Download Bacteria and Viruses

Ch. 19
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Eubacteria
◦ Largest kingdom of living things
◦ Live everywhere
◦ Cell wall contains peptidoglycan
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Archaebacteria
◦ Cell wall lacks peptidoglycan
◦ DNA sequences more similar to eukaryotes
◦ Live in extreme environments
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Shapes
◦ Rod (bacilli)
◦ Spiral (spirilla)
◦ Spherical (cocci)
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Cell walls
◦ Gram-positive stained have peptidoglycan call walls
(violet)
◦ Gram-negative lack peptidoglycan (red)
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Movement
◦ Variety of ways….
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Heterotrophs
◦ Chemoheterotrophs and photoheterotrophs
 majority
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Autotrophs
◦ Photoautotrophs
 Cyanobacteria
◦ Chemoautotrophs
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Obligate aerobes
◦ Require oxygen all the time; aerobic respiration
 Mycobacterium tuberculosis
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Obligate anaerobes
◦ Killed by oxygen; anaerobic respiration
 Clostridium botulinum
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Facultative anaerobes
◦ Can survive with or without oxygen; both types of
respiration
 Eschericia coli
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Binary fission
◦ Mitotic; asexual
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Conjugation
◦ Gene swapping; sexual
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Sporulation
◦ When conditions become unfavorable DNA and a
little cytoplasm is enclosed in an endospore
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Decomposers
Nitrogen fixers
Food industry
Mining
Cleaning oil spills
Pharmaceuticals
Oxy Clean
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Bits of DNA or RNA surrounded by a protein
coat. That’s it.
◦ They come in a variety of shapes and sizes
◦ They must infect a host cell to reproduce.
◦ Bacteriophages are viruses that infect bacteria.
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Viruses enter a host cell and use the cell’s
machinery to reproduce.
◦ In lytic infections the virus reproduces immediately
until the cell bursts.
◦ In lysogenic infections the viral DNA is incorporated
into the host’s DNA as prophage and may remain
dormant for a period of time until reproduction
begins.
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Contain RNA instead of DNA
◦ After infecting a cell the RNA is copied in reverse to
make DNA which is then incorporated into the host
cell’s genome as prophage.
◦ RNA viruses mutate frequently.
 Rhino virus (colds)
 HIV
Are viruses alive?
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Bacteria and viruses can act a pathogens –
disease causing agents (pathos = disease;
gen = generating).
◦ Louis Pasteur helped formulate the germ theory of
disease.
◦ Bacteria cause disease by either using cells for food
or by releasing toxins (poisons) that are harmful.
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Sterilization with heat
Disinfectants
Cold storage
Vacuum packing
Nitrogen/inert gases
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Some target the cell wall of bacteria and
others disrupt protein synthesis.
◦ Antibiotics are specific to the type of bacteria they
act upon.
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Can’t be treated with antibiotics! They don’t
have a cell wall or make proteins…
◦ Best treatment is prevention; once infected it has to
run its course. Symptoms may be treated.
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Vaccines provide some protection and
immunity to bacterial and viral diseases.
◦ More to follow…