Chapter 10

In this chapter, we focused on how DNA is replicated and synthesized. In particular, we elucidated the general mechanism of replication and described how DNA is synthesized when it is copied. Based on your study of these topics, answer the following fundamental questions: (a) What is the experimental basis for concluding that DNA replicates semiconservatively in both bacteria and eukaryotes? (b) How was it demonstrated that DNA synthesis occurs under the direction of DNA polymerase III and not polymerase I? (c) How do we know that in vivo DNA synthesis occurs in the $5^{\prime }$ to $3^{\prime }$ direction? (d) How do we know that DNA synthesis is discontinuous on one of the two template strands? (e) What observations reveal that a "telomere problem" exists during eukaryotic DNA replication, and how did we learn of the solution to this problem?

Compare conservative, semiconservative, and dispersive modes of DNA replication.

Describe the role of ${}^{15}\mathrm{N}$ in the Meselson-Stahl experiment.

Kornberg showed that nucleotides are added to the 3 '-end of each growing DNA strand. In what way does an exposed $3^{\prime }$ - OH group participate in strand elongation?

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

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

Distinguish between (a) unidirectional and bidirectional synthesis, and (b) continuous and discontinuous synthesis of DNA.

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.