quick need to knows BIO 214

helicase

unwinds the DNA double helix by breaking hydrogen bonds between complementary bases

• unzips DNA

topoisomerase (DNA gyrase)

relieve twisting and supercoiling ahead of the replication fork as DNA is unwound

• relieve tension

single-stranded binding proteins

bind to separated DNA strands and prevent them from joining back together

• keeps strands apart

primase

makes short RNA primers that provides a starting point for DNA synthesis

DNA polyermase III

main bacterial enzyme that adds DNA nucleotides to the growing strands in the 5’ to 3’ direction

• builds new DNA

DNA polyermase I

remove RNA primers and replaces them with DNA nucleotides

• removes and replaces primers

DNA ligase

seals gaps in the sugar-phosphate backbone, especially between the Okazaki fragments on the lagging strand

• glues DNA fragments together

orgin of replication

process where specific DNA sequence starts

leading strand

grows continously towards the replication fork

lagging strand

grows in short pieces called okazaki fragments

DNA ligase

seals the final nicks

topoisomerase IV

untangles and seperates the newly linked circular chromosomes so they can split into daughter cells