Question

mcgraw hill
in dna replication,
multiple choice
both strands replicate in the same direction.
each strand replicates in a different direction.
only one strand of dna is used as a template.
a single strand of dna is copied to make two single strands of dna.

Explanation:

To solve this, we recall DNA replication concepts: DNA is double - stranded, and during replication, each strand acts as a template (so option C is wrong as both strands are templates). The two strands of DNA are antiparallel (one is 5’→3’ and the other is 3’→5’). DNA polymerase can only synthesize DNA in the 5’→3’ direction. So, the leading strand (synthesized continuously) and the lagging strand (synthesized discontinuously as Okazaki fragments) are replicated in different directions relative to the replication fork movement, meaning each strand replicates in a different direction. Option A is wrong because of the antiparallel nature and polymerase directionality. Option D is wrong as a double - stranded DNA is replicated to form two double - stranded DNAs (each with one old and one new strand).

Answer:

B. each strand replicates in a different direction.