Describe the function of enzymes DNA helicase and DNA polymerase during DNA replication (2 marks)
DNA replication occurs in two phases: DNA separation (DNA helicase) and DNA transcription (DNA polymerase)
Enzyme Function:
1. DNA helicase – (unwinding DNA and) breaking hydrogen bonds between DNA strands (1 mark)
2. DNA polymerase – joins (adjacent) nucleotides OR forms sugar- phosphate backbone (1 mark)
Analogy to remember:
Like opening (DNA helicase) and reading (DNA polymerase) a book.
Exam technique:
Emphasise the importance of key terms e.g. "adjacent" and "unwinding" in achieving full marks in regard to A-level mark-schemes (e.g. AQA, OCR Edexcel).
BJ
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