Question

1. Show below is the arrangement of three genes in a heterozygous individual. All three genes have a classic dominant/recessive pattern of inheritance.  

w⁺        y⁺         c

w         y          c⁺

1. What phenotypes would you expect in the parental, single crossovers and double crossovers after a cross with a homozygous recessive individual.
2. If we know w is closer to y than it is to gene c, put the four categories above in order from highest frequency to lowest frequency.

Answer 1

A) w+y+c are having phenotype of C-

While w-y- c+ so phenotype is of w- y-

Now after crossing both parent, f1 generation is wild type heterozygous

W+WY+YC+C f1 all wild type

W+ Y+C- P1

W-Y-C+ P2

W+Y+ C+ R1. Outcome of single cross over (wild type)

W+ Y-C+ R2 outcome of single cross over (Y- mutant)

W+Y-C- R3 outcome of double cross (Y-C- mutant )

W-Y+C+ R4 outcome of double cross (W- mutant)

W-Y-C+ R5 outcome of single cross (W-Y- mutant)

W-Y-C- R6. Outcome of single cross ( all mutant)

B) (W-Y) < (W-C)

Gene order. W-Y-C

Hope it's clear..thanks