Question

Compared to RNA elongation by RNA polymerases, DNA elongation by DNA polymerase requires an additional reaction component. Which is appropriate for fulfillment of this requirement?

Select one:

a. a primase is needed for the biological DNA replication.

b. a short DNA primer is necessary for PCR.

c. a host tRNA is used for the synthesis of DNA by viral reverse transcriptase.

d. All of these

e. None of these

Answer 1

All of these

DNA polymerase is the enzyme which is responsible for the elongation of DNA during DNA replication. It cannot initiate DNA synthesis on its own and requires a free hydroxyl group. This free hydroxyl group is provided by an RNA primer which is synthesized by primase enzyme at 3' end of parental DNA molecule. The primer provides a frre hydroxyl group at 3' end.

Not only inside living system, but DNA replication in vitro also requires a primer which provides a free hydroxyl group. During PCR primer pair is added during the type of annealing and primer binds to 3' end of single stranded template DNA.

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