Question

The cross EEFF X eeff is made, and a testcross is then performed with the f1 individuals. The testcross yield the following proportion of offspring.

2/6 EeFf,

1/6 Eeff,

1/6 eeFf,

2/6 eeff

a) if the two genes are unliked, them what should the proportion of offspring be?

b) Do the testcross results suggestion suggestion that the gene are linked or unlinked?

c) if the two genes are linked, then how far apart are they?

Answer 1

Answer.

EEFF x EEFF -------parents

EeFf -----------F1

EeFf x eeff-------test cross.

a) if the genes are unlinked, the proportion of offspring is as follows.

	ef
EF	EeFf (1/4)
Ef	Eeff (1/4)
eF	eeFf(1/4)
ef	eeff(1/4)

b&c).

Parental phenotypes= EeFf & eeff = 2+2=4

Recombinant phenotypes= Eeff & eeFf =1+1=2

Recombination frequency = ( number of recombinants/ total progeny) *100

= (2/6)*100= 33.33%

Recombination frequency ( %)= Distance between the genes (map units).

Therefore, the two genes are 33.33 map units far away.