name 32 When a cross produces offspring of 3 different categories, in a phenotyp
ID: 199972 • Letter: N
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name 32 When a cross produces offspring of 3 different categories, in a phenotypic ratio of 94 3, this means that 33. Smurts are imaginary creatures who are normally blue (B), fuzzy (F), and industrious() Triple heterozygote Smurfs mated wth triple homozygote white, bald, lazy Smurfs. They had many offspring Phenotype Genotype Number Bb, F, li 1407 Normal White Bald Lazy white, bald white, lazy bald, lazy white, bald, lazy Bb, ff 19 Bb F4 bb, Fr # 121 bb. ff, 403 Total: 1000 Map these three genes 34 Book problem 4.13, pay attenton to the colors shown in the book: the symbols are not just filled in Write your genotypes on/around the pedigree. Il 12 Chapter 4 Homework ProblemsExplanation / Answer
Question 32.
Answer. The phenotypic ratio 9:3:4 indicates that the given cross is an example of "Recessive epistasis" that is Homozyous recessive genotype at one locus masks expression at second locus and in other words both functional genes are required to form the final product.
Epistasis is a phenomenon of non-allelic gene interaction where one gene at a locus masks the expression of the other gene at a different locus and thereby changing the typical mendelian F2 dihybrid cross phenotypic ratio from 9:3:3:1 to 9:3:4 or 9:7 or 12:3:1 or 15:1 etc.
Question 33.
Answer.
Where SCO = Single cross over
DCO = Double cross over.
As by looking at the parental and DCO it is clear that the gene order is "BIF" [ Note the middle alleles moves during crossong over]. Just look at the parental genotype and DCO and try to compare them , you will find that it is the allele "I" which has moved from it's location.
Distance betwwen B and I = No of SCO + No. of DCO / Total X 100%
= 71+ 69+ 4+6/1000 X 100
= 15 cM
Distance between I and F = 21+19+ 4+6/ 1000 X 100
= 5 cM
Therefore linkage map is
B--------------------------15cM--------------------------I-------------5cM----------------F.
Phenotype Genotype Number Type of crossover Normal BFL 407 Parental White bFI 71 SCO btw B and I Bald BfI 19 SCO btw I and F Lazy BFi 4 DCO white, bald bfI 6 DCO White, Lazy bFi 21 SCO btw I and F Bald, Lazy Bfi 69 SCO btw B and I White, Bald, Lazy bfi 403 Parental Total 1000Related Questions
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