Replication and Repair

DNA polymerase II

scans, verifies and fixes final DNA strand

DNA ligase

binds together the last 2 nucleotide fragments when primer

DNA polymerase I

replaces RNA nucleotides for DNA nucleotides

RNA primase

gives DNA polymerase II something to attach to

DNA polymerase III

uses parent strand to match the complementary nucleotide pair → AT GC

Single-Strand Binding Proteins (SSBs)

holds strands to prevent them from reattaching

Topoisomerase

cuts DNA when it tangles, then reattaches it

Helicase

unzips DNA by breaking H-bonds

Leading Strand

5’ to 3’ direction during DNA replication (towards fork)

Lagging Strand

3’ to 5’ directions during DNA replication (away from fork)

Okazaki Fragments

the piece of new DNA on the lagging strand (chunks)

Semiconservative Replication

a mechanism of DNA replication in which each of the 2 strands of parent DNA is incorporated into a new double-stranded DNA molecule

• partly saving the old