replication Flashcards
how are both new strands synthesised
in a 5’ to 3’ direction and both strands grow discontinuously ‘backstitching’
what do Okazaki fragments do
ligated together to form a continuous new strand
why is RNA needed to help with DNA replication
as DNA polymerase only extends double stranded chains
what does the enzyme primase do
it releases an RNA primer
where is the RNA primer found
on the replication origin (leading strand) or at the origin of each okasaki fragment (lagging strand)
how big are RNA primers
they are small (about 10 base pairs) and prime the 5’ to 3’ synthesis of okasaki fragments
what does nuclease do
removes the primer and repair polymerase fills the gap which is joined by DNA ligase (glue)
what does helices do
opens the double helix
what does the clamp do
holds DNA polymerase on DNA
What do single-stranded binding proteins do
prevent the double helix reforming in reannealing
how is DNA polymerase self-correcting
it has exonuclease activity located in a separate domain (exo) from the polymerase domain (pol). Mismatched bases cause the growing strand to flip into the exo domain, where they are cut out
what does replication involve
many enzymes
what starts DNA replication
RNA Primers that are madly primate
what does DNA polymerase proof-read
the new DNA strand
