Describe the process of semi-conservative replication
Process- key words from mark schemes are highlighted in bold 1. The enzyme DNA helicase breaks the hydrogen bonds linking base pairs of DNA. As a result, the double helix unwinds and into two separate strands. 2. Each exposed polynucleotide strand then acts as a template to which complementary free nucleotides bind by specific base pairing 3. Nucleotides are joined together in a condensation reaction* by the enzyme DNA polymerase to form the “missing” polynucleotide strands of DNA * Condensation reaction: a reaction in which two molecules combine to form a larger molecule, producing a small molecule such as H2O as a by-product. Why is it called semi-conservative replication? The process is referred to as semi-conservative replication because each of the new DNA molecules contains one of the original “template” DNA strands and one strand which is synthesised to be complementary to the “template” from free nucleotides.
