CAIE A Level Biology 9700 · Nucleic acids and protein synthesis
In a replication fork, parental strand X runs 5' to 3' from left to right; parental strand Y runs 3' to 5'. New strands are synthesized using free nucleotides. One new strand is formed as a continuous length; the other is formed from short fragments.
Outline the process of semi-conservative DNA replication, with reference to the roles of DNA polymerase and DNA ligase, and explain why the leading and lagging strands are synthesized differently.
7 marks, so the mark scheme is looking for about 7 separate creditworthy points. Making the same point twice in different words earns it once.
Outline means: Give the main points briefly. Less detail than describe, but every key step has to be there. One short line per step, in order. The marks are for coverage, not depth.
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