Lecture 1
Organisms included in the study
of Microbiology
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1. Bacteria
2. Protozoans
3. Algae
4. Parasites
5. Yeasts and Molds
• Fungi
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6. Viruses
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Bacteriology
 Protozoology
 Phycology
 Parasitology
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Mycology
 Virology
Microorganisms - Microbes - Germs
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All organism other than viruses and
prions are made up of cells
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Viruses
1. Are not cells and are not visible with the
light microscope.
2. Are obligate intracellular parasites.
3. Contain no organelles or biosynthetic
machinery, except for a few enzymes.
4. Contain either RNA or DNA as genetic
material.
5. Are called bacteriophages (or phages) if
they have a bacterial host.
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Viroids
1. Are not cells and are not visible with the
light microscope.
2. Are obligate intracellular parasites.
3. Are single-stranded, covalently closed,
circular RNA molecules that exist as basepaired, rodlike structures.
4. Cause plant diseases but have not been
proven to cause human disease, although
the RNA of the hepatitis D virus (HDV) is
viroid-like.
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. Prions
1. Are infectious particles associated with
subacute progressive, degenerative diseases
of the central nervous system (e.g.,
Creutzfeldt-Jakob disease).
2. Copurify with a specific glycoprotein
(PrP) that has a molecular weight of 27 to 30
kDa. They are resistant to nucleases but are
inactivated with proteases and other agents
that inactivate proteins.
3. Are altered conformations of a normal
cellular protein that can autocatalytically
form more copies of itself.
Classification System
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3 Domains:
• 1. Bacteria
• Unicellular prokaryotes with cell wall containing
peptidoglycan
• 2. Archaea
• Unicellular prokaryotes with no peptodoglycan in
cell wall
• 3. Eukarya
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Protista
Fungi
Plantae
Animalia
5 Kingdoms of Living Organisms
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1. Animalia
2. Plantae
3. Fungi
4. Protista
5. Monera - Bacteria and Cyanobacteria
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Eukaryotic vs. Prokaryotic
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Classification of Microorganism
Domain
Bacteria
Archaea
Eukarya
Archaea
Bacteria (P)/ Bacterium (S)
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Prokaryotes
 Has peptidoglycan cell walls
 Binary fission
 Utilize organic/inorganic
chemicals, or photosynthesis
to obtain energy
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Prokayotic
Lack peptidoglycan
Live in extreme
environments
Include
- Methanogens
- Extreme halophiles
- Extreme thermophiles
Types of Eukaryotes
Protozoa
Algae
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Unicellular eukaryote
 Absorb or ingest organic
chemicals
 May move using
pseudopods, cilia or flagella
 e.g. Amoeba
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Unicellular/multicellular
eukaryote
Has cellulose cell walls
Gain energy through
photosynthesis
Produce molecular and
organic compounds
Domain Bacteria
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Bacteria are singlecelled organisms that
lack a membrane-bound
nucleus. (Prokaryote
also)
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Bacteria are found
almost everywhere on
the planet Earth.
Domain Eukarya
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The cells of all eukaryotes have a membrane-bound
nucleus. Members of the Domain Eukarya are
further categorized into one of four Kingdoms.
(know these kingdoms)
Bacteria - what comes to mind?
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Diseases
Infections
Epidemics
Food Spoilage
Only 1% of all known bacteria cause human
diseases
About 4% of all known bacteria cause plant
diseases
95% of known bacteria are non-pathogens
Microbes Benefit Humans
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1.Bacteria are primary decomposers recycle nutrients back into the environment
(sewage treatment plants)
2. Microbes produce various food products
• cheese, pickles, sauerkraut, green olives
• yogurt, soy sauce, vinegar, bread
• Beer, Wine, Alcohol
3. Microbes are used to produce Antibiotics
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Penicillin
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Mold
• Penicillium notatum
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1928 Alexander Fleming
4. Bacteria synthesize chemicals that our
body needs, but cannot synthesize
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Example: E. coli
• B vitamins - for metabolism
• Vitamin K - blood clotting
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Escherichia coli
• Dr. Escherich
• Colon (intestine)
Microbes do benefit us, but they
are also capable of causing many
diseases
Bacteria
Basic Microbiology
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The science that studies living organisms
that cannot be seen with the naked eye
A microscope is only way to view the
millions of tiny creatures living in our
environment
They are found almost everywhere on
planet
They are on our skin, in the air we breathe,
on every surface we touch, and even inside
our bodies
Microbiology
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Are also referred to as microbes, or more
commonly, germs, especially to laypeople
(layperson: one not in the field – in this
case, those without a science background)
Usually do not notice microorganisms until
they cause physical illness
We often forget microbes play beneficial
role in human health; benefits are greater
than problems created by microbes
Problems v. Benefits
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PROBLEMS
• Various infections in human beings
and animals are caused by
microorganisms
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BENEFITS
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They prevent exposure to other
harmful microorganisms
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They support production of
bread, cheese, yogurt, beer, and
several other foods and
beverages
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They contribute to health of soil
for farming
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They aid in purifying waste water