Question

Two different pure-breeding lines of corn were obtained with a tester that was homozygous recessive for the three genes. The parentals shriveled (sh/sh. br+/br+. f+/f+) and brown and fine (sh+/sh+. br/br. f/f) were crossed. The F1 was wildtype. The F1 was testcrossed (sh/sh. br/br. f/f) and the following F2 progeny was obtained: 3601 shriveled; 3713 brown and fine; 1021 brown; 865 fine and shriveled; 453 shriveled and brown; 333 fine; 6 wildtype; 8 shriveled, brown and fine. a. Write out the genotypes and phenotypes of the crosses. Include P, F1 and F2 generations and correct nomenclature (e.g. linked/unlinked, gene order). b. Draw a table including each of the F2 phenotypic classes and identify, for each pair of gene loci (3), the parentals and recombinants. Identify the double recombinants. c. Determine the gene order of the loci, calculate the map distances between the loci and draw a recombination map. You must show all calculations.

          Two different pure-breeding lines of corn were obtained with a tester that was homozygous recessive for the three genes. The parentals shriveled (sh/sh. br+/br+. f+/f+) and brown and fine (sh+/sh+. br/br. f/f) were crossed. The F1 was wildtype. The F1 was testcrossed (sh/sh. br/br. f/f) and the following F2 progeny was obtained: 3601 shriveled; 3713 brown and fine; 1021 brown; 865 fine and shriveled; 453 shriveled and brown; 333 fine; 6 wildtype; 8 shriveled, brown and fine.

a. Write out the genotypes and phenotypes of the crosses. Include P, F1 and F2 generations and correct nomenclature (e.g. linked/unlinked, gene order).
b. Draw a table including each of the F2 phenotypic classes and identify, for each pair of gene loci (3), the parentals and recombinants. Identify the double recombinants.
c. Determine the gene order of the loci, calculate the map distances between the loci and draw a recombination map. You must show all calculations.

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Added by John C.

Biology for AP Courses

Julianne Zedalis, John Eggebrecht

Instant Answer

Solved by Expert Supreeta N

08/21/2023

Step 1

P: - Parent 1: sh/sh . br+/br+ . f+/f+ (shriveled) - Parent 2: sh+/sh+ . br/br . f/f (brown and fine) F1: - sh/sh+ . br+/br . f+/f (wildtype) F2: - 3601 shriveled (sh/sh . br+/br . f+/f) - 3713 brown and fine (sh+/sh+ . br/br . f/f) - 1021 brown (sh+/sh+ . Show more…

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Two different pure-breeding lines of corn were obtained with a tester that was homozygous recessive for the three genes. The parentals shriveled (sh/sh. br+/br+. f+/f+) and brown and fine (sh+/sh+. br/br. f/f) were crossed. The F1 was wildtype. The F1 was testcrossed (sh/sh. br/br. f/f) and the following F2 progeny was obtained: 3601 shriveled; 3713 brown and fine; 1021 brown; 865 fine and shriveled; 453 shriveled and brown; 333 fine; 6 wildtype; 8 shriveled, brown and fine. a. Write out the genotypes and phenotypes of the crosses. Include P, F1 and F2 generations and correct nomenclature (e.g. linked/unlinked, gene order). b. Draw a table including each of the F2 phenotypic classes and identify, for each pair of gene loci (3), the parentals and recombinants. Identify the double recombinants. c. Determine the gene order of the loci, calculate the map distances between the loci and draw a recombination map. You must show all calculations.

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Transcript

00:01 Hello students, starting with the genotypes and phenotypes of the process.

00:07 So parental close that is p1a into p1b.

00:17 The p1a sh sh br plus br plus f plus f plus that is shriveled, brown and fine.

00:38 Second p1b sh plus sh plus br br f f that is brown and fine and f1 sh plus sh plus br plus br plus f plus f plus that is wild type.

01:12 In the case of test close that is f1 into tester.

01:17 So we already got the f1 genotypes, tester genotype sh sh br br f f that is shriveled, brown and fine and then f2 with the genotype so that will be we will found with the help of the table shriveled will be there, brown will be there and fine will be there.

01:54 So let us see the table here, here the genotypes will be sh sh br plus br plus f plus f plus that will be parental category.

02:09 For brown and fine sh plus sh plus br br f f again parental category.

02:18 For brown sh plus sh plus br plus br f plus f plus which is recombinant.

02:26 For fine and shriveled sh sh br br f plus f plus again recombinant.

02:39 Shriveled and brown sh sh br plus br f f again recombinant.

02:49 For fine sh plus sh plus br plus br f f again recombinant.

02:59 And wild type sh plus sh plus br plus br f plus f plus again recombinant.

03:11 And shriveled brown and fine sh sh br br f f which is parental.

03:21 So it was the b part of the question...

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