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Chapter 18 Bacteria and Viruses

Chapter 18 Bacteria and Viruses. What is a virus?. Is an infectious particle made of up a protein capsid and DNA or RNA but never both It cannot replicate on its own but needs to be in a living host cell to be replicated Causes disease such as AIDS, Colds, Polio, Flu…. What are bacteria?.

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Chapter 18 Bacteria and Viruses

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  1. Chapter 18Bacteria and Viruses

  2. What is a virus? • Is an infectious particle made of up a protein capsidand DNA or RNA but never both • It cannot replicate on its own but needs to be in a living host cell to be replicated • Causes disease such as AIDS, Colds, Polio, Flu…

  3. What are bacteria? • Are prokaryotic, unicellular microorganisms. • Like viruses, may be pathogens (disease causing agents) • Causes diseases such as Lyme, Staph infections, Strep throat, Syphilis,

  4. What is the structure of a bacteriophage virus • Like all viruses, it has a protein capsid, that houses either DNA or RNA • It has tail fibers for attachment onto the surface of the host bacteria Capsid DNA or RNA Tail fibers

  5. Discuss the Lytic infection pathway • Virus gains entry, gets replicated then gets out • Colds, the flu,SARS, measles…

  6. Discuss a Lysogenic infection pathway • Viral DNA becomes incorporated into the host’s DNA, maybe forever or may come out at some time. • HIV, Cold sores, Chickenpox/Shingles or any herpes virus like mono... DNA enters DNA incorporates DNA is replicated Cells reproduce

  7. What is the difference between the Lytic and Lysogenic cycles? • Lytic infection occurs immediately many times with the destruction of the host cell. • Lysogenic infection does not ever have to progress past incorporation of the DNA. One can be HIV + forever or may never get Shingles

  8. Vaccines, the magic shots! • Vaccines are substances that stimulate the immune system to produce antibodies against a particular pathogen (disease causing agent) • Using made from a weakened version of a virus or parts of the virus that cannot cause the disease. • Measles, mumps, rubella • Chicken pox/Shingles • HPV • Hepatitis • Rabies (for your pet, not you!) • West Nile • Flu (influenza)

  9. What are the 3 shapes of bacteria? Bacillus - rod Spirilla - spiral Coccus - round

  10. Label the main parts of a bacterial cell Pili Ribosomes Flagella DNA

  11. Methods of reproduction in Bacteria • Asexually • Binary fission – one round of mitosis • No genetic variation occurs • Every cell is a clone of the original

  12. “Sexually” • Conjugation – duplication and then transfer of and extra piece of DNA • Endospores – specialized thick walled protective cells to allow bacteria to survive adverse conditions like cold or drought • Tetanus bacteria is one of these

  13. How are bacteria mutualisticsymbionts in us • Found along our entire digestive system • Helps us to: • break down food • provide essential vitamins and minerals • protecting us from other harmful pathogens • They get a place to live and food from us

  14. Bacteria’s role in the ecosystem • Decomposers • Producers – photosynthetic bacteria • Nitrogen fixation – in legumes from nitrogen fixing bacteria to take atmospheric nitrogen and convert it into ammonia (NH3)

  15. What are antibiotic & why won’t it work with the cold or flu? • Antibiotics are chemicals that kill or slow down the growth of bacteria until the immune system can produce antibodies • Produced by bacteria and fungus – Penicillin • Stops the production of cell walls. • Since viruses don’t have cell walls and aren’t living, antibiotics are useless on them.

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