VIRUSES
(What the heck are they?)
The Common Cold Virus
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Oh Goodness, My E. coli has a Virus!
Viruses and Bacteria
It's easy to mix these up since compared to us, both are
VERY SMALL.
Great link for size comparison!
Source: http://www.cellsalive.com/phage.htm
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The basics  Viruses are:
 non-living
 much smaller than the smallest cell
 pieces of genetic coding (DNA or RNA)
“gift-wrapped” in a protein coat
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Diversity of Capsids
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Diseases caused by viruses include:
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Common cold
Flu
Polio
Rabies
Herpes (chickenpox,cold sores, genital)
Warts
Measles, Mumps
Ebola
AIDS
Viruses cannot be killed with antibiotics because they are not alive!
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Antibodies attacking AIDS Virus
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Diversity of Life
Introduction to Prokaryotes
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Figure 13.27a
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Figure 13.27b
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Prokaryote Diversity
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• Two types of Prokaryotic organisms:
Eubacteria (bacteria) and Archaea
Prokaryotes
Domain Bacteria
Domain Archaea
(e.g., extremophiles)
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Visual Summary
Archaea – Thermophiles in a Nevada geyser.
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Archaea in a hot spring.
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Archaea – Halophiles
in seawater evaporating
ponds near San
Francisco Bay.
Salinity increases from
3% to 20% during the
production of salt.
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Archaea
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(a.k.a. “Archaeabacteria)
 Prokaryotic (like eubacteria)
 Biochemically resemble eukaryotic cells
 Believed to be the ancestors of eukaryotic cells
Today: only live in harsh environments
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(Bacteria Review)
What do you already know about
bacteria??
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Bacteria on the tip of
a pin.
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• Major Episodes in the History of Life
Millions of years ago
475
570
1,000
1,700
2,500
3,500
4,500
Major Episode
Plants and fungi colonize land
All major animal phyla established
First multicellular organisms
Oldest eukaryotic fossils
Accumulation of atmospheric 02
Oldest prokaryotic fossils
Origin of Earth
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Visual Summary
ALL CELLS have
• Plasma membrane
• DNA
• ribosomes
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Generalized structure of bacteria cell
Figure4.5x2
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Bacterial shapes: cocci, rods, spirals
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Cyanobacteria or “blue-green algae”
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Bacterial colonies growing in culture.
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Detriments to Humans
• Bad breath, tooth decay
• Food poisoning
• Some are pathogenic
pathogenic –
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Some Diseases caused by bacteria
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Strep throat
Cholera
Tubercolusis
“the plague”
Anthrax
Toxic shock syndrome
Syphilis, Gonorrhea,
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How cure bacterial infections?
(Antibiotics)
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Discussion Question:
Should we drop “bacteria bomb?”
• Are there benefits to
bacteria that outweigh
their detriments to
humans????
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Benefits of Bacteria
• Decomposers!  chemical cycling
• Cyanobacteria were original producers of oxygen
atmosphere  ozone
• Origins of mitochondria & chloroplasts
• Aid humans in digestion (E. coli)
• Allow cows to digest cellulose (grass)
 milk, ice cream, hamburgers!
• Lactic acid fermentation
(yogurt, buttermilk, sauerkraut)
• bioremediation
• Nitrogen “fixers”
(to be explained in Unit IV!)
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