DNA replication and repair Flashcards
Define: replication
Replication is the biological duplication of the information within DNA to produce two identical replicas of DNA from one original DNA molecule.
Define: polymerase
An enzyme that synthesises long chains of polymers or nucleic acids by copying a template using base pairing interactions.
Define: helicase
An enzyme that uses energy from ATP hydrolysis to unwind the helix shape of DNA and separate the two strands to allow replication to occur.
Define: ligase
An enzyme that attaches DNA fragments together by a phosphodiester bond; especially used to ensure continuation of the lagging strand and in DNA repair.
Define: primase
An enzyme that synthesises the primer DNA one nucleotide at a time (like DNA polymerase).
Define: primer
A starter strand of RNA that is complimentary to the DNA template and serves as a starting point for DNA synthesis.
Define: leading strand
Made by continuous synthesis from a single primer.
Define: lagging strand
Made by synthesis of short Okazaki fragments (100-200 nucleotides) from multiple primers.
Define: replication origin
(aka ori) - found in all chromosomes or defined by a 245 bp DNA sequence in e.coli- a particular sequence in a genome at which replication is initiated.
Define: telomere
A repetitive sequence at the ends of eukaryotic chromosomes which repeat to act to protect and prolong cell division especially in rapidly-dividing cells like bone marrow.
Define: PCR
(polymerase chain reaction) - method used to amplify a specific DNA segment to be able to analyse it more in depth.