Chapter 25 DNA Metabolism

Question 1

DNA is replication is semiconservative, this was hypothesized by _____and______. Proved by _____and_______.

Answer 1

Watson and Crick.

Meselson and Stahl.

Question 2

Explain the Meselson-Stahl Experiment.

Answer 2

DNA extracted and centrifuged to equilibrium in CsCl density gradient. Original DNA (parent molecule towards the bottom of test-tube) as replications continue and hybrids form the higher up the sample moved (lowers in density).

Question 3

DNA is replicated during the ___ phase.

Answer 3

S

Question 4

Replication always initiate at the unique point called the ____. This region is __ - rich. Bacterial chromosome only has a single ___ of replication.

Answer 4

origin

AT

origin

Question 5

Eukaryotic chromosomes have multiple origins of replication that are spread out across the chromosome length. Those origins are called ___.

Origins of replication are strictly controlled so
that they ____ only ____ per cell cycle.

Answer 5

ARS

fire, once

Question 6

Each origin of replication initiates the formation of _________ replication forks.

Answer 6

bidirectional

Question 7

DNA synthesis always proceed in __ to __direction and both template strands are copied at a _______ fork.

Answer 7

5, 3

replication

Question 8

Due to the continuous and discontinuous strands replication, DNA synthesis is ____________.

Answer 8

semidiscontinuous

Question 9

According to ______ DNA is synthesized by DNA ___________.

Answer 9

Kornberg, polymerase

Question 10

Hydrolysis of _________

drives DNA synthesis

Answer 10

pyrophosphate

Question 11

In fidelity of replication, error rate is less than _____. Primarily due to 2 factors..

Answer 11

1 in 10^8

(1) Complementary base pairing and (2) Proofreading of DNA polymerase

Question 12

DNA Polymerase 1 contains both DNA Polymerase active site and the 3’ to 5’ proofreading ________ active site. Mismatched pairs occurs in ____________ and is corrected in the ________ end.

Answer 12

exonuclease

DNA polymerase

Exonuclease

Question 13

DNA polymerase catalytic subunit is not very processive (i.e. it falls off the DNA easily). A _________ is required to keep catalytic subunit on and allow duplication of long stretches of DNA

Answer 13

sliding clamp

Question 14

A ________ (gamma, delta, delta’) complex is required to get the clamp onto the DNA

Answer 14

clamp loader