, this maximizes the chances of
inhaling potentially harmful spores.
7. List three Lab safety rules that you observed that helped you to conduct the microbial lab safely?
_______________________________________________________________________________________________
_______________________________________________________________________________________________
______________________________________________________________________________________
WORKSHEET 5 (REPRODUCTION IN BACTERIA)
1. Describe the process of BINARY FISSION
_______________________________________________________________________________________________
_______________________________________________________________________________________________
______________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
______________________________________________________________________________________
2. Explain what is understood about the "alternation of generation" life cycle in Chlamydomonas
_______________________________________________________________________________________________
________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
______________________________________________________________________________________
_______________________________________________________________________________________________
________________________________________________________________________________________
_______________________________________________________________________________________________
_______________________________________________________________________________________________
______________________________________________________________________________________
3. Briefly describe two other forms of asexual reproduction used by microorganisms. Give examples of microbes that
utilize these mechanisms in each case
_______________________________________________________________________________________________
_______________________________________________________________________________________________
______________________________________________________________________________________
_______________________________________________________________________________________________
_________________________________________________________________________________________
4. Write three facts about bacterial DNA
_______________________________________________________________________________________________
_______________________________________________________________________________________________
______________________________________________________________________________________
ANSWERS TO WORKSHEET 5 (REPRODUCTION IN BACTERIA)
1. DEFINE the process of BINARY FISSION.
/ Answer: BINARY FISSION can be defined as vegetative or asexual reproduction occurring
when a single cell divides into two equal parts. It is as fast process e.g. from 1 bacteria à
we can get 1 billion in 10 hours {rate: doubles in less than 20 min}
2. Explain what is understood about the "alternation of generation" life cycle in Chlamydomonas
Answer: The green algae Chlamydomonas has a life cycle with an alternation of generations.
This means that there are two distinct cytological generations, one haploid and the other
diploid. In their sexual reproduction cycle, haploid gametes are produced (which are either a
+gamete or a - gamete, as they are usually demarcated (See Figure 1 in this lesson). The
+gamete or a - gamete (from a different strain of Chlamydomonas), then fuse to form a
zygote. Meiosis then occurs forming four gametes (two +gametes and two - gametes). In the
asexual cycle, the +gamete and - gametes, both undergo mitosis to make more copies of
themselves. Both generations are independent and are identical to each other (as in
Chlamydomonas).
3. Briefly describe two other forms of asexual re production used by microorganisms. Give examples of
microbes that utilize these mechanisms in each case.
Answer:
/ BUDDING: cell develops a large bud or bulge that matures and separates from the mother
cell e.g. in Saccaromyces - yeast cells (Kingdom: Fungi)
/ FRAGMENTATION: WALLS DEVELOP WITHIN THE CELL GIVING RISE TO NEW CELLS
(e.g. in Volvox (Kingdom: Protista.
4. Write three facts about bacterial DNA
Answer:
/ Bacteria have a single circular DNA molecule (1000 times longer than the cell itself)
/ Bacterial DNA have little protein associated with it
/ In addition to genomic DNA, bacteria have PLASMIDS – small circular fragments of DNA.
Plasmids can replicate independently of the genomic DNA.