What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?
A. DNA polymerase can join new nucleotides only to the 3?3? end of a preexisting strand, and the strands are antiparallel.
B. The origins of replication occur only at the 5?5? end.
C. DNA ligase works only in the 3?3? ?? 5?5? direction.
D. Helicases and single-strand binding proteins work at the 5?5? end.
Ans: A. DNA polymerase can join new nucleotides only to the 3?3? end of a preexisting strand, and the strands are antiparallel.
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