Lecture 15

Lecture 15 - LS3 MOLECULAR BIOLOGY LECTURE 14 Overview...

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LS3 MOLECULAR BIOLOGY LECTURE 14 Overview    Dr. Randolph Wall             Reading:  Watson et al.  681-684 
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biosynthetic processes Viral genomes can be DNA or RNA, single- or double-stranded, linear or circular DNA viruses use host enzymes,  dsDNA   dsDNA  RNA viruses encode their own replication enzymes or carry them in virions RNA-directed RNA polymerases (e.g., flu viruses) RNA     RNA Reverse transcriptase RNA     DNA  (e.g., retroviruses) Virus particles (virions) organized in two basic ways: helical rod-shaped vs. icosahedral (20-sided)  spherical-shaped.  Some also have lipid envelopes surrounding internal viral nucleocapsids Viruses usually only infect specific host cells - host range limited to cells with interactive surface receptors or injection of viral nucleic acid into cell Second step is viral replication inside infected cell Third step is release of progeny virus from cell The Features and Life Cycles of Viruses
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Lytic Replication Cycle of E. coli Bacteriophage T4 From Lodish et al (2004) Molecular Cell Biology.  W.H. Freeman & Co.
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Some of the Possible Outcomes of Animal Virus  Infections = no virus production    EXAMPLES: Retroviruses,    SV40 Adenoviruses, Poliovirus Hepatitis Herpesviruses
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Life Cycle of Retrovirus HIV in a T helper Cell Proviral DNA
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          HIV polyprotein protease cleavage     -> viral proteins
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RNA cDNA Viral RNA Reverse  transcriptase AZT ddI Viral polyprotein HIV Inhibitors Protese inhibitors Protease Viral proteins
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Central Dogma - Modified DNA          RNA      Protein transcription translation  RNA reverse  transcription RNA-directed RNA synthesis Reverse Transcriptase is a powerful tool for recombinant DNA cloning (more  on cDNA cloning later)  RNA genomes are more prone to accumulate mutations because reverse  resistance to anti-viral therapies, produce mutant viruses in diseases (e.g., production of new flu stains, more on this later)
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LS3 MOLECULAR BIOLOGY LECTURE 15 May 20, 2008   Dr. Randolph Wall                  Reading:  Watson et al.  647-653
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Molecular biology employs techniques used in biochemistry,  genetics and a collection of techniques commonly referred to 
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Lecture 15 - LS3 MOLECULAR BIOLOGY LECTURE 14 Overview...

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