AP Bio Unit 6 Topic 2

Topoisomerase

Relaxes the supercoiled DNA

Helicase

unwind the DNA strands by breaking the Hydrogen bonds between the nitrogenous bases

single strand binding proteins (SSBPs)

binds to the single strand of DNA to stabilize it

Primase

initiates replication by adding short segments of RNA, called primers, to the parental DNA strand

DNA Polymerase III (DNAP III)

attaches to each primer on the parental strand and moves (reads) in the 3’ to 5’ direction (creates in 5’ to 3’)

Okazaki fragments

segments of the lagging strand

Exonuclease

removes the RNA primer

DNA polymerase I (DNAP I)

replaces RNA nucleotides with DNA nucleotides

DNA ligase

joins the okazaki fragments forming a continuous DNA strand

What model is DNA Replication (Conservative, Semi Conservative, or Dispersive

Semi-Conservative each DNA double helix has one strand of new and one old one.

Difference between Leading and Lagging strand

Leading- the DNAPIII goes towards the replication fork and replicates in one complete motion (the parent strand would be 3’ to 5’ since DNAPIII reads that way)

Lagging- the DNAPIII goes away from the replication fork and has to replicate in segments called Okazaki fragments.