Transcript Chapter 18 Viruses and Bacteria

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Pages 476 - 495
• Non-living particles that can’t reproduce
• nucleic acids (DNA or RNA)
• enclosed in a protein coat
• Smaller than the smallest bacterium
• Do replicate on their own
• Must have a host
• Don’t carry out respiration, develop or grow
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Have to have a host to replicate
Found soil, air water
Can mutate to become more dangerous
Bacteriophages infect bacterial cells
All living organisms can contract viruses
Some are species specific – HIV only affects humans
~~Influenza, smallpox, HIV, Herpes I and
Herpes II
• Lytic Cycle
• Lysogenic Cycle
• A virus takes over a host’s genetic material
• Uses its structures and energy to replicate many viruses
• The cell bursts (Lysis) and viruses spread
Step
1
Summary
The lytic bacteriophage virus attaches itself to the bacterial cell.
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Lytic
Cycle
2
The virus injects the nucleic acid into the cell.
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3
When all the nucleic acid is injected they begin to replicate, and the
useless original capsid and tail are detaches from the cell.
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4
The viruses grow using the nutrients of the bacterial cell.
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5
When viruses are mature, they come out of the cell, destroying it, and
start to infect other cells.
** The virus’s nucleic acid (DNA/RNA) is integrated
into the host cell’s chromosome
** The cell is then called a provirus
** The virus lay “dormant” as the cell reproduces itself
After the virus has inserted its genetic material (Step 1)
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Tobacco Mosaic virus causes leaves to turn
yellow and can’t be sold at market
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Herpes Zoster (chicken pox), Herpes simplex I
(cold Sores), herpes simplex II (Genital
Herpes), and hepatitis B (affects liver)
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RNA viruses—RNA being their only
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HIV that causes the disease AIDS
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Infects white blood cells (remember B and T
Cells!!!)
• Released into the blood stream by
exocytosis and infect other white blood
cells.
• Viruses linked to cancer disrupt mitosis
• HPV is the most common
• Human Papilloma Virus causes
genital warts and accounts for about
76% of cervical cancers
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Archaebacteria – The extremist; Oldest; saltloving; heat-loving
Eubacteria
 Some are photosynthetic - photosynthesis
 Some undergo chemosynthesis – break down
surrounding organic compounds for food
 Some are heterotrophs – “eat” their own food
Binary Fission
Conjugation
Type of Reproduction
Asexual
Sexual
-------------------------------------------------------------------------------------------How it Happens
One bacterium
one bacterium
makes a copy of
transfers
its chromosomes
chromosomes to
and splits into two
another bacterium
through pili
----------------------------------------------------------------------------------------------Description of Cells
Genetically
Genetically different
Produced
identical
Pili
Ribosome
Cytoplasm
Chromosome
Flagellum
capsule
Cell
Cell Wall Membrane
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Endospore forms around bacteria during harsh
conditions
Cells grow and reproduce
Can produce toxins
 Botulism (food poisoning), anthrax (lives in soil)
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Can mutate quickly to environmental change and
become more dangerous
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Some make you sick and can bcome antibiotic
resistant
Strep throat
 Food poisoning
 Some Pneumonias
 Lyme disease
 Tuberculosis
 Cavities
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Nitrogen fixation (plant root convert nitrogen
gas into usable nitrogen for the plant)
Return nutrients to soil
Produce oxygen
Production of cheese, yogurt and pickles
E. coli in the intestines
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Used in farming, medicine and food industry