Unit 3-Molecular Genetics Lesson 2 1.0

Question 1

When does DNA replication occur?

Answer 1

During cell division and specifically during the S Phase of the Cell Cycle.

Question 2

What is the main purpose of DNA replication?

Answer 2

To accurately copy one DNA molecule into two identical molecules.

Question 3

Who were the key scientists associated with the discovery of DNA structure?

Answer 3

Watson, Crick, and Franklin.

Question 4

What happens to the hydrogen bonds during DNA replication?

Answer 4

The hydrogen bonds between complementary bases break, allowing the DNA to unzip.

Question 5

What is formed as a result of DNA replication?

Answer 5

Two identical DNA molecules, one for each daughter cell.

Question 6

What were the three proposed methods of DNA replication?

Answer 6

1) Conservative, 2) Semi-conservative, 3) Dispersive.

Question 7

What experiment did Meselson and Stahl conduct?

Answer 7

They grew E. coli in 15N media to make the DNA heavy, then transferred it to normal 14N media.

Question 8

What were the outcomes observed by Meselson and Stahl?

Answer 8

New molecules had medium (hybrid) DNA or one molecule had heavy DNA while the other had light DNA.

Question 9

What is the process called that was confirmed by Meselson and Stahl’s experiment?

Answer 9

Semiconservative replication.

Question 10

List the general steps involved in DNA replication.

Answer 10

1) Initiation and unzipping, 2) Priming, 3) Elongation, 4) Proof-reading.

Question 11

Name some key players involved in DNA replication.

Answer 11

DNA polymerase III, DNA polymerase I, Leading strand, Lagging strand, Okazaki fragments, RNA primase, Helicase, Gyrase, Ligase.

Question 12

What begins the process of DNA replication?

Answer 12

Proteins binding at a specific site on the DNA known as the origin of replication (ori).

Question 13

How many origins of replication (ori) do prokaryotic and eukaryotic DNA generally have?

Answer 13

Prokaryotes usually have one origin of replication, while eukaryotic DNA has multiple origins.

Question 14

What role does DNA helicase play in DNA replication?

Answer 14

It unwinds the double helix by breaking the hydrogen bonds at the replication fork.

Question 15

What are Single-stranded Binding Proteins (SSBs) and their function?

Answer 15

SSBs bind to the exposed DNA template strands to block new hydrogen bonds that would re-join the strands.

Question 16

What is the function of DNA gyrase during strand separation?

Answer 16

It relieves tension from the unwinding of the DNA strands by cutting nicks and allowing them to swivel.