Question

Answer is A) but don't understand

19. Which of the following statements regarding dosage compensation is TRUE? i) In Drosophila gene expression is increased from a single X chromosome. ii) In Drosophila gene expression is increased from a pair of X chromosomes. iii) In C. elegans gene expression is reduced from a pair of X chromosomes. iv) In C. elegans gene expression is increased from a pair of X chromosomes. A) i and iii B) ii and iv C) All of the above are false D) All of the above are true

Answer 1

dosage compensation is the mechanism to have an equal expression of genes on the X chromosome in both male and females,

in Drosophila, females have 2 X chromosomes and males have one X chromosome and one Y chromosome, in Drosophila males as a part of dosage compensation the expression of genes on the X chromosome is doubled.

In C.elegans males have only one X chromosome and hermaphrodites have 2 X chromosomes, in hermaphrodites expression of genes on the X chromosome is reduced to half, so that males and hermaphrodites have the same level of expression of genes on the X chromosome.

so the answers are i) Drosophila gene expression is increased from a single X chromosome.

iii) C.elegans gene expression is reduced from a pair of X chromosomes.