Chapter 11 DNA Replication Flashcards
Structure of Helix
2 stands composed of nucleotides A, T, C, G
*held together by hydrogen bonds
Three Mech. for explaining DNA Replication
Which is correct?
Conservative
Semiconservative
Dispersive
(explain experiment and why the correct one is correct)
Bacterial DNA Replication
-Single oriC
-bidirectional
Two replication forks moving in opposite directions
Replication in Bacterial DNA initiated by:
binding of dnaA protein with DnaA box
oriC Region contains 3 types of DNA sequence:
1) AT rich region
2) DnaA box
3) GATC Methylation site
Topo II or Gyrase
Travels in front of helicase and alliveates + supercoiling
Primase
syntesize RNA primers
Leading Strand
Single Primer needed at oriC (DNA Poly 3 attaches)
Lagging Strand
multiple primers mad away from fork and discountinous
DNA Polymerase
Snythesizes DNA in leading and lagging strand
DNA Poly 3
Responsible for most of DNA rep. has 10 subunits (alpha catalyzes bonds btw. nucleotides)
DNA Poly I
removes RNA primers and fills in vacant area with DNA
Okazaki Fragment
created only in lagging strand
DNA Ligase
catalyyzes covalent bond btw. adjacent fragmens after Ok. replication
B Subunits (of polymerase)
form dimer which makes a ring structure allowing polymerase to slide down the strand and synthesize at fast rate
What is function of single strand binding proteins?
Bind to the strands of parental DNA and prevent them from re forming a double helix
What do T1 subunits do?
Termination sequence that stops counterclockwise fork
What does T2 subunit do?
Termination sequence that stops clockwise forks
What are cantenanes?
Two interwined circular molecules resulting from bacterial DNA replication. Seperated by toposiermase
Nuclear DNA has what subunits?
Alpha, Delta, and Epsilon
DNA poly Epsilon involved in?
leading strand synthesis
DNA poly Delta involved in?
Lagging strand synthesis
