Chapter 19 Bacteria and Viruses

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Chapter 19 Bacteria and Viruses

• 19-1 BACTERIA
• 19-2 VIRUSES
• 19-3 DISEASES
• CAUSED BY BACTERIA AND VIRUSES

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19-1 Bacteria

• Bacteria are prokaryotes- unicellular organisms
  that lack a nucleus.
• Classification was the Kingdom Monera
• Now, in two separate Kingdoms
• Eubacteria
• Archaebacteria

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Bacteria
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Whats the Difference?

• 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

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Identifying Prokaryotes

• Shape
• Cocci spherical
• Bacilli rod shaped
• Spirilla - spiral

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How do they obtain energy?

• Most are heterotrophs and many are autotrophs
• Types of heterotrophs other
• Chemoheterotrophs (chemical)
• Photoheterotrophs (light)
• Types of autotrophs self
• Photoautotrophs (surface of lakes, oceans)
• Chemoautotrophs (deep ocean)

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Growth and Reproduction

• Can divide every 20 minutes!
• Two ways to reproduce
• Binary fission dividing in half
• Conjugation form bridge and exchange DNA
• When conditions become unfavorable
• Spore formation help it survive in extreme
  conditions, such as heat, dryness, lack of
  nutrients.

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Binary fission
conjugation
Spore formation
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Importance of bacteria

• Decomposers
• Help ecosystem recycle nutrients by breaking down
  dead tissue
• Help in sewage treatment

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Human Uses

• Used in industry clean up oil spills
• Remove wastes and poisons from water
• Make drugs
• Used in food

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19-2 Viruses

• Viruses are composed of a core of DNA or RNA
  surrounded by a protein coat (capsid)
• Virus means poison

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Virus Structures
Tobacco Mosaic Virus
T4 Bacteriophage
Influenza Virus
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How does a Virus work?

• 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

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Viral Replication

• 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 cells DNA

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The Lytic Cycle...
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The Lysogenic Cycle...
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Both Cycles...
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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
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19-3 Diseases caused by Bacteria and Viruses

• Disease causing agents are pathogens
• Bacteria produce disease in one of two ways
• Break down cells for food
• Release toxins (poisons)

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Examples for food or toxin release

• TB tuberculosis destroys lung tissue
• Strep throat - releases toxins into blood stream

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FLU
EBOLA
SMALL POX
COLD VIRUS
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Common Diseases Caused by Bacteria
Section 19-3
Diseases caused by Bacteria
Disease
Pathogen
Prevention
Regular dental hygiene Protection from tick
bites Current tetanus vaccination Vaccination Prop
er food-handling practices Maintaining good
health Clean water supplies
Tooth decay Lyme disease Tetanus Tuberculosis Salm
onella food poisoning Pneumonia Cholera
Streptococcus mutans Borrelia burgdorferi Clostrid
ium tetani Mycobacterium tuberculosis Salmonella
enteritidis Streptococcus pneumoniae Vibrio
cholerae
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Controlling Bacteria

• Sterilization using high temperatures
• Disinfectants chemical solutions
• Food storage and processing storing in fridge
  or cooking food

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Preventing Bacterial Disease

• Vaccine weakened or killed pathogen
• Examples meningitis, whooping cough
• Antibiotics block the growth and reproduction
  of bacteria
• Examples- Penicillin or tetracycline

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Common Diseases Caused by Viruses
Section 19-3
Diseases caused by Viruses
Type of Virus
Nucleic Acid
Disease
Cancer Cancer, AIDS Respiratory
infections Chickenpox Smallpox
Oncogenic viruses Retrovirus Adenoviruses Herpesvi
ruses Poxviruses
DNA RNA DNA DNA DNA
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Viral disease in humans

• Cannot be treated with antibiotics
• Vaccines
• Examples polio, measles, mumps, chicken pox,
  hepatitis b