co-dominance and incomplete dominance questions?

Crimson Te

1. when shorthorn red cattle are bred to shorthorn white cattle, they produce roan (red and white hairs interspersed) offspring. What type of inheritance is this?
(a) If two roan shorthorns are crossed, what is the probability of red, white, and roan colors in their offspring?
2. In the petunia, a pure breeding red flower is crossed witha white one to produce pink offspring. What form of inheritance is this?
(a) Show the genotypes of the parents and the F1 generation of a cross between a red and white petunia.
(b) What would be the anticipated offspring if the F1 plant from (a) above were testcrossed to the red parent?
(c) What would be the anticipated offspring of the F1 plant from (a) above were testcrossed to the white parent?
3. in andalusian fowl, F^B is the gene for black plumage. F^b is the gene for white plumage. These genes show incomplete dominance. The heterozygous condition results in blue plumage. List the genotypic and phenotypic ratios expected from the crosses:
(a) black X blue
(b) blue X blue
(c) blue X white
4. Two carnations (flowers), a red one and a white one, are crossed and the F2 offspring have three different genotypes. If this gene shows incomplete dominance, what is the color of the heterozygous plants?
5. In guinea pigs, coat color is determined by at least three alleles. Yellow is homozygous dominant, two other colors are also possible; white and ecru (creamcolored). Which is the homozygous recessive color?
Determine the expected genotype and phenotype ratio of the F1 generation which would result from:
(a) a cross between two cream colored guniea pigs
(b) a yellow coated and cream coated animal breeding.
6. On a fox ranch, a mutation arose that gave a platinum coat color that was very popular for fur buyers. The breeders couldnt breed a pure strain of platnium foxes; every time they bred two platnium foxes together, there were some normal foxes in the progeny. For example, in repeated matings of the same platinum foxes, 82 platinums and 38 normal offspring were produced. state a concise genetic hypothesis to account for these results.
7. in dogs, gum coloration is co-dominant, with black exerting dominance over pink. You have a lovely spotted gummmed LAbrador retreiever who has just had 8 pups. Four of the pups have spotted like your dog, and 4 have pink gums. What is the likely phenotype of the sneaky neighbor dog?

Thank you so much!

Answer
1. codominance - F1 hybrids show traits of both parents (ie red and white hairs interspersed)
(a) let IrIr = red, IwIw = white & IrIw=roan. IrIw x IrIw = IrIr, IrIw, IrIw & IwIw. So 1 red (25%), 2 roan (50%) & 1 white (25%) in F1
2. Incomplete - F1 hybrids don't resemble either parent
(a) Let AA = red, aa=white, Aa = pink. Parents: AA x aa = all Aa (pink) F1.
(b) So Aa x AA = AA, AA, Aa & Aa (50% red AA, 50% pink Aa).
(c) Aa x aa = Aa, Aa, aa & aa (50% pink Aa & 50% white aa).
3. (a) black X blue is F^BF^B x F^BF^b = 50% black F^BF^B & 50% blue F^BF^b
(b) blue X blue is F^BF^b x F^BF^b = 25% black F^BF^B, 50% blue F^BF^b & 25% white F^bF^b
(c) blue X white = F^BF^b x F^bF^b = 50% blue F^BF^b & 50% white F^bF^b
4. Aa & pink.
5. In guinea pigs, coat color is determined by at least three alleles. Yellow is homozygous dominant, two other colors are also possible; white and ecru (creamcolored). Which is the homozygous recessive color? Let Yellow = YY, white will be the homozygous recessive yy & ecru Yy.
Determine the expected genotype and phenotype ratio of the F1 generation which would result from:
(a) a cross between two cream colored guniea pigs - 25% yellow YY, 50% cream Yy & 25% white yy
(b) a yellow coated and cream coated animal breeding = 50% yellow YY & 50% cream Yy
6. On a fox ranch, a mutation arose that gave a platinum coat color that was very popular for fur buyers. The breeders couldnt breed a pure strain of platnium foxes; every time they bred two platnium foxes together, there were some normal foxes in the progeny. For example, in repeated matings of the same platinum foxes, 82 platinums and 38 normal offspring were produced. state a concise genetic hypothesis to account for these results. = platinum is a heterozygous genotype
7. in dogs, gum coloration is co-dominant, with black exerting dominance over pink. You have a lovely spotted gummmed LAbrador retreiever who has just had 8 pups. Four of the pups have spotted like your dog, and 4 have pink gums. What is the likely phenotype of the sneaky neighbor dog? pink gums

will my baby have red hair ?

Charisma

So the father of my baby is irish and he has flaming red hair
his mother and sister have red hair
and his dads beard grows in red

I have dark brown hair and am native american and white

will my child come out with red hair

Answer
Hair color is not a trait carried on one gene (as used to be suspected), so it's difficult to say. If anyone in your family has or had red hair, there is a possibility that you carry the "traits" for red hair, but in general, brown/black hair is dominant and even if your child is born with light hair, odds are it will darken up.

IF hair color was selected by one gene, the odds would look like this: (B=dominant (brown); b=recessive (red))

The dad is obviously "bb" because if he had a "B" gene, his hair would be brown.

Your hair IS brown so you are either "BB" or "Bb." If you are "BB" you cannot have a red-haired child because you cannot pass on a "b" gene. However, since your child MUST inherit one gene from you and one from the father, the child MUST be "Bb," therefore, your CHILD might have a red-haired child with a man who is "bb" or "Bb." (This accounts for traits that "jump" generations.)

You may also be "Bb" in which case you have brown hair but CAN have a red-haired child IF the child gets your "b" gene, since the child has to inherit a "b" gene from the red-haired father.

Hair color isn't as easy as all this though, because not only do several genes influence it, hair color is not strictly dominant/recessive. That's why we get so many colors in-between. There's a lot of co-dominance going on.

Congratulations, and I hope you have a healthy and happy baby, regardless of the color of his/her hair!

Powered by Yahoo! Answers

Title Post: co-dominance and incomplete dominance questions?
Rating: 92% based on 976 ratings. 5 user reviews.
Author: Yukie

Thanks For Coming To My Blog