DNA Replication

1) Describe Meselson and Stahl's experiment. Be sure you understand the methodology, and why the results of the first and second generations falsified the conservative model and dispersive models, respectively.

2) What does gyrase do, and why is that neccessary?

3) What is a "replisome"? List the major enzymes and their function that are a part of this "cellular machine".

4) In the replisome, there is a DNA polymerase "dimer" that synthesizes DNA on BOTH strands. How is this accomplished, if the templates are anti-parallel and the polymerases can only synthesize 5'--> 3' ?

5) Explain why Okazaki fragments are formed on the lagging strand (at each fork).

6) Why is DNA synthesis initiated with RNA production?

7) How is the exonuclease activity AND polymerase activity of DNA polymerase I and II used in the repair process?

8) What problem in DNA replication occurs at the end of linear (eukaryotic) chromosomes?

9) How does telomerase solve this problem? Be sure to describe the function of the rna portion of the telomerase.

10) What is the trade-off between having cells divide alot and not having them divide at all? (Give costs and benefits of each).