Primase adds RNA primers during DNA replication, typically 7-10 nucleotides in l

Question

Primase adds RNA primers during DNA replication, typically 7-10 nucleotides in length. Why is an RNA primer required for DNA replication?

Primases lack proofreading abilities. Does this impact the fidelity of DNA replication? Explain your answer.

Primases, RNA polymerases, and DNA polymerases all complete chain elongation in the 5' to 3' direction. What would the consequences be if polymerases instead worked in the 3' to 5' direction?

Please answer in exact detail and if you are not 100% sure, do not answer.

Explanation / Answer

RNA primer provide 3' OH group to the DNA polymerase, as the DNA pol can add new nucleotides only to an existing 3'OH group. Thus, RNA primer is added by primase enzyme wich itslef desnt need the 3'OH group for primer addition.

it does not affect the DNA fidelity because the DNA pol I,II, III all possess proofreading activity in bcaterial DNA replication where as in eukaryotes DNA pol delta and epsilon play a role in proofreading. all these enzyme possess 3'-5' exonuclease activity that helps remove incorrect bases.

If polymerases would work in 3'-5' direction, then for addition of new nucleotide every time a primer molecule will be needed. thus, fragments of DNA will be formed.

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