DNA Synthesis Flashcards
What catalyzes the elongation of new DNA at a replication fork?
DNA Polymerase
What do DNA polymerases require?
A primer sequence and a DNA template strand
What are nucleotides that are added to a growing DNA strand?
Nucleoside triphosphate
What does dATP do?
supplies adenine to DNA
Difference between dATP and ATP?
dATP has deoxyribose while ATP has ribose
What happens when monomers of dATP join DNA?
it loses two phosphate groups as a molecule of pyrophosphate
In what direction is DNA synthesized?
5’ - 3’
DNA polymerase works in direction away from the replication fork
What is the lagging strand made up of?
Okazaki fragments which are joined together by DNA Ligase
What is helicase?
unwinds parental double helix at replication forks
What is the single-strand binding protein?
not an enzyme, binds to and stabilizes single-stranded DNA until it can be used as a template
What is topoisomerase?
Relieves ‘overwinding’ strain ahead of replication forks by breaking, swiveling, and rejoining DNA strands
What is primase?
synthesizes an RNA primer at 5’ end of leading strand and of each Okazaki fragment of lagging strand
What is DNA polymerase I?
removes RNA nucleotides of primer from 5’ end and replaces them with DNA nucleotides
What is DNA polymerase III?
using parental DNA as a template, synthesizes new DNA strand by covalently adding nucleotides to the 3’ end of a pre-existing DNA strand or RNA primer
What is DNA ligase?
joins 3’ end of DNA that replaces primer to rest of leading strand and joins Okazaki fragments of lagging strand.
