DNA and RNA structure and DNA replication

Learning objectives

Describe the structure of DNA as an antiparallel double helix of nucleotides with complementary base pairing, and compare it with the structure of RNA

Describe semiconservative replication, identifying the roles of helicase, DNA polymerase and ligase and explaining why the leading and lagging strands are synthesized differently

Explain why DNA polymerase can only add nucleotides to the 3′ end of a growing strand and how this produces Okazaki fragments

Compare the organization of the genome in prokaryotes and eukaryotes, including plasmids, chromosomes and the packaging of DNA with histones

Explain how the evidence from experiments such as those of Griffith, Avery and Hershey and Chase supports the claim that DNA is the heritable material