GCD Chapter 11 Exam 2

Replication

two complimentary strands seperate and act as templates for two new strands. Half the DNA from each ends up on new strands.

Meselson and Stahl

Discovered replication

oriC

Origin of replication in bacteria.

DnaA boxes

Start of replication. DnaA proteins bind to DnaA

AT rich regions

where DNA strands seperate

GATC methylation sites

help regulate DNA replication

Helicases

seperate DNA outisde oriC by breaking hydrogen bonds

Helicase structure

Use ATP for energy and travel 5-3

DNA gyrase

travels ahead of helicase to alleviate supercoiling

Replication direction

Bidirectionally from origin of rep

DNA polymerase III

make new daughter strands

DNA polymerases

attach new nucleotides from 5-3

RNA primers

Synthesized by DNA primase. Allow DNA polymerase III to start synthesizing the daughter strands

leading strand

made contiuously in direction of replication fork

Lagging strand

Replication occurs away from fork, but still from 5-3 in Okazaki fragments

DNA polymerase I

Removes RNA primers in Okazaki fragments, then fills in DNA using 3 end of the adjacent Okazaki as primer.

Exonuclease (5-3)

Removes nucleotides. Is how DNA polymerase removes primers

DNA ligase

covalently links adjacent Okazaki fragments

Exonuclease(3-5)

Gives DNA polymerase III a proofreading function.

Flap endonuclease

removes peices of RNA flaps that are generated by DNA polymerase delta running into RNA primers of adjacent Okazakis

Telomere replication

accomplished by telomerase enzyme