DNA polymerase requires a primer to initiate DNA replication. In a PCR reaction,
ID: 51584 • Letter: D
Question
DNA polymerase requires a primer to initiate DNA replication. In a PCR reaction, DNA primers are added to the reaction. In E.coli, how are primers provided?
In vivo DNA replication does not require a primer.
DNA primers are synthesized by DNA polymerase I.
RNA primers are synthesized by DNA primase.
E.coli DNA polymerase III has a primer embedded inside the enzyme.
A.In vivo DNA replication does not require a primer.
B.DNA primers are synthesized by DNA polymerase I.
C.RNA primers are synthesized by DNA primase.
D.E.coli DNA polymerase III has a primer embedded inside the enzyme.
Explanation / Answer
The answer is C. RNA primers are synthesized by DNA primase.
DNA polymerases require 3' -OH group to extend the polynucleotide. However to create a 3'-OH group a DNA primase intially adds a short RNA which is then extended by the DNA polymerase. Later this RNA is removed by an RNAse and that short gap is filled by a low processivity DNA polymerase.
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