Lecture3 Bacteria, Archaea, Viruses

Lecture3 Bacteria, Archaea, Viruses - Lecture 3 Marine...

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Marine Viruses, Archaea, Bacteria Lecture 3 Suttle, 2005 Könneke et al. 2005 Rappé et al. 2002
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Marine Viruses “Agents of microbial mortality” thus play a role in cycling of organic matter in the oceans Abundant: ~10 8 per ml in productive coastal waters ; numbers correlate with system productivity, bacterial numbers and chl a Very abundant in marine nearshore surface sediments (10 8 -10 9 per cm 3 ) Contain ~200 Mt of carbon (assuming 0.2 fg of carbon in each virus), equal to carbon in 75 million blue whales Suttle (2005) Nature Vol. 437
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DNA or RNA protein coat sheath base plate tail fiber Virus = “noncellular infectious agent” Consists of genetic material (DNA or RNA) surrounded by a protein coat Cannot reproduce by itself; its genetic material must enter a host cell, then “directs the host cell’s biosynthetic machinery into making many new viruses” Diverse viruses affect organisms of all kingdoms ~200 nm total length
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Curtis Suttle, Nature 2005 Marine Bacteriophages a. Myoviruses –contractile tails, lytic, commonly isolated, broad host range b. Podoviruses -short, non-contractile tail, lytic, narrow host range c. Siphoviruses – long, flexible tail, commonly isolated, intermediate host range 50 nm
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There are five basic steps in the multiplication of viruses: 1. Attachment : the virus recognizes and becomes attached to host cell. 2. Penetration : DNA, or RNA, alone (or whole virus) enters cytoplasm. 3. Replication and synthesis : viral genes direct host cell into replicating viral nucleic acids, synthesizing viral proteins. 4. Assembly : synthesized components are put together into new infectious particles. 5. Release : new virus particles are released from the infected cell immediately, through cell lysis, or after a “latent” period, during which time the virus incorporates its own genetic material into the host’s, is passed on when the host replicates. These are the “lytic” vs “lysogenic” pathways of replication.
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This note was uploaded on 02/22/2012 for the course MSCI 102 taught by Professor Benner during the Spring '10 term at South Carolina.

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Lecture3 Bacteria, Archaea, Viruses - Lecture 3 Marine...

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