BIOL 142 Chapter 27 Study Guide for TEST 2

BIOL 142 Chapter 27 - – phage conversion is when phenotype of host is changed Induction = switch from the lysogenic cycle to the lytic cycle HIV

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BIOL 142: Study Guide for TEST # 2 Chapter 27 - Viruses Viruses are NOT living things because they are not made of cells and cannot reproduce on their own; they are chemical parasites of living things Structure: All viruses have 2 major components: DNA or RNA + capsid (some also have enzymes inside or an envelope on the outside); 2 common shapes of viruses – helical and icosahedral (some have more complex shapes) RNA viruses – single-stranded RNA, replicate in cytoplasm ( retroviruses convert RNA to DNA before replicating); DNA viruses – double-stranded DNA, replicate in nucleus Host range – types of organisms infected; Tissue tropism – types of cells infected Lytic Cycle – virulent cycle (kills cells and causes symptoms) Steps of the cycle: - adsorption - penetration - synthesis - assembly - release Lysogenic Cycle – temperate cycle (virus incorporated into host’s genome and is dormant – no symptoms)
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Unformatted text preview: – phage conversion is when phenotype of host is changed Induction = switch from the lysogenic cycle to the lytic cycle HIV causes AIDS – the virus targets helper T cells; the cycle includes 8 years of dormancy before symptoms are observed in patients – treating HIV could involve blocking or diabling host cell receptors or blocking replication of the virus in infected cells Influenza (the flu) – difficult to treat because of quick evolution of new strains with different envelopes and emergence of new strains that have extended their host range Viruses are known to cause about 15% of cancer in humans (viruses cause changes in oncogenes or tumor-suppressor genes) – for example, the HPV virus causes the majority of cases of cervical cancer....
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This note was uploaded on 09/18/2011 for the course BIO 142 taught by Professor Jarrell during the Spring '11 term at Delgado CC.

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BIOL 142 Chapter 27 - – phage conversion is when phenotype of host is changed Induction = switch from the lysogenic cycle to the lytic cycle HIV

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