Transcript Bacteria and Viruses - Crestwood Local Schools

Chapter 19 Bacteria and Viruses
19-1 BACTERIA
19-2 VIRUSES
19-3 DISEASES
CAUSED BY BACTERIA
AND VIRUSES
19-1 Bacteria
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Bacteria are prokaryotes- unicellular
organisms that lack a nucleus.
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Classification was the Kingdom Monera
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Now, in two separate Kingdoms:
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Eubacteria
Archaebacteria
Bacteria
What’s the Difference?
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Eubacteria- new bacteria
 Example: Escherichia coli (E. coli)
 Found water, land, on and in us.
Archaebacteria- ancient bacteria
 Examples: Methanogens
 Found in harsh environments:
 thick mud, digestive tracts of
animals, hot springs
Identifying Prokaryotes
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Shape
 Cocci – spherical
 Bacilli – rod
shaped
 Spirilla - spiral
How do they obtain energy?
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Most are heterotrophs and many are
autotrophs
Types of heterotrophs: “other”
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Chemoheterotrophs (chemical)
Photoheterotrophs (light)
Types of autotrophs: “self”
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Photoautotrophs (surface of lakes, oceans)
Chemoautotrophs (deep ocean)
Growth and Reproduction
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Can divide every 20 minutes!
Two ways to reproduce:
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Binary fission – dividing in half
Conjugation – form bridge and exchange DNA
When conditions become unfavorable:
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Spore formation – help it survive in extreme
conditions, such as heat, dryness, lack of
nutrients.
Binary fission
conjugation
Spore
formation
Importance of bacteria

Decomposers –
 Help ecosystem
recycle nutrients
by breaking down
dead tissue

Help in sewage
treatment
Human Uses
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Used in industry – clean up oil spills
Remove wastes and poisons from water
Make drugs
Used in food
19-2 Viruses
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Viruses are
composed of a core
of DNA or RNA
surrounded by a
protein coat (capsid)
Virus means poison
Virus Structures
Tobacco Mosaic
Virus
T4 Bacteriophage
Head
DNA
Influenza
Virus
RNA
Capsid
RNA
Capsid
proteins
Tail
sheath
Tail
fiber
Surface
proteins
Membrane
envelope
How does a Virus work?
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Proteins of virus bind to receptors on
the surface of a cell.
Cell gets “tricked” into letting the viral
DNA in.
Cell then transcribes and translates
viral genes.
Bacteriaphage- infects bacteria
Viral Replication
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Two different processes can occur:
Lytic Cycle: viral DNA enters host,
copies are made, and cell lyses
(bursts).
Lysogenic Cycle: viral DNA enters host,
viral genes are replicated indefinitely.

Prophage- viral DNA incorporated in cell’s
DNA
The Lytic Cycle...
The Lysogenic Cycle...
Both Cycles...
Retroviruses

Retrovirus- contains RNA as its genetic
information
Genetic info is copied backwards from
RNA to DNA.
“Retro” means “backwards”

Ex. AIDS is caused by a retrovirus (HIV)
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Comparison…
19-3 Diseases caused by Bacteria
and Viruses
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Disease causing agents are pathogens
Bacteria produce disease in one of two
ways:
 Break down cells for food
 Release toxins (poisons)
Examples for food or toxin release
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TB – tuberculosis –
destroys lung
tissue
Strep throat releases toxins
into blood stream
FLU
EBOLA
SMALL
POX
COLD VIRUS
Common Diseases Caused by Bacteria
Section 19-3
Diseases caused by Bacteria
Disease
Pathogen
Prevention
Tooth decay
Streptococcus mutans
Regular dental hygiene
Lyme disease
Borrelia burgdorferi
Protection from tick bites
Tetanus
Clostridium tetani
Current tetanus vaccination
Tuberculosis
Mycobacterium tuberculosis
Vaccination
Salmonella food poisoning
Salmonella enteritidis
Proper food-handling practices
Pneumonia
Streptococcus pneumoniae
Maintaining good health
Cholera
Vibrio cholerae
Clean water supplies
Controlling Bacteria
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Sterilization – using high temperatures
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Disinfectants – chemical solutions
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Food storage and processing – storing
in fridge or cooking food
Preventing Bacterial Disease
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Vaccine – weakened or killed pathogen
 Examples – meningitis, whooping cough
Antibiotics – block the growth and
reproduction of bacteria
 Examples- Penicillin or tetracycline
Common Diseases Caused by Viruses
Diseases caused by Viruses
Section 19-3
Type of Virus
Nucleic Acid
Disease
Oncogenic viruses
DNA
Cancer
Retrovirus
RNA
Cancer, AIDS
Adenoviruses
DNA
Respiratory infections
Herpesviruses
DNA
Chickenpox
Poxviruses
DNA
Smallpox
Viral disease in humans
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Cannot be treated with antibiotics
Vaccines
 Examples – polio, measles, mumps,
chicken pox, hepatitis b