DNA replication always proceeds in only one direction because the ________ of the incoming nucleotide is attached to the free ________ of the growing DNA strand.
A) 5ʹ-phosphate / 3ʹ-hydroxyl
B) 3ʹ-phosphate / 5ʹ-hydroxyl
C) 5ʹ-deoxyribose / 3ʹ-base
D) 3ʹ-base / 5ʹ-deoxyribose

Question

Quizplus · Accepted Answer

DNA replication proceeds in only one direction because the 5ʹ-phosphate group of the incoming nucleotide is covalently attached to the 3ʹ-hydroxyl group of the growing DNA strand. This forms a phosphodiester bond and results in a linear, unbranched chain with a free 5ʹ end and a free 3ʹ end. The direction of replication is referred to as the 5ʹ → 3ʹ direction, or the direction in which the new DNA strand is elongating.

DNA Replication Always Proceeds in Only One Direction Because the ________