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Lecture 25 - Bio 121 Lecture 25 birds and the bees and the...

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Bio 121 Lecture 25 – birds and the bees and the virus A. The virus – HIV – human immunodeficiency virus a. Casues AIDS b. Discovered in 1981 in US c. Humans were first contacted with HIV through contact with chimpanzees d. HIV is a retrovirus (fragile virus that can’t live outside a cell) e. Different virus’s e.i. DNA virus’s – double stranded e.ii. RNA virus’s – double strand/single strand e.iii. Retrovirus f. Life cycle of HIV f.i. Outer shell of envelope proteins surrounded two identical rna strands f.ii. Rna and proteins of virus are passed into the cell and enzyme reverse transcriptase turns RNA into DNA f.iii. DNA is then inserted into nucleus and become integrated in our chromosomes – called a provirus f.iv. Host enzymes do all replication, transcription, and translation to make virus parts f.v. Virus assembles and HIV protease cuts the poly proteins into functional units of correct length and virus will bud off the cell and destroy it. g. HIV attacks Helper T cells because the GP120 receptor on virus fits into helper T (CD4) receptor g.i. Cripples immune system g.ii. Antibodies are made but don’t go into nucleus g.iii. Over time [helper t cells] decreases, and [HIV] increases h.
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