Question

What is the effect of increased expression of X-linked genes in males via the dosage compensation complex (DCC)?

1) It leads to overexpression of X-linked genes in males
2) It leads to underexpression of X-linked genes in males
3) It has no effect on the expression of X-linked genes in males
4) It leads to equal expression of X-linked genes in males and females

Answer 1

The effect of increased expression of X-linked genes in males via the dosage compensation complex is to equalize the expression of X-linked genes between males and females, despite differences in X chromosome number.

Step-by-step explanation:

4) It leads to equal expression of X-linked genes in males and females.

The dosage compensation complex (DCC) is a molecular mechanism that ensures equal expression of X-linked genes in males and females despite the discrepancy in the number of X chromosomes. In species like Drosophila, a protein known as CLAMP binds to specific nucleotide repeats on the X chromosome and helps to increase gene expression in males, leveling the expression to that of females.

Similarly, in humans and other mammals, a phenomenon known as X inactivation occurs, where one of the two X chromosomes in females condenses into a Barr body, silencing most of its genes. Consequently, both males with one active X chromosome and females with one active X chromosome express X-linked genes at comparable levels, ensuring functional equilibrium between the sexes.