Chapter 11 Textbook Gentics

What did Meselson and Stahl demonstrate in 1958 regarding DNA replication in E. coli?

They showed that E. coli utilizes semiconservative replication, where newly synthesized DNA consists of one old strand and one new strand.

What method did Taylor, Woods, and Hughes use to demonstrate semiconservative replication in eukaryotes?

They used the root tips of the broad bean as the source of dividing cells.

Who isolated DNA polymerase I from E. coli, and what did he demonstrate?

Arthur Kornberg isolated DNA polymerase I and showed that it can direct in vitro DNA synthesis with a template and precursor nucleoside triphosphates.

What question did the discovery of the polA1 mutant strain of E. coli raise?

It cast doubt on the hypothesized in vivo replicative function of DNA polymerase I.

Which enzyme has been identified as the primary enzyme responsible for DNA replication in vivo?

DNA polymerase III.

What happens during the initiation of DNA synthesis?

The double helix unwinds, forming a replication fork where synthesis begins.

What role do proteins play during DNA synthesis initiation?

They stabilize the unwound helix and help relax the coiling tension ahead of the replication fork.

What is the role of primase during DNA synthesis?

Primase initiates DNA synthesis at specific sites by creating short RNA segments that allow DNA polymerase III to begin polymerization.

How does DNA synthesis occur on the leading and lagging strands?

Synthesis occurs continuously on the leading strand and discontinuously on the lagging strand.