However in the test cross below morgan found an

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Unformatted text preview: o Mendel's results. In the example below, the test cross to a homozygous (male) tester, produce the standard 1:1 ratio typical of a monohybrid cross. In other word, the eye color ( pr) and wing shape (vg) are acting as one gene or "linked". F1 pr + vg X + pr pr vg tester vg Parentals pr pr vg vg pr + vg + 1:1 ratio March 19, 2012 BIS101001, Spring 2012--Genes and Gene Expression, R.L. Rodriguez 2012 18 Morgan's 2-factor cross: 4, not 2 class of phenotypes* For two linked genes, a 1:1 phenotypic ratio is expected from a testcross (homozygous recessive male) with F1 progeny. However, as shown in the table below, about 20% of the testcross progeny show recombinant phenotypes in addition to the parental phenotypes. The recombinant progeny produced from the test cross exhibited only one of the two mutant phenotypes. In other words, the + + linkage was broken to yield the + vg (vestigial) and the pr + phenotypes (Table 1). GENE COMBIINATIION GENE COMB NAT ON ++//prrvg ++ p v g prrvg//pr...
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