8. DNA Replication

Overview of DNA Replication

Open Question
Predict the results of the experiment by Taylor, Woods, and Hughes if replication were (a) conservative and (b) dispersive.
Open Question
What are the requirements for in vitro synthesis of DNA under the direction of DNA polymerase I?
Open Question
In Kornberg's initial experiments, it was rumored that he grew E. coli in Anheuser-Busch beer vats. (Kornberg was working at Washington University in St. Louis.) Why do you think this might have been helpful to the experiment?
Open Question
How did Kornberg assess the fidelity of DNA polymerase I in copying a DNA template?
Open Question
Which characteristics of DNA polymerase I raised doubts that its in vivo function is the synthesis of DNA leading to complete replication?
Open Question
DNA polymerase III is the main DNA-synthesizing enzyme in bacteria. Describe how it carries out its role of elongating a strand of DNA.
Open Question
Kornberg showed that nucleotides are added to the 3' end of each growing DNA strand. In what way does an exposed 3'-OH group participate in strand elongation?
Open Question
What was the significance of the polA1 mutation?
Open Question
Explain how RNA participates in DNA replication.
Open Question
Summarize and compare the properties of DNA polymerase I, II, and III.
Open Question
A sample of double-stranded DNA is found to contain 20% cytosine. Determine the percentage of the three other DNA nucleotides in the sample.
Open Question
List and describe the function of the ten subunits constituting DNA polymerase III. Distinguish between the holoenzyme and the core enzyme.
Open Question
Bacterial DNA polymerase I and DNA polymerase III perform different functions during DNA replication.

If a strain of E. coli acquired a mutation that inactivated DNA polymerase III function, would the cell be able to replicate its DNA? Why or why not?
Open Question
Bacterial DNA polymerase I and DNA polymerase III perform different functions during DNA replication.

Identify the principal functions of each molecule.
Open Question
Bacterial DNA polymerase I and DNA polymerase III perform different functions during DNA replication.

If mutation inactivated DNA polymerase I in a strain of E. coli, would the cell be able to replicate its DNA? If so, what kind of abnormalities would you expect to find in the cell?