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Biology HLTheme D: Continuity and change (HL)
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Outline the role of the enzyme DNA helicase and the enzyme DNA polymerase during DNA replication.
States that DNA helicase unwinds the double helix and separates the two strands by breaking the hydrogen bonds between complementary base pairs.
States that DNA polymerase synthesizes a new complementary strand by adding free nucleotides that pair with the exposed bases on the template strand.
States that DNA polymerase can only add nucleotides in the 5′ to 3′ direction, which is why replication proceeds continuously on one strand and discontinuously (in fragments) on the other.
Check your reasoning:The 5′-to-3′ restriction on DNA polymerase is the key reason one new strand (leading) is synthesized continuously and the other (lagging) is synthesized as Okazaki fragments.
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