L41 BIOL 2970 Lecture Notes - Lecture 41: Lysine, Arginine, Familial Mediterranean Fever
17 Dec 2017
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Find evidence of natural selection in evolution of genes and proteins. Silent (=synonymous) substitutions are assumed to be mostly neutral alleles. Replacement (=nonsynonymous) substitutions -- mixture of deleterious, neutral, and beneficial alleles. Hiv retrovirus -- v3 region of envelope gene is highly variable -- co-receptor usage, cell tropism, Nsi-si in tissue culture, target of immune system. Genome of retrovirus -- encodes reverse transcriptase, proteins on capsid, single-stranded. Rna that will be reverse transcribed into double stranded, envelope protein on outer surface of virus (purple) Phospholipid bilayer is budded off from the previous infected host. Envelope protein recognizes receptors on surface of host cell, the fuses with membrane of host cell, inserting contents into cytoplasm of the host. After insertion, uncoated and reverse transcribed, producing a double-stranded. Dna -- integrated into host nucleus as provirus. Host divides indefinitely and replicates virus with it -- produces rna copies of the provirus, serving as mrna to synthesize viral proteins and new viral genomes.
