Biol202-Meiosis and Tetratypes

Biol202-Meiosis and Tetratypes - Exam #2: 10/16/2007 Review...

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Exam #2: 10/16/2007 Review Session: 7:30PM, Coker 201, 10/15/2007 Covers: DNA replication/replication bubbles (Jeff’s lecture) Recombination Linkage mapping Tetrads, chromosomes, tri-hybrid crosses tx (transcription?), translation Ordered and unordered tetrads Chromosome abnormalities H/wk #5 due THIS week Meiosis in fungal systems vs. meiosis in humans – why study them? b/c u can see the 4 products of a meiotic event in the asci 2N- 4N - - 2N and 2N ---- 1N 1N 1N and 1N Thus, we can deduce what genetic exchange happened by looking at these products (this is hard to do if the meiotic results are not easily obtained in the asci) **Tetrad Analysis** For unlinked genes, = chance of parental ditypes (ditypes b/c theres 2 different parental types in each asci) and NPD (they’re in = frequency (the source of exchange of genetic info is how they align on the metaphase plate – another source of variation b/c of the way meiosis works – theres no genetic exchange, however, where crossover would normally take place b/c there is no crossing over) Crossing-over b/w one of the genes and its centromere = TT (tetratype) (the closer the gene is to the centromere the frequency of TT decreases – the further from the gene is from the centromere the more TT you’ll have) For linked genes, no crossover = PD (y r there so few NPD for linked genes? – b/c a single crossover b/w linked genes yields a TT) A 4 strand crossover is the only… For linked genes… **Ordered Tetrads** Not only are all 4 products are in a single asci, but their order is also maintained (researched primarily in bread mold…nuro- something)
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This note was uploaded on 03/26/2008 for the course BIOL 202 taught by Professor Kieber-hogan during the Fall '08 term at UNC.

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Biol202-Meiosis and Tetratypes - Exam #2: 10/16/2007 Review...

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