A new DNA strand elongates only in the 5' to 3' direction because
A) DNA polymerase begins adding nucleotides at the 5' end of the template.
B) Okazaki fragments prevent elongation in the 3' to 5' direction.
C) the polarity of the DNA molecule prevents addition of nucleotides at the 3' end.
D) replication must progress toward the replication fork.
E) DNA polymerase can only add nucleotides to the free 3' end.

Question

Quizplus · Accepted Answer

DNA polymerase can only add nucleotides to the free 3' end because it requires a free 3' hydroxyl group to form a phosphodiester bond between the new nucleotide and the previous one. This allows for the new strand to elongate in the 5' to 3' direction only, as nucleotides are added to the 3' end of the growing strand.

A New DNA Strand Elongates Only in the 5' to 3