8. DNA Replication

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?

What was the significance of the polA1 mutation?

Explain how RNA participates in DNA replication.

Summarize and compare the properties of DNA polymerase I, II, and III.

A sample of double-stranded DNA is found to contain 20% cytosine. Determine the percentage of the three other DNA nucleotides in the sample.

List and describe the function of the ten subunits constituting DNA polymerase III. Distinguish between the holoenzyme and the core enzyme.

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?

Bacterial DNA polymerase I and DNA polymerase III perform different functions during DNA replication.

Identify the principal functions of each molecule.

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?

Distinguish between

(a) unidirectional and bidirectional synthesis, and

(b) continuous and discontinuous synthesis of DNA.

Diagram a replication fork in bacterial DNA and label the following structures or molecules.

a. DNA pol III

b. Helicase

c. RNA primer

d. Origin of replication

e. leading strand (label its polarity)

f. DNA pol I

g. Topoisomerase

h. SSB protein

i. Lagging strand (label its polarity)

j. Primase

k. Okazaki fragment

List the proteins that unwind DNA during in vivo DNA synthesis. How do they function?

Define and indicate the significance of

(a) Okazaki fragments,

(b) DNA ligase, and

(c) primer RNA during DNA replication.

Outline the current model for DNA synthesis.

Why is DNA synthesis expected to be more complex in eukaryotes than in bacteria? How is DNA synthesis similar in the two types of organisms?