14 15 9 10 11 12 13 13. This pedigree shows inheritance of black and orange coat
ID: 216743 • Letter: 1
Question
14 15 9 10 11 12 13 13. This pedigree shows inheritance of black and orange coat coloring in domestic cats controlled by a single gene on the X chromosome with two alleles: Xo and X"· X"X" females and and XoY males are orange; XbX" females and Xy males are black. XoXo females are calico with patches of black and orange fur. The gel image shows alleles of a microsatellite marker locus on the X chromosome-gel lanes are aligned with the corresponding individual in the pedigree above. a. Why do males always have one band while females sometimes have one and sometimes two? b. Which microsatellite marker is associated with orange coat color? . Which individuals have progeny that provide information about recombination frequency? d. Assuming that the allele coupled to X" is the same in #14 and 15, what recombination frequency between the coat color gene and the marker is indicated by these data?Explanation / Answer
a) the gene and the associated marker are on the X chromosome. Males have only 1 copy of X chromosome, as the other is Y, while females have 2 copies of X. Hence males will always have any 1 of the 2 alleles at a time (hemizygous) but females may get 2 same alleles(homozygous) -corresponding to 1 band- or may get 2 different alleles (heterozygous) - corresponding to 2 bands - at a time.
b) microsatellite markers A is associated with orange colour. This is because most of the orange coloured individuals have bands corresponding to marker A.
c)#2 and #16. They are recombinant progenies as inspite having an orange coat, they have B microsatellite markers instead of A.
d) there are only 2 recombinant progenies as mentioned in (b).
Recombinant frequency = number of recombinants/ total number of progenies
= 1/6
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