Introduction to Genetic Analysis 123

Introduction to Genetic Analysis 123 - 44200_04_p115-150...

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122 Chapter 4 Eukaryote Chromosome Mapping by Recombination Input Tester P Output Meiotic diploid (F 1 ) A/a . B/b A . B a . b n 2n A/A . B/B a/a . b/b . Meiosis . . . . Meiosis Fertilization Parental-type gamete Parental-type gamete Recombinant gamete Recombinant gamete Parental type + + + + Progeny (2 ) Parental type Recombinant Recombinant ± . . . . . . . . Figure 4-7 Detection of recombination in diploid organisms. Recombinant products of a diploid meiosis are most readily detected in a cross of a heterozygote and a recessive tester. Note that Figure 4-6 is repeated as part of this diagram. in Figure 4-8. Let’s reconstruct a standard Mendelian analysis to illustrate how recombinants are produced: P A / A ; B / B ± a / a ; b / b Gametes A ; Ba ; b F 1 A / a ; B / b Testcross A / a ; B / b ± a / a ; b / b F 1 dihybrid Tester Progeny A / a ; B / b a / a ; b / b A / a ; b / b recombinant a / a ; B / b recombinant The last two genotypes must be recombinant because they were formed from gametes of the dihybrid (output) that differed from the gametes that formed the F 1 (input). Note that the frequency of recombinants from
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.

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