Anonymous asked in Science & MathematicsBiology · 10 months ago

Why would 3' to 5' polymerase activity not allow for proofreading?

I understand why polymerization cannot occur in a 3' to 5' direction, but I do not understand what about this specifically makes proofreading possible. 

2 Answers

  • 10 months ago

    I’ll be honest and say i’m not 100% on this. But it sounds as though it could be something to do with the direction of replication with respect to the replication fork. If the polymerase is working in the opposite direction to form okazaki fragments, perhaps the proofreading proteins are unable to bind as they normally would in 5’ to 3’ replication. Food for thought. 

  • 10 months ago

    Those are all "we don't find those in nature" situations.

    Your teacher probably wants you to think about

    o the action(s) being performed

    o where the energy is coming from

    o the chemical bonds being broken and made

    o are there steric hindrances?

    Yeah, I'm still going with "we don't find those in nature."  You can imagine a different set of DNA polymerase enzymes that would work the other direction.  You can imagine a primerless DNA polymerase.  For whatever reason(s) these things didn't evolve and stick around.

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