Transcript viruses and bacteria

UNIT 8:Chapter 19
Bacteria and Viruses
BACTERIA
The beautiful colors in this sulfur
spring are caused by the bacteria
that live in it. Bacteria can survive
in extreme habitats.
Prokaryote Review
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Mostly single -celled
No nucleus
 Circular chromosomes
 Cell walls
 Reproduce mostly asexually
 Anaerobic or aerobic
 Heterotrophic or autotrophic
Archaebacteria
 Methane
producers –
anaerobic
 Halophiles
 Halo
= salt
 Philia = love
 Thermophiles
 Thermo = heat
THESE BACTERIA CELLS HAVE
PEPTIDOGLYCAN IN THEIR CELL WALLS TO
Hey you, Bacteria, I love your shape!!!
(Eubacteria)
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Shapes: Cocci, Bacilli, and Spirilla
How are these words associated
with bacteria?
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Baking soda
Yogurt
Tooth decay
Vitamins
Road kill
Bacteria are Named by Shape
 Coccus
(ball-shaped)
 Streptococcus
 Bacillus
(rod-shaped)
 Clostridium
 Spirilli
mutans
botulinum
(spiral-shaped)
 Treponema
palladium
Prokaryotic Body Plan
DNA
capsule
bacterial flagellum
Figure 21.3
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pilus
plasma
membrane
cell wall
ribosomes in
cytoplasm
cytoplasm
Bacterial Shapes
coccus
bacillus
spirillum
In-text figure
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Prokaryotic Fission - 1
bacterial
chromosome
Bacterium before
DNA replication
DNA replication
begins
Figure 21.7
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Prokaryotic Fission - 2
parent DNA
molecule
DNA replication
completed
DNA copy
Membrane growth
moves DNA
molecules apart
Figure 21.7
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Prokaryotic Fission - 3
New membrane and
cell-wall material
deposited
Cytoplasm
divided in two
Figure 21.7
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nicked plasmid
in donor cell
Conjugation
Transfer of plasmid
Figure 21.8
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conjugation tube
to recipient cell
Rhizobium
Bacteria Good??
BACTERIA CAN HELP THOSE WHO ARE INSULIN DEFICIENT (SOME
DIABETICS). THIS IS DONE WHEN THE BACTERIA’S DNA COMBINES
WITH INSULIN PRODUCING GENES FROM HUMAN.
VIRUSES
Are viruses alive?
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Only 1 characteristic of life:
reproduction
Can only reproduce inside a host
cell!
Process or reproduction = lytic cycle
Like bacteria, viruses produce
disease by disrupting the body’s
normal equilibrium (homeostasis).
Figure 19-11 Viruses and Cells
Section 19-2
Figure 19-10 Lytic and Lysogenic Infections
Common Diseases Caused by Viruses
Section 19-3
Diseases caused by viruses:
Type of Virus
Nucleic Acid
Disease
Oncogenic viruses
DNA
Cancer
Retrovirus
RNA
Cancer, AIDS
Adenoviruses
DNA
Respiratory infections
Herpesviruses
DNA
Chickenpox
Poxviruses
DNA
Smallpox
Lytic
Pathway
Lysis of host cell is induced;
infectious particles escape.
Tail fibers and other parts
are added to coats.
Virus particles bind to wall of suitable host.
Viral genetic material enters cell cytoplasm.
Viral protein molecules are assembled
into coats; DNA is packaged inside.
Viral DNA directs host
machinery to produce viral
proteins and viral DNA.
Stepped Art
Fig. 21.20 Page
358
Lysogenic
Pathway
Viral DNA usually becomes
integrated into the bacterial
chromosome.
Prior to prokaryotic fission, the
chromosome and integrated
viral DNA are replicated.
Viral DNA is excised from
chromosome and cell
enters lytic pathway.
After binary fission, each
daughter cell will have
recombinant DNA.
Stepped Art
Fig 21.20 (2)
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Viral Body Plans
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Complex virus
(bacteriophage)
Genetic material is
DNA or RNA
Coat is protein
Helical virus
Polyhedral virus
Fig. 21.18
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LYTIC CYCLE-virus replication
Enveloped Virus (HIV)
viral protein
lipid envelope
(derived from host)
viral RNA
reverse transcriptase
viral coat (proteins)
Fig. 21.18
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Video
Lytic and Lysogenic Cycles
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Click the image to play the video
segment.
Virus Nucleic Acid
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DNA viruses – stable, do not mutate
rapidly
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Single-stranded or double-stranded
Smallpox, Hepatitis B
RNA viruses – mutate rapidly,
unstable
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Single-stranded or double-stranded
HIV, Rhinovirus
Evolution and Disease
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Host and pathogen are coevolving
If a pathogen kills too quickly, it
might disappear along with the
individual host
Most dangerous if pathogen
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Is overwhelming in numbers
Is in a novel host
Is a mutant strain
Nature of Diseases
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Contagious disease pathogens must
directly contact a new host
Epidemic
Pandemic (AIDS)
Sporadic
Endemic
New Threats
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Emerging Pathogens
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Ebola virus
Monkeypox virus
Drug-resistant strains
Food poisoning
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E. coli
Salmonella