What does the body build when it needs a gene?

Bodybuilding, Strength Training, and DNA

Bodybuilders work hard to get chiseled bodies, but many also have a boost from their genetics. One important gene that has been studied and proven to impact strength and muscle size is called ACTN3. ... They are necessary for power sports, like weightlifting and sprinting.

Answer and Explanation:

It is a dihybrid cross, where:

B= black (dominant)

b= brown

S= solid (dominant)

s= spotted

a) The genotype of the parents are:

homozygous black spotted= BBss ⇒ Gametes: Bs, Bs, bS, bS

homozygous brown solid= bbSS ⇒ Gametes: bs, bs, bs, bs

The F1 mice is the resultant progeny from the cross BBss x bbSS. We combine the games of the parents and all combinations are : BbSs. All F1 genotype is BbSs (heterozygous black and solid mice).

b) The testcross is carried out between F1 mice (BbSs) and brown spotted mice (bbss)

BsSs ⇒ Gametes: BS, Bs, bS, bs

bbss ⇒ Gametes: bs, bs, bs, bs

From the gametes, we obtain all the possible combinations:

BSbs = BbSs (black, solid) ⇒ ratio= 1/2 x 1/2= 1/4

Bsbs= Bbss (black, spotted) ⇒ ratio= 1/2 x 1/2= 1/4

bSbs= bbSs (brown solid) ⇒ ratio= 1/2 x 1/2= 1/4

bsbs= bbss (brown spotted) ⇒ ratio= 1/2 x 1/2= 1/4

So, we obtain 1/4 of black solid mice (BbSs), 1/4 of black spotted mice (Bbss), 1/4 of brown solid mice (bbSs) and 1/4 of brown spotted mice (bbss).