The -hydroxyl group used to initiate DNA synthesis comes from
A) a RNA primer.
B) the magnesium ion.
C) uracils, always.
D) amino acids, always.

Question

The  -hydroxyl group used to initiate DNA synthesis comes from
A) a RNA primer. 
B) the magnesium ion. 
C) uracils, always. 
D) amino acids, always.

Quizplus · Accepted Answer

The 3'-hydroxyl group used to initiate DNA synthesis comes from the RNA primer. This is because DNA polymerase can only add nucleotides to a pre-existing 3'-OH group, and the RNA primer provides this starting point for elongation of the new DNA strand.

Therefore, Option A is the best choice as it correctly explains the origin of the 3'-hydroxyl group used to initiate DNA synthesis. The other options are incorrect as magnesium ions and uracils do not directly contribute the 3'-hydroxyl group required for DNA synthesis initiation, and amino acids are not involved in the early stages of DNA synthesis.

The -Hydroxyl Group Used to Initiate DNA Synthesis Comes