試題詳解

39. In humans, the phenylalanine hydroxylase gene is 90,000 bases (90 kb) long, yet the mRNA is only 2,400 bases (2.4 kb). What explains this difference?
(A) RNA editing
(B) Code for poly A tail that is removed in mRNA
(C) Loss of stability without a 5’ cap
(D) Removal of exons in the final mRNA
(E) Presence of introns in DNA