D1.1 DNA Replication

helicase

enzyme that unwinds and separates DNA strands at the replication fork

DNA primase

enzyme that synthesises RNA primers and pairs them with exposed bases on the template strand

DNA polymerase III

enzyme that adds new nucleotides onto the new DNA strand on the 3’ end

DNA polymerase I

enzyme that replaces RNA primers with DNA

DNA ligase

enzyme that joins fragments to complete the sugar-phosphate backbone

leading strand

continuous and single strand synthesised from point of origin to the opening replication fork

lagging strand

new strand synthesised discontinuously against direction of replication

Okazaki fragments

series of short segments on lagging strand joined together by enzymes

semiconservative model of replication

idea that 2 strands of the parental molecule separates and acts as a template for a new complementary strand

excision repair

occurs when any of over 50 repair enzymes remove damanged DNA

PCR

technique used to amplify/make copies of a section of DNA

taq polymerase

enzyme used in PCR tests that are more heat tolerant than DNA polymerase

annealing

process of cooling DNA to allow primers to anneal to ends of single strand`

elongation

process of raising DNA temperature to the ideal temperature needed for taq polymerase to build complementary strands of DNA

agarose

gel used in gel electrophoresis for DNA

polyacrylamide

gel used in gel electrophoresis for proteins