Multiple Choice
In the overview of DNA replication, what is the primary role of DNA polymerase?
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8. DNA Replication
Overview of DNA Replication
Multiple Choice
In an overview of DNA replication, new DNA strands are synthesized in which direction relative to the growing strand?
A
5′ to 3′ (nucleotides are added to the 3′ end)
B
Replication proceeds from the middle of the chromosome toward both ends without a defined 5′/3′ direction
C
3′ to 5′ (nucleotides are added to the 5′ end)
D
Both 5′ to 3′ and 3′ to 5′ on the same strand simultaneously
Verified step by step guidance1
Understand the structure of a DNA strand: DNA strands have directionality, with one end called the 5′ (five prime) end and the other called the 3′ (three prime) end, based on the carbon numbering in the sugar backbone.
Recall that DNA polymerase, the enzyme responsible for synthesizing new DNA strands, can only add nucleotides to the 3′ end of a growing strand, meaning synthesis occurs in the 5′ to 3′ direction.
Recognize that nucleotides are added as nucleoside triphosphates, which provide energy for the formation of phosphodiester bonds at the 3′ hydroxyl group of the last nucleotide in the strand.
Note that replication does not proceed from the middle of the chromosome toward both ends; instead, it starts at origins of replication and proceeds bidirectionally but always synthesizes new strands in the 5′ to 3′ direction.
Understand that although the two strands of DNA are antiparallel, the new strands are synthesized continuously on the leading strand and discontinuously on the lagging strand, but both are synthesized in the 5′ to 3′ direction relative to the new strand.
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