Question

UPDATED: Which of the following summarizes expression of the lac genes in this partical diploid: I⁺ P+ Oc Z^- Y+ / I^- P+ O+ Z+ Y^- ?

The Minus (-) are on the first Z and the second Y. The Plus (+) are on the first I, P and Y and on the second P,O and Z. and the c is on the first O.

A) Both permease and beta-galactosidase are made both in the presence of and in the absence of lactose.

B) Permease is made both in the presence of and in the absence of lactose; beta-galactosidase is only made when lactose is present.

C) Both permease and beta-galactosidase are made only when lactose is present.

D) Beta-galactosidase is made both in the presence of and in the absence of lactose; permease is only made when lactose is present.

Answer 1

The answer is - B) permease is made both in presence of and in absence of lactose; beta galactosidase is only made when lactose is present.

In diploid genotype left side has Oc mutation so gene will give constitutive expression. So permease will form constitutively.

But the right side has I^- so faulty repressor will produce so it cannot bind to the operator. But left side will produce active repressor that will bind to operator in the right side in absence of lactose.

So then the gene will not express.