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Selected Parts of Ch 18 Viruses and expanding on Bacteria Concepts Bacteria Reading

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Selected Parts of Ch 18 Viruses and expanding on Bacteria Concepts Bacteria Reading

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    1. Selected Parts of Ch 18 (Viruses) and expanding on Bacteria Concepts (Bacteria Reading)

    2. Virus! Viruses are tiny…requiring electron microscopes to be seen fully Viruses are not considered alive for two reasons: #1) they can crystalize (nothing alive can do this) #2) they cannot reproduce on their own, nor do they have an energy metabolism

    4. Parts of a Virus Capsid= “head”…protein that encloses viral genome…depending on type it may be polyhedral or rod shaped or more complex Genome= viruses can have double stranded DNA OR single stranded DNA or single stranded RNA May have viral envelope (additional part)…these cloak the capsids. Material derived from capsid

    7. Where did something like this come from?! We don’t know. But we do have some hypothesizes: #1) Maybe they had cellular origins. Perhaps they were once part of cells, but they somehow escaped and were able to exist outside of cells #2) Maybe they evolved independently from cells from primitive self-replicating cells. As cells evolved, viruses followed. #3) Maybe they evolved from transposons (“jumping genes”) that acquired a coat protein and were able to jump to other genes. #4) Maybe they are actually degenerative life forms (regressive evolution) that retained genetic information required for reproduction

    8. Transposon

    9. The Key to Viruses are their Reproductive Strategies Viruses MUST have a host to replicate in Viruses identify host by a “lock-and-key fit”…most are specific, some are more broad such as swine flu (which can attack swine and humans)

    10. LYTIC CYCLE

    11. LYSOGENIC CYCLE

    12. Animation! http://highered.mcgraw-hill.com/sites/0072556781/student_view0/chapter17/animation_quiz_2.html

    13. Some viruses have RNA instead of DNA RNA viruses must be equipped with something (packaged within their capsid) called reverse transcriptase…and enzyme (see the –ase) that transcribes DNA from an RNA template (allowing RNA?DNA)…why? Good example of a RNA virus? AIDS

    14. (ex of an RNA virus) HIV Believed to have Evolved from Chimpanzees (SIV)

    15. Example of an RNA Virus: HIV

    16. HIV is attracted to T Cells due to its attraction for a CD4 protein on its surface (selectivity for immune cells)

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