There are 2 parts to this question an amateur horse breeder has acquired four ne
ID: 4000 • Letter: T
Question
There are 2 parts to this questionan amateur horse breeder has acquired four new bay-colouredmares (female horses) with uncertain pedigree. What are thepossible genotypes of the mares purchased?
If asked for your advice, how would you suggest the breeder goabout determining the genotype of these mares?
an amateur horse breeder has acquired four new bay-colouredmares (female horses) with uncertain pedigree. What are thepossible genotypes of the mares purchased?
If asked for your advice, how would you suggest the breeder goabout determining the genotype of these mares?
Explanation / Answer
This is a complicated problem but assuming the genotype they wantis of the color of the mares Because you don't know if their bay color is a homozygous conditionor the result of a heterozygous state you could mate them with ahorse whose color is known to be caused by being homozygousrecessive (assuming that there is a recessive allele forcolor and all colors are not caused by codominance). You would have to mate each mare more than once in order to producemultiple offspring. Assuming the Bay color is caused by having at least onedominant allele for "Bay" Possible Result 1: One of the mare is bay colored becausethey are homozygous dominant for an allele causing the baycolor. All of the offspring will inherit the dominant allelefrom their mother and should be bay colored. Possible Result 2: The mare is heterozygous. Half of herfoals should be bay and the other half should be the colordetermined by her recessive allele. Assuming this is a simple example not including codominanceor intermediate colors the possible genotypes would most likely beBb (Where B=Bay and b=a recessive color, perhaps white) orBB. If the Bay color is being caused by the mare being homozygousrecessive: then mating the mare with a homozygous malewould cause all of the offspring to be the color of their fatherand none to be the color of their mother. Then the mare wouldbe bb (b=bay) If the Bay color is being caused by co-dominance. Inthis situation none of the offspring should be the color of theirmother. Half should be one new color and the other halfshould be a different new color. This is assuming that therestill is the existance of a recessive homozygous state which youwould want to have in the father. In that situation the marecould be for example LW where L=black and W=White. I don't know if you've covered codominance or the other situationin which if a dominant allele is present and a recessive allele ispresent then the product of the dominant allele isn't enough tocause full coloration and so you can get an intermediate colorbetween the dominant and resessive ones. If you're confused let me know and I'll see what I can do
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