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Chapter 18 Viruses and Bacteria

Explore the fascinating world of viruses and bacteria, from their structures and replication cycles to their impacts on health and the environment. Discover how viruses mutate and become more dangerous, and learn about the various types of bacteria and their adaptations. Find out how bacteria can be both harmful and helpful to humans, and delve into the intricate relationship between viruses and cancer. This comprehensive chapter provides valuable insights into these microscopic organisms.

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Chapter 18 Viruses and Bacteria

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  1. Chapter 18 Viruses and Bacteria • Pages 476 - 495

  2. A Rhinovirus

  3. The Flu

  4. What is a Virus?? • 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

  5. Viruses • Don’t carry out respiration, develop or grow • 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

  6. Structure of Bacteriophage that Infects Bacteria

  7. Bacteriophage

  8. Bacteria Phages Amplified with Electron Microscope

  9. Virus Amplified by Electron Microscope

  10. Viruses Replicate (NOT real reproduce)

  11. Viral Replication Cycles • Lytic Cycle • Lysogenic Cycle

  12. Lytic 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

  13. Lytic Cycle

  14. Lysogenic Cycle ** 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

  15. Lysogenic Cycle After the virus has inserted its genetic material (Step 1)

  16. Replication ActivityCompared to a Factory

  17. Types of Viruses

  18. Tobacco Mosaic virus causes leaves to turn yellow and can’t be sold at market

  19. Proviruses(Undergo the lysogenic cycle) • Herpes Zoster (chicken pox), Herpes simplex I (cold Sores), herpes simplex II (Genital Herpes), and hepatitis B (affects liver)

  20. Retrovirus • RNA viruses—RNA being their only • HIV that causes the disease AIDS

  21. Retrovirus HIV • Infects white blood cells (remember B and T Cells!!!) • Released into the blood stream by exocytosis and infect other white blood cells.

  22. HIV

  23. Cancer and Viruses • 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

  24. Bacteria

  25. Bacteria - Prokaryotes • Archaebacteria – The extremist; Oldest; salt-loving; heat-loving • Eubacteria • Some are photosynthetic - photosynthesis • Some undergo chemosynthesis – break down surrounding organic compounds for food • Some are heterotrophs – “eat” their own food

  26. Bacteria Reproduction 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

  27. Bacteria Pili Ribosome Cytoplasm Chromosome Flagellum Cell Membrane capsule Cell Wall

  28. Bacteria Adaptations • Endospore forms around bacteria during harsh conditions • Cells grow and reproduce • Can produce toxins • Botulism (food poisoning), anthrax (lives in soil) • Can mutate quickly to environmental change and become more dangerous

  29. Harmful • Some make you sick and can bcome antibiotic resistant • Strep throat • Food poisoning • Some Pneumonias • Lyme disease • Tuberculosis • Cavities

  30. Helpful to Humans • 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 • Used in farming, medicine and food industry

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