Academic Integrity: tutoring, explanations, and feedback — we don’t complete graded work or submit on a student’s behalf.

in a corn Colored kernels (C) is dominant over colorless (c) Plump kernels (S) i

ID: 61576 • Letter: I

Question

in a corn Colored kernels (C) is dominant over colorless (c) Plump kernels (S) is dominant over shrunken (s) Starchy kernels (W) is dominant over waxy (w). A trihybrid (Cc Ss Ww) plant is testcrossed and the following progeny are obtained: 2708 Colorless, plump, waxy 2538 Colored, shrunken, starchy 626 Colorless, plump, starchy 601 Colored, shrunken, waxy 116 Colorless, shrunken, starchy 113 Colored, plump, waxy 4Colored, plump, starchy 4 Colorless, shrunken, waxy Determine linkage (including map distance) for the genes and gene order for this cross. in a corn Colored kernels (C) is dominant over colorless (c) Plump kernels (S) is dominant over shrunken (s) Starchy kernels (W) is dominant over waxy (w). A trihybrid (Cc Ss Ww) plant is testcrossed and the following progeny are obtained: 2708 Colorless, plump, waxy 2538 Colored, shrunken, starchy 626 Colorless, plump, starchy 601 Colored, shrunken, waxy 116 Colorless, shrunken, starchy 113 Colored, plump, waxy 4Colored, plump, starchy 4 Colorless, shrunken, waxy Determine linkage (including map distance) for the genes and gene order for this cross. in a corn Colored kernels (C) is dominant over colorless (c) Plump kernels (S) is dominant over shrunken (s) Starchy kernels (W) is dominant over waxy (w). A trihybrid (Cc Ss Ww) plant is testcrossed and the following progeny are obtained: 2708 Colorless, plump, waxy 2538 Colored, shrunken, starchy 626 Colorless, plump, starchy 601 Colored, shrunken, waxy 116 Colorless, shrunken, starchy 113 Colored, plump, waxy 4Colored, plump, starchy 4 Colorless, shrunken, waxy Determine linkage (including map distance) for the genes and gene order for this cross.

Explanation / Answer

Trihybrid cross

S. No.

Genotype

Number

Progeny type

1

cSw

2708

parental

2

CsW

2538

parental

3

cSW

626

Single cross over between C and S

4

Csw

601

Single cross over

Between C and S

5

csW

116

Single cross over between S and W

6

CSw

113

Single cross over between S and W

7

CSW

4

Double crossover

8

csw

4

Double crossover

From the trihybrid cross, we can say that these genes are in the order of C/c, S/s and W/w.

Distance between C and S loci = (4+ 626+601 +4/ 6710)* 100 = 50   = 18.4 m.u.

The gene distance between S and W loci is = (4+116+113+4/ 6710) *100 = 3.53 m.u.

Now, the distance between C and W loci = 18.4 + 3.53 = 21.9 map units

S. No.

Genotype

Number

Progeny type

1

cSw

2708

parental

2

CsW

2538

parental

3

cSW

626

Single cross over between C and S

4

Csw

601

Single cross over

Between C and S

5

csW

116

Single cross over between S and W

6

CSw

113

Single cross over between S and W

7

CSW

4

Double crossover

8

csw

4

Double crossover