Deck 21: Dna Replication II: Detailed Mechanism

Question 1

After DNA replication,bacterial genomes must undergo decatenation before the cell can divide.

Answer 1

True

Question 2

The DNA polymerase III core plus the ____________ is needed to replicate DNA processively. $\beta$

Answer 2

-clamp

Question 3

Which of the following enzymes is responsible for decatenation of Salmonella typhimurium DNA during replication?

A)topoisomerase I
B)topoisomerase II
C)topoisomerase III
D)topoisomerase IV
E)topoisomerase V

Answer 3

D

Question 4

Given the following cell types,which do you propose would have the highest levels of telomerase activity?

A)monkey liver cell
B)macrophage
C)Schwann cell
D)colon cancer cell
E)osteoclast

Question 5

The ends of eukaryotic chromosomes are composed of short GC-rich repeat sequences called ____________.

Question 6

Replication of the SV40 genome is dependent on the viral large T antigen,which has primase activity.

Question 7

In E.coli,DNA replication begins at a unique site,oriC,in the genome.

Question 8

During lagging strand synthesis,it is not uncommon for the DNA polymerase III holoenzyme to dissociate completely from the DNA template for approximately two seconds.

Question 9

DNA replication in eukaryotes always begins at one origin of replication on each chromosome.

Question 10

DNA polymerase III is a highly ___________ enzyme,meaning once it binds DNA it catalyzes the addition of several hundreds of nucleotides without falling of the DNA.

Question 11

Which of the following DNA polymerase III subunits is needed to help "clamp" the $\beta$ -clamp onto DNA?

A) $\alpha$
B) $\varepsilon$
C) $\gamma$ complex
D) $\tau$
E) $\theta$

Question 12

Which of the following subunits of the DNA polymerase III holoenzyme is referred to as the "sliding clamp"?

A) $\alpha$
B) $\beta$
C) $\gamma$
D) $\chi$
E) $\theta$

Question 13

Without telomeres,linear eukaryotic chromosomes would get shorter and shorter with each round of DNA replication.

Question 14

The chromosomal origins of replication vary greatly among bacteria,so much so,that it is hard to propose an origin of replication consensus sequence.

Question 15

Bacterial chromosomes are the only chromosomes known to require decatenation during replication.

Question 16

Yeast origins of replication are located within ____________ that are composed of four important regions.

Question 17

A primosome can be defined as

A)the enzyme that synthesizes primers fro M13 phage replication.
B)a collection of proteins needed for synthesis of primers for replicating DNA.
C)a collection of RNA primers.
D)a DNA molecule that is primed and ready for replication.
E)an area of DNA near the replication fork waiting to be replicated.

Question 18

Telomerase enzyme activity was first observed in extracts from Tetrahymena micronuclei.

Question 19

The DNA polymerase III holoenzyme contains two core enzymes,one that is responsible for ___________ strand synthesis and the other responsible for ____________strand synthesis.

Question 20

In vivo,the DNA polymerase III holoenzyme can synthesize DNA at a rate of

A)250 nt/sec.
B)500 nt/sec.
C)750 nt/sec.
D)1000nt/sec.
E)2000nt/sec.

Question 21

Telomerase is a unique enzyme in that it is composed of only RNA.

Question 22

The eukaryotic processivity factor PCNA serves the same function as the prokaryotic DNA polymerase III $\beta$ -subunit.

Question 23

All eukaryotes must protect their telomeres from nucleases and double strand break repair enzymes.

Question 24

The DNA polymerase III holoenzyme $\gamma$ -complex can act as a clamp loader and unloader.