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Chapter 19 Bacteria and Viruses

19-1 BACTERIA 19-2 VIRUSES 19-3 DISEASES CAUSED BY BACTERIA AND VIRUSES. Chapter 19 Bacteria and Viruses. 19-1 Bacteria. Bacteria are prokaryotes- unicellular organisms that lack a nucleus . Classification was the Kingdom Monera Now, in two separate Kingdoms: Eubacteria

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Chapter 19 Bacteria and Viruses

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  1. 19-1 BACTERIA 19-2 VIRUSES 19-3 DISEASES CAUSED BY BACTERIA AND VIRUSES Chapter 19 Bacteria and Viruses

  2. 19-1 Bacteria Bacteria are prokaryotes- unicellular organisms that lack a nucleus. Classification was the Kingdom Monera Now, in two separate Kingdoms: Eubacteria Archaebacteria

  3. Bacteria

  4. What’s 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

  5. Identifying Prokaryotes • Shape • Cocci – spherical • Bacilli – rod shaped • Spirilla - spiral

  6. 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)

  7. 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.

  8. Binary fission conjugation Spore formation

  9. Importance of bacteria • Decomposers – • Help ecosystem recycle nutrients by breaking down dead tissue • Help in sewage treatment

  10. Human Uses • Used in industry – clean up oil spills • Remove wastes and poisons from water • Make drugs • Used in food

  11. 19-2 Viruses • Viruses are composed of a core of DNA or RNA surrounded by a protein coat (capsid) • Virus means poison

  12. Virus Structures RNA RNA DNA Capsid Head Capsid proteins Tail sheath Tail fiber Surface proteins Membrane envelope Tobacco Mosaic Virus T4 Bacteriophage Influenza Virus

  13. 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

  14. 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 cell’s DNA

  15. The Lytic Cycle...

  16. The Lysogenic Cycle...

  17. Both Cycles...

  18. 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)

  19. Comparison…

  20. 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)

  21. Examples for food or toxin release TB – tuberculosis – destroys lung tissue Strep throat - releases toxins into blood stream

  22. FLU EBOLA SMALL POX COLD VIRUS

  23. 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 Proper food-handling practices Maintaining good health Clean water supplies Tooth decay Lyme disease Tetanus Tuberculosis Salmonella food poisoning Pneumonia Cholera Streptococcus mutans Borrelia burgdorferi Clostridium tetani Mycobacterium tuberculosis Salmonella enteritidis Streptococcus pneumoniae Vibrio cholerae

  24. Controlling Bacteria Sterilization – using high temperatures Disinfectants – chemical solutions Food storage and processing – storing in fridge or cooking food

  25. Preventing Bacterial Disease Vaccine – weakened or killed pathogen Examples – meningitis, whooping cough Antibiotics – block the growth and reproduction of bacteria Examples- Penicillin or tetracycline

  26. 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 Herpesviruses Poxviruses DNA RNA DNA DNA DNA

  27. Viral disease in humans Cannot be treated with antibiotics Vaccines Examples – polio, measles, mumps, chicken pox, hepatitis b

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