bio 315 chapter 13

bio 315 chapter 13 - Chapter 13: Viruses: Replication...

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Chapter 13: Viruses: Replication Strategies of Bacteriophages Viruses – General Principles; Focus on Bacterial Viruses Non-living obligate intracellular parasites OR the simplest living things there are (depends upon your definition of “life”) Viruses They ALWAYS contain nucleic acid (DNA or RNA) and a protein coat (the “capsid”), and SOMETIMES have an envelope made of lipids, carbohydrates, and proteins (basically similar in structure to an enhanced plasma membrane, but with DIFFERENT FUNCTION!) Viruses are very specific regarding the types of cells they can infect; they generally infect certain types of cells in a particular species – host range . They can only be seen by electron microscopy and range from 20 – 1,000 nM in length. Viral Structure A virion is a mature, infective particle consisting of nucleic acid and protein coat (and envelope depending upon the species). Viruses can have many arrangements of nucleic acids as their genomes. They may have either RNA or DNA (never both), and the nucleic acid may be single or double-stranded, and linear or circular. The protein coat is referred to as the CAPSID, which consists of subunits called capsomeres . If the virus has an envelope, spikes are usually present (carbohydrate-lipid complexes whose function we will discuss later.) General Morphology Helical Viruses – (capsomeres are assembled in a helical configuration) usually resemble long rods, and
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This note was uploaded on 04/07/2008 for the course BIO 315 taught by Professor Schmidt during the Spring '08 term at SUNY Stony Brook.

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bio 315 chapter 13 - Chapter 13: Viruses: Replication...

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