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

Palomino horses have a golden yellow coat, chestnut horses have a brown coat, an

ID: 162244 • Letter: P

Question

Palomino horses have a golden yellow coat, chestnut horses have a brown coat, and cremello horses have a coat that is almost white. A series of crosses between the three different types of horses produced the following offspring: Cross Offspring palomino times palomino 13 palomino, 6 chestnut, 5 cremello chestnut times chestnut 16 chestnut cremello times cremello 13 cremello palomino times chestnut 8 palomino, 9 chestnut palomino times cremello 11 palomino, 11 cremello chestnut times cremello 23 palomino a. Explain the inheritance of the palomino, chestnut, and cremello phenotypes in horses. b. Assign symbols for the alleles that determine these phenotypes, and list the genotypes of all parents and offspring given in the preceding table.

Explanation / Answer

a). The given results indicate that the cremello and chestnut are homozygous traits. Palomino is a heterozygous trait as it produces offspring in 2:1:1 ration when palominos are self-crossed. The alleles are incompletely dominant because the Palomino phenotype resulted from chestnuts crossed with cremellos.

b). Assume the genes coding for chestnut is CB, genes coding for cremello is CW and the gene coding for palomino is CBCW.

Given that,

palomino X palomino = 13 palomino, 6 chestnut 5 cremello

CBCW X CBCW = CBCW CBCB CWCW

chestnut X chestnut = 16 chestnut

CBCB X CBCB = CBCB

cremello X cremello = 13 cremello

CWCW x cwcw = cwcw

palomino X chestnut = 8 palomino, 9 chestnut

CBCW X CBCB = CBCW CBCB

palomino X cremello = 11 palomino, 11 cremello

CBCW X CWCW = CBCW CWCW

chestnut X cremello = 23 palomino

CBCB X CWCW = CBCW