How does replacement of thymine with uracil in messenger RNA help in the process of protein synthesis?
A)Allowing messenger RNA to leave the nucleus
B)Ensuring only the "antisense" strand of DNA is transcribed
C)Determining the placement of the "start" signal for translation
D)Promoting posttranslational modification for conversion to an active protein

Question

Quizplus · Accepted Answer

RNA does not contain the pyrimidine base thymine. The base uracil is used in place of thymine because it is a pyrimidine base with a structure that does not contain the methyl group (CH3) that thymine has. This difference between thymine and uracil is important because molecules in the nucleus that contain a methyl group remain trapped inside the nucleus. Because the remaining phases of protein synthesis occur outside the nucleus, the newly transcribed RNA must be able to exit the nucleus.

How Does Replacement of Thymine with Uracil in Messenger RNA