Question

Question 4 (1 point) Two loci are linked to each other. The Red hair locus is complete dominant in that the dominant allele (R) provides an individual with non-red hair and the recessive allele (r) provides an individual with red hair. The Freckles locus is completely dominant in that the dominant allele (F) codes for freckles and the recessive allele (f) doesn't cause freckles. You often see red hair and freckles occurring together, suggesting the two loci are linked. Provided the information below, Red hair locus phenotype Freckles locus phenotype Number of progeny from dihybrid testcross 7 Red Freckles Non-Red None 5 Red None 3 Non-Red Freckles 1 What is the distance between the red hair and freckles loci? (use 1 decimal place, be sure to include units in your answer.)

Answer 1

Non red (F) is dominant over red hair (r)

Freckles (F) is dominant over non freckles(f)

Red and Freckles (rF)  - 7

Non red and no freckles (Rf) -5

These two are parental combinations

Red and non freckles (rf) -3

Non red and freckles (RF) -1

These two are recombinant

Total number is 16

Recombination frequency between r and f gene = (3+1 / 16 ) X 100

=25% or 25 Map Unit

So distance between the red hair and freckles loci is 25 Map Unit.