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DNA Replication: Leading Strand

APBIO-13V45E

A section of DNA appears as shown below. When replication occurs, this molecule is being unzipped in from left to right.

Which of the following will be the leading strand, and why?

Created for Albert.io. Copyright 2016. All rights reserved.

A

The top strand, because DNA polymerase “reads” the template strand in a 5’ $\longrightarrow$ 3' direction, forming the new strand in a 3' $\longrightarrow$ 5’ direction.

B

The bottom strand, because DNA polymerase “reads” the template strand in a 3' $\longrightarrow$ 5' direction, making the new strand in segments running 3’ $\longrightarrow$ 5’.

C

The top strand, because DNA polymerase replicates the template strand in a continuous 5' $\longrightarrow$ 3' direction.

D

The bottom strand, because the leading strand is always replicated in a 5’ $\longrightarrow$ 3’ direction, and the lagging strand is always replicated 3’ $\longrightarrow$ 5’.