9-2 Biology - 2 9/2 Thurs. Biology 7 Quiz on the 22 phyla...

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2 9/2 Thurs. Biology 7 Quiz on the 22 phyla listed here Viruses (protein, nucleic acid) - like transposons (jumping genes) - viroids (nucleic acids only) - prions (proteins only) o infectious proteins Virus - structure o nucleic acid core made of DNA or RNA o protein coat (capsid) antibodies attack the capsid o membranous envelope covers the capsid not in every virus made with phospholipid bilayers, made of plasma membrane of the host Classification of viruses - Type of genetic materials in the viruses o DNA or RNA o Double or single stranded - Shape of the virus - Symmetry of the capsid - Size of the capsid - Presence or absence of envelope - Type of host Phages - attack bacteria - 2 phases o lytic phase rapidly reproducing most viruses exhibit only this phase How it works: Phage attaches to the bacteria and inserts its genetic materials Host RNA polymerase attaches to promoter regions of the early genes
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o Purpose of the early genes Code for proteins that shut down the host transcription Stimulate viral genome replication Stimulate late gene transcription Nuclease enzymes digest host chromosomes to provide nucleotides for the viral genome Late genes has 3 functions o code for proteins that catalyze the production of the protein capsid, o that package the virions (virus particles), o and lyse the host cell to release the virions o lysogenic phase phage binds to the bacterium and injects its genetic material phage DNA integrates into the bacterial chromosome and becomes a non-infective prophage (DNA in the host cell) chromosomes with the integrated prophage replicate. This can continue for several generations eventually the prophage separates from the host chromosome and enters into the lytic phase
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This note was uploaded on 07/14/2011 for the course BIO 7 taught by Professor Olsen during the Spring '11 term at East Los Angeles College.

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9-2 Biology - 2 9/2 Thurs. Biology 7 Quiz on the 22 phyla...

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