Download 1 (9/6/06)

Adding the class
I anticipate a large number of students trying to add 139.
Welcome to Bio 139
General Microbiology
Amy Rogers, M.D., Ph.D.
Lectures MW 12:00-1:15 PM (section 8)
Labs:
MW 1:30-2:45 PM or
MW 3:00 PM-4:15 PM
Priority:
1. Graduating seniors
2. Other seniors; then juniors, sophomores
3. Open university
Syllabus
Prerequisites
• Best to contact me by email [email protected]
• General biology & organic chemistry
– Bio 10 or 20
– Chem 6B, 20, or 24
• Regular office hour: Wed. 9:00-10:00
– Not a good time for you? ASK me!!!
– MW anytime between 8:30 and 10:30 will usually work for me
• If you are enrolled but lack this
preparation, I will administratively drop you
– Exception: BioSci majors may concurrently
take this class and Chem 20 or 24 upon
request (talk to me or email)
• Do not cram. 1 lecture ~~ 6 hours study
• Get to know my website!
– www.csus.edu/indiv/r/rogersa/
– PowerPoint printouts of all lectures
– Weekly news article assignment
– Exam review sheets & other handouts, problem sets
• Book assignment
• Makeup exam policy: Contact me that day.
Please write your name, year, & best
contact info
(email or phone) on sheet in front.
• Textbook, lab manual, 4 Scantron 882 forms for
the four lecture exams
• If you think you might drop, make up your mind
ASAP and let me know!
• Do not fall behind. Pay close attention to both
lecture & lab schedules for the many exam days
Scope & History of Microbiology, or
WHAT AM I DOING HERE?
Understanding microbiology is crucial to
virtually all disciplines within the life sciences
1. Fundamental processes of all life
{metabolism, genetics, evolution…}
2. Ecology
{nitrogen cycle, decomposition, deep hot biosphere}
Through the testing
center.
Chemistry quiz: Wed. September 13th
– Prepare on your own: read chapter 2; see Ch.2
review PowerPoint at my website
3. Medical microbiology
{although very few microbes are pathogens}
4. Food & industry
{dairy, animal husbandry, biotechnology…}
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MICROBES EXIST EVERYWHERE
Applications
•
Food microbiology
–
•
Soil
fermentation, leavening, pickling; microbes as a food source
Industrial
– Bioremediation, biosynthesis
•
Source of antibiotics & other useful products
•
Research
Air
Tongue
– Microbes are the workhorses of molecular biology
Mass of bacteria on Earth
greatly exceeds the total weight of all other living things
Fungi
Microorganisms:
Who are they?
(singular: fungus)
• Single-celled (Yeasts)
1.
2.
3.
4.
5.
Fungi
Protozoa
Algae
Bacteria
Viruses
Eukaryote
• Multi-cellular (Molds)
Eukaryote
• Eukaryotic
Eukaryote
Prokaryote
• Widely distributed in water and soil as
decomposers of dead organisms
Acellular
• Some structures are not microscopic
• Some are important in medicine
Eukaryotes: have nuclei & other organelles; generally bigger & more complex than prokaryotes
Fungi
Fruiting bodies (mushrooms)
Mold: hyphae & conidia
Fungi: Budding Yeast
6,160 X
Macroscopic structures
http://www.biochem.ucl.ac.uk/~dab/guspix/pages/fungus%20-%202.htm
Microscopic 85 X
Note scars on the right, representing sites of previous budding
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Protists 1:
Protozoa (singular: protozoan)
Amoeba (183X)
• Single-celled
• Eukaryotic
• Found in a variety of water and soil
environments
Examples:
Giardia, Leishmania, Plasmodium (malaria), Paramecium
Protists 2:
Algae (singular: alga)
(paramecium swimming)
• Single-celled
http://micro.magnet.fsu.edu/moviegallery/pondscum/protozoa/paramecium/index.html
(amoeba moving with pseudopodia)
http://micro.magnet.fsu.edu/moviegallery/pondscum/protozoa/amoeba/index.html
• Eukaryotic
• Photosynthetic
• Fresh water and marine environments
Examples:
Diatoms, dinoflagellates
Bacteria
Micrasteria (334X)
(singular: bacterium)
• Single-celled
• Prokaryotes
• Major shapes:
1. Spherical
2. Rod
3. Spiral
cocci (one coccus)
bacilli (one bacillus)
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Viruses
Klebsiella pneumoniae (5,821X)
•
Acellular entities too small to be seen with a
light microscope
•
•
•
Composed of nucleic acid and protein
Obligate intracellular parasites
–
•
Bacteriophages (35,500x)
Visible with electron microscopy
Can only reproduce inside a living cell
Every cell type (including bacteria) has
specific kinds of viruses that can infect it
History of Microbiology
• Endless variety of plagues through human
history {see book choice Plagues & Peoples}
• Black Death (bubonic plague): London, 1660’s
• Smallpox in the New World
• The Great Influenza of 1918 {see book choice Flu}
• But where did such sudden, massive death come from?
An unseen world…
Anton van Leeuwenhoek
• Late 1600’s
• Dutch merchant & “amateur” lens grinder
• Best magnifications ever used (300x)
• First person to SEE the microbial world
“animalcules”
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Chapter 3: Microscopy
Light Microscopes
• Specimen observed using visible light
• Leeuwenhoek: single lens
• problems with focus, various distortions
•Compound Light Microscope: has
multiple lenses (e.g., objective & ocular
lenses)
•Objective lens actually contains multiple
lenses that correct aberrations of color & focus
Light Microscopy
• Resolution: ability to see two things as two things
(instead of one blurry thing)
Iris diaphragm
Resolved
Not resolved
(same magnification)
…is closely related to…
Long
wavelength
Wavelength
Short
wavelength
Same magnification,
Different resolution
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Once you’ve reached about 1000X magnification with a
light microscope, increasing the magnification will not
give you a better image:
resolution is limited by the wavelength of visible light.
To get clear images
at higher magnification,
you must use a shorter wavelength:
Refraction
Light bends when it
passes from one
medium to another of
different optical
density (different
index of refraction)
electron microscopes
Ex. Water vs Air
Using a light microscope:
Immersion Oil
• Microscope specimen is on a glass slide.
• Light passes through glass slide Æ air Æ lens
Light microscopy
• Problem: Most microbes are basically tiny
bags of water
– No color, poor contrast, difficult to see
gets refracted
• At high magnification, this refraction (bending) of the light
blurs the image
• To eliminate refraction between slide and lens:
Eliminate the air, replace with immersion oil
(has same index of refraction as glass)
Dark-field Microscopy
• Regular light microscopy: “bright field”
• Dark field: light does not pass through the
specimen, but is reflected off it
Saccharomyces cerevisiae (yeast) 975X
• Can stain the specimen
• This usually means the specimen must be dead
• Or use special types of light microscopy:
– Dark field, phase contrast, fluorescence
Phase contrast microscopy
• A type of light microscopy
particularly useful for
observing live organisms
• Lenses enhance small
differences in the index of
refraction of various cell
structures
– Perceived as different
degrees of brightness
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Fluorescence microscopy
• Ultraviolet (UV) light
• Beam of electrons instead of a beam of
light
• Focus using electromagnets, not glass
lenses
illuminates the specimen
and excites certain
molecules to emit brilliant
colors (fluoresce)
– Some microbes fluoresce
naturally
– Usually, microbes are
stained with fluorescent
dyes
• Commonly used to identify
organisms
Electron Microscopy
• Large, expensive, difficult to use
• FANTASTIC magnification (up to
500,000x) and resolving power
• Two types: Transmission (TEM) & Scanning (SEM)
Yeast (stained)
Transmission Electron Microscopy
TEM
67,000x
SEM
40,000x
• Excellent for viewing internal cell
structures, and viruses
• Specimen preparation is complex
• Embedded in plastic, cut into ultrathin sections
(slices) with a diamond knife
Scanning Electron Microscopy
• Excellent for viewing cell surfaces in 3D
• Specimen is coated with a thin layer of heavy
metal such as gold, which scatters electrons
Both images show E. coli bacteria
Relevant chapters in
Black’s Microbiology:
• Chapter 1: Overview & History
• Chapter 3: Microscopy
• Course syllabus
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