04BIS10110152013RecombinLect4

This is typically done using a test cross to an f1

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Unformatted text preview: rgan or 1 cM) ­ (Remember, 1 crossover produces 2 crossover gametes so recombinant (Remember, progeny must be added together when calculating % recombination as shown below) In Morgan’’s 2-factor cross, the genetic distance between s shown the pr and vg loci can be determined by calculating the frequency of pr vg recombinant progeny. recombinant 270 + 270 Total Recombinant Progeny Total Progeny X 100 5849 BIS101­001, Spring 2013—Genes and Gene Expression, R.L. Rodriguez ©2013 BIS101­001, Spring 2013—Genes and Gene Expression, R.L. Rodriguez X 100 = 9.2% 26 Constructing Genetic Maps ­ A genetic map is a genetic means of displaying the number of genes, their number order along the order chromosome and their relative distances from relative each other. This is typically done using a test cross to an F1 test individual carrying different alleles (heterozygous) for at least two genes or at two loci. BIS101­001, Spring 2013—Genes and Gene Expression, R.L. Rodriguez ©2013 BIS101­001, Spring 2013—Genes and Gene Expression, R.L. Rodriguez 27 3 Approaches to Constructing Genetic Maps ­ ­ ­ Approach 1. Determining gene order by performing multiple, Determining two factor crosses using overlapping loci. Gene order will be revealed by consistent map distances. revealed Approach 2. Perform a 3-factor test cross (F1 x tester) and determine genetic distances first. As above, gene order will be revealed by consistent map distances between the three loci. This approach can be performed without rare double crossover progeny. Approach 3. Perform a 3-factor cross (F1 x tester) and determine the gene order first. This is done by comparing parental phenotypes to double crossover phenotypes. From the gene order, recombinant progeny produced by recombination between loci can be calculated and these calculations will take into account double crossover progeny. If double crossover progeny are not accounted for, the map distances will not add up properly. distances BIS101­001, Spring 2013—Genes and Gene Expression, R.L. Rodriguez ...
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This note was uploaded on 02/12/2014 for the course BIS 101 taught by Professor Simonchan during the Spring '08 term at UC Davis.

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