Question

There are two loci linked to 30 cM separation in an autosome of
the rat. The hairs taps are produced by the genotype
recessive kk, and a short tail by a recessive genotype ss. The
Dominant alleles produce normal hair and tail. Determine the
expected phenotypic proportions from the precursors
heterozygotes that are

a) both in cis arrangement, b) both in
trans arrangement, c) one in cis arrangement and the other in trans.

Answer 1

Answer:

a).

Both in cis arrangement; k+ s+ / k s X k+ s+ / k s

Distance between genes (mu) = % of recombination frequency

	k+ s+ 0.35	k+ s 0.15	k s+ 0.15	k s 0.35
k+ s+ 0.35	0.1225	0.0525	0.0525	0.1225
k+ s 0.15	0.0525	0.0225	0.0225	0.0525
k s+ 0.15	0.0525	0.0225	0.0225	0.0525
K s 0.35	0.1225	0.0525	0.0525	0.1225

k+ _ s+_ = 0.6225 = 62.25%

k+_ss = 0.1275 = 12.75%

kk s+_ = 0.1275 = 12.75%

kkss = 0.1225 = 12.25%

b).

Both in trans arrangement; k+ s / k s+ X k+ s / k s+

	k+ s+ 0.15	k+ s 0.35	k s+ 0.35	k s 0.15
k+ s+ 0.15	0.0225	0.0525	0.0525	0.0225
k+ s 0.35	0.0525	0.1225	0.1225	0.0525
k s+ 0.35	0.0525	0.1225	0.1225	0.0525
k s 0.15	0.0225	0.0525	0.0525	0.0225

k+ _ s+_ = 0.5225 = 52.25%

k+_ss = 0.2275 = 12.75%

kk s+_ = 0.2275 = 12.75%

kkss = 0.0225 = 2.25%

c).

one in cis arrangement and the other in trans.

k+ s+ / k s X k+ s / k s+

	k+ s+ 0.15	k+ s 0.35	k s+ 0.35	k s 0.15
k+s+ 0.35	0.0525	0.1225	0.1225	0.0525
k+s 0.15	0.0225	0.0525	0.0525	0.0225
k s+ 0.15	0.0225	0.0525	0.0525	0.0225
k s 0.35	0.0525	0.1225	0.1225	0.0525

k+ _ s+_ = 0.5525 = 55.25%

k+_ss = 0.1975 = 19.75%

kk s+_ = 0.1975 = 19.75%

kkss = 0.0525 = 5.25%