Hi guys, i need help with two questions:
1. In horses, black coat color is coded by the dominant allele (B), and chestnut coat color is coded by the recessive allele (b). Trotting gait is due to dominant gene (T), pacing gait to the recessive allele (t). If a homozygous black trotter is crossed to a chestnut pacer,
a. what will be the appearance of the F1 and F2 generations?
b. which phenotype will be the most common in the F2 generation?
c. which genotype will be the most common in the F2 generation?
d. which of the potential offspring will be certain to breed true?
2. A breeder of cattle has a herd of white cows and a roan bull. Hair color in the breed is controlled by an incompletely dominant gene. The two homozygous forms are either red or white, and the heterozygous is roan.
a. What color of calves are expected and in what proportions?
b. Outline a procedure to develop an all-red herd.
Please help me and explain this!!!
2 questions with geno/phenotype?
Yes, you do. Take the question one step at a time. In #1
Homozygous Black trotter = BBTT
Chestnut pacer = bbtt
This is a typical dihybrid cross. In the Fl generation all offspring must get a B and a T from one parent and a b and a t from the other parent. So all offspring are BbTt. In appearance or the phenotype, the offspring will be Black trotters. The F2 generation with be a cross of the F1 offspring or
BbTt to a BbTt which will give you the characteristic 9:3:3:1 ratio. You can find this in you book.
For question #2.
You have a white calf and a roan bull. Homozygous are red or white while heretozygous is roan. So first define you symbols.
white calf = WW
roan = Ww
red = ww (both little letters)
Therefore cross WW with Ww. This should tell you the phenotypes of all the offspring. remember WW = white color and Ww = roan.
Now how can you get all red. Once you get your offspring from the cross with the white and roan, you should be able to get a red herd. you will need to cross your heterozygotes.
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