Bio97_09+L14

Bio97_09+L14 - Bio Dr Carrie Brachmann Office hours Mondays...

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©2009 C. Brachmann 1 Linked Genes and Gene Mapping I Bio Sci 97, 2009 Dr. Carrie Brachmann Office hours Mondays and Fridays 12-1:30 (10/30, 11/2, 11/6, 11/9, 11/13, 11/16) AND Weds, Dec 2 12-1:30, 3-4 4213 McGaugh Hall I will post old test questions at the end of each lecture, and some will be answered at the beginning of the next lecture. Please keep up with the reading as assigned in the syllabus and work through the problems.
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©2009 C. Brachmann 2 Genetic mapping is necessary Despite the fact that genomes are sequenced A gene’s sequence doesn’t tell its function Mutant phenotype must be mapped, ( meaning the position of the mutation causing the phenotype must be determined relative to other genes along a chromosome ) First step toward developing therapies for genetic diseases
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©2009 C. Brachmann 3 Outline Gene linkage Recombination The Genetic Map Linkage group Mapping three genes Double crossovers Three-point mapping Interference Lecture 14 Lecture 15
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©2003 C. Brachmann 4 Independent assortment: Remember… during meiosis, each chromosome segregates independently. For any two chromosomes, one-half of the meiotic products are parental and one-half are recombinant. Good Review in Gist of Genetics, Chapter 5 (Science library) Alleles: Homologous pairs of chromosomes contain the same genes but they can carry different forms of each gene. Each “form” is an allele. Mutant alleles are usually either dominant or recessive to the wild-type allele. Review slide
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©2003 C. Brachmann 5 Review of  independent  assortment for two  chromosomes A B B A a b b a b a B A A A B B a a b b AB AB ab ab Ab Ab aB aB AND AND parents haploid  gametes F1 cells  diploid Metaphase I of meiosis in germ  cells of the F1 Meiotic products of  the F1 hybrid A b a B 6 A B A b B a a b Review slide
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©2009 C. Brachmann 6 In meiosis,  alleles  of genes in different chromosomes  sort independently, but what about alleles of genes  that are in the same chromosome?   T.H. Morgan suggested that genes that are frequently  inherited together  are in the same chromosome and  thus  LINKED.  
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©2009 C. Brachmann 7 A a d d A D d D D A a a 25% 25% 25% 25% meiosis (1:1:1:1) d A D a Review of independent assortment
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©2009 C. Brachmann 8 d d D d D D 25% 25% 25% 25% meiosis (1:1:1:1) d D A r a R A r a R A r A r a R a R Add a second gene on chromosome (close to first gene): the A gene is linked to  the R gene
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©2009 C. Brachmann 9 But linkage may not always be complete, meaning the two genes may not segregate together in every meiosis The alleles of R and A segregate together The alleles of R and A DO NOT segregate together Gametes with a new combination of the alleles are called recombinant A a r R A r a R F1 hybrid Nonrecombinant (parental) meiotic products A R a r Recombinant meiotic products
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©2009 C. Brachmann 10 Terms: cis, trans,
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This note was uploaded on 02/09/2011 for the course BIO 97 taught by Professor Edinger during the Spring '10 term at UC Irvine.

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Bio97_09+L14 - Bio Dr Carrie Brachmann Office hours Mondays...

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