Question

DNA polymerase I is thought to add nucleotides ________.

A. to the 3′ end of the primer
B. in the place of the primer RNA after it is removed
C. to the 5′ end of the primer
D. in a 5′ to 5′ direction
E. on single-stranded templates without need for an RNA primer

Answer 1

DNA polymerase I adds nucleotides in the place of the primer RNA after it is removed, working to synthesize DNA in the 5' to 3' direction and requiring a free 3'-OH group to form a phosphodiester bond.

Step-by-step explanation:

DNA polymerase I is thought to add nucleotides in the place of the primer RNA after it is removed. DNA polymerase synthesizes DNA in the 5' to 3' direction and requires a free 3'-OH group to add nucleotides by forming a covalent phosphodiester bond. Initially, an RNA primer is synthesized by RNA primase, which doesn't require a free 3'-OH group. DNA polymerase III then extends the RNA primer by adding DNA nucleotides. Afterward, DNA polymerase I replaces the RNA primer with DNA nucleotides. This enzyme plays a crucial role during the DNA replication process, particularly on the lagging strand where it removes the RNA primers of Okazaki fragments and fills in the gaps with DNA nucleotides.