For the DNA strands of a circular chromosome, unwinding creates torsional stress that accumulates as the unwound region gets larger and as DNA replication progresses. The accumulating stress could break the molecule at random locations, potentially leading to a breakdown of DNA replication. How does the cell prevent this stress?

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Through the action of DNA polymerase I, which unwinds the helix and prevents it from re-forming with RNA primers still incorporated into the DNA strand

Through the action of single-stranded binding proteins (SSBs), which stabilize the DNA prior to replication, preventing it from supercoiling or reannealing

Through the action of topoisomerases, which catalyze a controlled cleavage and rejoining of DNA, thus enabling over-twisted strands to unwind

Through the action of helicases, which unwind the helix by breaking and re-forming hydrogen bonds

 

asked May 13, 2013 in Genetics by GeneX ~Top Expert~ (7,947 points)
    

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Through the action of topoisomerases, which catalyze a controlled cleavage and rejoining of DNA, thus enabling over-twisted strands to unwind

 

answered May 13, 2013 by GeneX ~Top Expert~ (7,947 points)

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