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Unformatted text preview: We have Single stranded DNA type. Strand can be sense strand or a negative sense strand. We have RNA Viruses: 1. Positive sense strand RNA = mRNA 2. We have negative sense strand RNA, which must make a + strand, or do reverse transcription = Retroviridae = HIV and cancer causing viruses. 3. RNA viruses mutate like crazy. They don't have the repair enzymes available to them for replication. Also, virus is so small that RNA would have to be significantly larger to make an enzyme. One 100 amu amino acid needs 1000 triplet to code for it. What restriction does that place on the virus? This is why protein coat is usually made of 2 or 3 proteins that are made by the genome over and over and then assemble into simple geometric shapes like a 3-D Jigsaw puzzle. Virus can use the same gene over and over instead of having more nucleic acid, which could not pack into a multiprotein coat....
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- Fall '09