Chapter 13.3.2 (Exam 3) DNA Replication

Question 1

What are the 4 things required for DNA replication?

Answer 1

DNA Template

All 4 dNTPs

Enzyme – DNA polymerase

Primer

Question 2

What is a primer?

Answer 2

DNA polymerase requires a primer, a short starter strand—usually RNA

The primer is complementary to the DNA template and is synthesized by a primase

Question 3

How does DNA polymerase use a primer to synthesize DNA strands?

Answer 3

DNA polymerase then adds nucleotides to the 3’ end until that section is complete, and the primer is degraded

Question 4

What are two proteins aside from DNA polymerase that have roles in replication?

Answer 4

DNA helicase

Single-strand binding proteins

Question 5

What is the function of DNA helicase?

Answer 5

DNA helicase uses energy from ATP hydrolysis to unwind the DNA

Question 6

What is the function of single-strand binding proteins?

Answer 6

Single-strand binding proteins keep the strands from getting back together after they are separated by DNA helicase

Question 7

Describe the two strands that are being synthesized during DNA replication.

Answer 7

The leading strand grows at the 3′ end as the fork opens

The lagging strand, the exposed 3′ end gets farther from the fork, and an unreplicated gap forms

Question 8

What is the role of Okazaki fragments?

Answer 8

Synthesis of the lagging strand occurs in small, discontinuous stretches called Okazaki fragments

Each fragment requires its own primer

Question 9

What is the function of DNA polymerase I and III in synthesizing DNA strands?

Answer 9

DNA polymerase III adds nucleotides to the 3′ end, until reaching the primer of the previous fragment

DNA polymerase I then replaces the primer with DNA

Question 10

What is the role of DNA ligase in synthesizing DNA?

Answer 10

The final phosphodiester linkage between Okazaki fragments to create a continuous DNA strand is catalyzed by DNA ligase