Download Laboratory # 2 Observation of Microorganisms Purpose: The

Laboratory # 2 Observation of Microorganisms
Purpose:
The purpose of this laboratory exercise is to familiarize the student with the wide
range microorganisms.
Introduction:
Definition of a Microorganism - a microscopic form of life that can only be studied
under a microscope, including bacteria, viruses, fungi, algae, protozoa and some
multicellular parasites.
Divisions of Microorganisms - they can be divided into Eukaryotes and
Prokaryotes dependent on whether they have cellular membranes enclosing specific
organelles within their cells
Eukaryotes - a relatively complex organism, whose cells contain organelles
as well as a nucleus with multiple chromosomes and a nuclear membrane,
reproduction of the organism is by mitosis.
Groups to be studied include:

Protozoans:
Single celled animal-like microorganisms
Found within aquatic environments
Many are capable of motility (independent
movement)
Food is obtained by engulfment.
Some protozoans are pathogenic (disease
producers)
Others are not, but these are considered good
aquatic indicators and members of the next to
lowest rung of the food chain

Algae:
Can be single celled to multi-celled
microorganisms
Capable of photosynthesis, therefore are
called producers
Also good aquatic indicators and members of
the lowest rung of the food chain
1
Prokaryotes - a relatively simple microorganism composed of single cells
and having a single chromosome, with no nucleus, or nuclear
membrane, and few intracellular organelles, reproduction
does not involve mitosis.
Groups to be studied include:

Cyanobacteria:
Formerly called blue green algae,
But possess a prokaryotic cell structure.
Possess chlorophyll
Arranged as single cells, within a gelatinous
matrix or filamentous colonies.
Heterocyst, if present stores nitrogen from
the atmosphere.
Found in fresh water, damp soils and
anaerobic environments.

Eubacteria:
Also known as true bacteria
Have cell wall of peptidoglycan and lipids
Vast majority of bacteria fall in this group
Objectives: The student after completion of this exercise will be able to:
1.
2.
3.
4.
5.
Identify pictures of the microorganisms listed below (in materials section).
Identify the important components of each of the microorganisms listed below.
Explain the importance of each of the microorganisms listed below.
Describe the category to which each microorganism belongs.
Describe the possible shapes and arrangements of bacteria.
Materials:
Live cultures of:
Prepared slides of:
Amoeba proteus
Paramecium
Euglena
Spirogyra
Anabaena
Gloeocapsa
Amoeba proteus
Euglena
Spirogyra
Anabaena
Gloeocapsa
Giardia lamblia
Trypanosoma brucei gambiense
Diatoms
Typical Bacterial shapes
2
Procedure:
1. Student will observe the live microorganisms using a wet mount and make the
required sketches.
2. Student will also observe prepared slides of some microorganisms and make the
required sketches.
Observation of Eukaryotes: Protozoans
1. Amoeba proteus
a. Live prep/Wet mount: Place a drop of the sample on a slide and then place
coverslip over it. Observe the slide first under 4X and then under 10X. Compare
the specimen with the diagram in your laboratory atlas.
b. Observe the prepared slide and compare it to what was observed on the wet
mount. Make a sketch of your observations below.
c. What is the method of locomotion for Amoeba proteus?
_______________________________________________________
2. Giardia lamblia - first observed by Leeuwenhook in 1681. Giardia infects the small
intestine of humans. The parasite has adhesive disks that attach to the bowel wall. Observe
the demonstration slide use 100X and compare it to the diagram below. Also make your
own sketch of this microorganism.
a. How would one contract this microorganism?
________________________________________________
3
b. What symptoms does the microorganism produce in humans?
_________________________________________________
c. Why must back packers both chlorinate & filter their water?
_________________________________________________________
3. Trypanosoma brucei gambiense – this is a pathogenic protozoan that causes the disease
called "African Sleeping Sickness". Observe using 100X. Make a sketch of the prepared
slide and label the following:
a. Human Red Blood Cells
b. Human White Blood Cells
c. Trypanosoma gambiense parasites
What is the vector for African Sleeping Sickness? _____________________
What is a late symptom of this disease? _______________________________
4. Paramecium – a slipper shaped microorganism is motile by the presence of rows of cilia,
this allows for smooth and rapid movement through water.
Observe the wet mount preparation and the prepared slide of Paramecium on 4X and
make a sketch of it in the space provided below.
.
4
How does this microorganism take in its food? ____________________
Why is this microorganism important? _____________________________
Observation of Eukaryotes: Algae
1. Spirogyra:
Observe this alga as a wet prep and then as a prepared slide. Make a sketch of your
observations in the space provided.
What are the spiral shaped organelles within the Spirogyra called? ___________________
2. Diatoms: yellow brown algae
Observe the prepared slide of diatoms and make a sketch of what you observe in the
spaced provided below.
What is the light trapping pigment within Diatoms called?
__________________________
5
After this microorganism dies it still has two important uses, name them.
_______________________ ___________________
Observations of Eukaryotes: Euglenoids
1. Euglena –
Make a wet prep of Euglena and observe this microorganism’s rapid movement.
Also observe the prepared slide of Euglena.
Make a sketch below of your observations.
List the two characteristics which indicate that this microorganism could be classified as
either a protozoan or algae.
Observation of Prokaryotes: Cyanobacterium
1. Anabaena - a symbiotic bacterium often found in association with Azolla a water fern.
The bacterium is found within the pores of the fern. Sketch this Cyanobacterium as it
appears under 10X and label the area called the heterocyst. (Live & prepared slide)
6
How can you differentiate the heterocyst from the other cells of Anabaena?
_______________________________________
What is the function of the heterocyst? __________________________
7
2. Gloeocapsa - found on wet rocks and other damp areas where it forms masses of jelly. The jelly
contains masses of single cells.
Observe a wet mount of Gloeocapsa on 10X and also the prepared slide on 40X. Make a sketch
of your observations below.
What is the function of the capsule? (Hint: The answer is not so it can attach to rocks!)
_________________________________________
Why is Gloeocapsa important? ____________________________
Observations of Prokaryotes: Eubacteria
In this section you will be observing shapes of Eubacteria only, therefore no bacterial
names will be given.
1. Typical coccus - cells appear as spherical, in clusters that often are referred to as grapes.
Sketch what you observe under 100X magnification.
2. Typical bacillus - cells appear long and narrow, they may contain stacked or be arranged
in chains.
Sketch what you observe under 100X magnification.
3. Typical spirillum - cells are wavy in appearance, but have no particular arrangement.
Sketch what you observe under 100X magnification.
7
Fill in the following chart on bacterial shape and arrangement.
Cocci
Please Draw Each
Please Draw
Each
Bacilli
Diplococcus
Stacked
Tetrad
Chained
Streptococcus
Irregular
Spirillum
Irregular
Staphylococcus
8
Please Draw
Each