Lethal allele when a Chinese hamster with white spots is crossed with another ha
ID: 210498 • Letter: L
Question
Lethal allele when a Chinese hamster with white spots is crossed with another hamster that has no spots, approximately ½ of the offspring have white spots and ½ have no spots. When two ham sters with white spots are crossed,23 of the offspring possess white spots and 1/3 has no spots. What is the genetic basis of white spotting in Chinese hamsters? Gene interaction/Epistasis In chickens, comb shape is determined by alleles at two loci (R, r and P, p). A walnut comb is produced when at least one dominant allele R is present at one locus and at least one dominant allele P is present at a second locus (genotype R_P_). A rose comb is produced when at least one dominant allele is present at the first locus and two recessive alleles are present at the second locus (genotype R_ pp). A pea comb is produced when two recessive alleles are present at the first locus and at least one dominant allele is present at the second (genotype rr P_). If two recessive aleles are present at the first and at the second locus (rr pp), a single comb is produced. Progeny with what types of combs and in what proportions will result from the following crosses? a. Rr Pp x rr pp d. Rr pp x rr PpExplanation / Answer
a)When the white spotted chinese hamster is crossed with non spotted chinese hamster the obtained offsprings are half white spotted and half non spotted.The result suggests that the white spot (Ww)is hetrozygous phenotype and dominant to non spotting chinese hamsters (ww).When the hetrozygous white spotted hamster is self crossed with obtained offsprings are 1:2:1 ratio1 WW,2 Ww and 1 ww.The phenotype with WW is missing from the progeny making it lethal allele. resulting in 2:1 genotype.The white spotting allele with honozygous allele WW are lethal and Ww recessive letghal allele.
b)Progeny of cross RrPp and rrpp consist of chicken with 4 walnut comb.4 rose comb,4 pea comb and 4single comb.
Progeny of cross RrPp and RrPp consist of chicken with 9walnut.3rose,3peas and 1 single.
Progeny of cross Rrpp and Rrpp consist of chicken with 12 rose and 4 single comb
Progeny with cross Rrpp and rrpp consist of chicken with 4 walnut,4 rose,4 pea and 4 single.
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