Download Some Replication Questions

Objectives - Replication
1. Prior to the work of Meselson and Stahl (1958), three models regarding the mode of
DNA replication prevailed. Describe conservative, semi-conservative and dispersive
replication.
2. Describe and explain the Meselson and Stahl experiment which provided the evidence
that DNA replication did proceed in a semi-conservative manner.
a) You should understand the foundations of this experiment and be able to
interpret and draw conclusions from alternative results.
3. Describe the structure of oriC in E.coli.
4. How is replication initiated at oriC?
5. Differentiate between the replication fork, a replicon, replication origin.
6. Why is an RNA primer necessary in the replication process?
7. What are the main roles of DNA pol I, II, and III?
8. The 3D structure of DNA polymerase is thought to resemble a cupped right hand.
Explain the function of each component (palm, fingers and thumb).
9. Describe and explain the experiment of Reiji Okazaki and colleagues which provided
the evidence that DNA replication occurred in a semi-discontinuous manner (meaning
that there is a leading strand and a lagging strand).
a) You should understand the foundations of this experiment and be able to
interpret and draw conclusions from alternative results.
10. Distinguish between continuous and discontinuous DNA synthesis.
11. Be sure you know the functions of all of the replication enzymes discussed in class:
DnaA, DnaB, DnaC, SSBPs, DNA gyrase, Primase (DnaG), Sliding clamp, DNA pol I,
DNA pol III, Clamp loader, RNAse H, DNA ligase.
12. What does bidirectional DNA replication accomplish for the cell?
13. How many replication origins can be found in E. coli? How many can be found in a
typical eukaryotic genome?
14. Compare and contrast prokaryotic replication origins with eukaryotic origins (both
structurally and what enzymes bind in order to initiate replication).
15. Describe the function of telomerase and telomere formation.
16. What is meant by "proof-reading"? How is this associated with the 3' to 5'
exonuclease activity of DNA pol I?
17. Differentiate between a nuclease, an exonuclease and an endonuclease.