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 DNA Repair Q?  

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Q.- In the misincorporation of bases during DNA Replication, Which proofreading activity is critical in determining the accuracy of Nuclear DNA Replication and thus the base substitution mutation rate in human chromosomes?

a) 3' to 5' polymerase activity of DNA Polymerase Delta
b) 3' to 5' Exonuclease activity of DNA Polymerase Gamma
c) 3' to 5' exonuclease activity of DNA Polymerase Delta.
d) Primase activity of DNA Polymerase Alpha
e) 5' to 3' Polymerase activity of DNA Polymerase III

Let's try this one :wink:




none of these look correct to me. Shouldn't it be 3' to 5" exonuclease of DNA poly Beta?


C) 3' to 5' exonuclease activity of DNA Polymerase Delta.


Suvi, in prokaryotes, its DNA pol 3, and these are equivalent to Polymerase Delta in the humans (source Kaplan biochem) :o)


Kaplan webprep and FA says beta/epsilon involved in repair, delta involved in leading strand poly :roll: !!! confused!!!


Sorry got says epsilon/beta in repair; that (probably) doesn't mean proofreading


Good guys,

Answer: c)

The 3' to 5' Exonuclease activity of DNA polymerase Delta represents the Proofreading activity of an enzyme required for the Replication of Human chromosomal DNA.

DNA Pol Gamma (mitochondrial) & DNA pol III (prokaryotic) do not participate in this process, short RNA primers are replaced with DNA during Replication, and new DNA strands are always synthesized in the 5' to 3' direction.

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