Chapter 12 Flashcards
All DNA polymerases synthesize new DNA by adding nucleotides to the _____ of the growing DNA chain.
a. 3′ OH
b. 5′ OH
c. 3′ phosphate
d. 5′ phosphate
e. nitrogenous base
a
Okazaki fragments are found in all of the following EXCEPT
a. leading strand.
b. lagging strand.
c. eukaryotic DNA.
d. bacterial DNA.
e. linear replication models.
a
Which of the following does NOT utilize bidirectional replication?
a. Theta model
b. Rolling circle model
c. Linear model
d. Eukaryotes
e. Bacteria
b
Which of the following typically only has one origin of replication?
a. Prokaryotes
b. Eukaryotes
c. Linear model of replication
d. Humans
e. Plants
a
Meselson and Stahl showed that DNA is replicated by a __________ system.
a. conservative
b. semiconservative
c. dispersive
d. semidispersive
e. conservative in prokaryotes and dispersive in eukaryotes
b
What type of synthesis occurs on the leading strand?
a. Conservative
b. Dispersive
c. Continuous
d. Discontinuous
e. Recombination
c
- In the diagram below, which letter indicates the 5′ end of the leading strand?
a. A
b. B
c. C
d. D
e. C and D
c
Suppose that some cells are grown in culture in the presence of radioactive nucleotides for many generations so that both strands of every DNA molecule include radioactive nucleotides. The cells are then harvested and placed in new medium with nucleotides that are not radioactive so that newly synthesized DNA will not be radioactive. What proportion of DNA molecules will contain radioactivity after two rounds of replication?
a. 0
b. 1/8
c. 1/4
d. 1/3
e. 1/2
e
You learn that a Mars lander has retrieved a bacterial sample from the polar ice caps. You obtain a sample of these bacteria and perform the same kind of experiment that Meselson and Stahl did to determine how the Mars bacteria replicate their DNA. Based on the following equilibrium density gradient centrifugation results, what type of replication would you propose for these new bacteria?
a. Conservative
b. Semiconservative
c. Dispersive
d. Semiconservative or Dispersive
e. Conservative or Dispersive
c
You are studying a new virus with a DNA genome of 12 Kb. It can synthesize DNA at a rate of 400 nucleotides per second. If the virus uses rolling-circle replication, how long will it take to replicate its genome?
a. 7.5 seconds
b. 15 seconds
c. 30 seconds
d. 1 minute
e. 2 minutes
c
You are studying a new virus with a DNA genome of 12 Kb. It can synthesize DNA at a rate of 400 nucleotides per second. If the virus uses theta replication, how long will it take to replicate its genome?
a. 7.5 seconds
b. 15 seconds
c. 30 seconds
d. 1 minute
e. 2 minutes
b
The nuclear genome of a single human cell (i.e., the entire diploid complement) contains about 6.6 billion (6.6 × 109) base pairs of DNA. If synthesis at each replication fork occurs at an average rate of 50 nucleotides per second, all the DNA is replicated in 5 minutes. Assume that replication is initiated simultaneously at all origins. How many origins of replication exist in a human diploid genome?
a. 220,000
b. 440,000
c. 880,000
d. 2.64 x 107
e. 1.32 x 108
a
The nuclear genome of a single human cell (i.e., the entire diploid complement) contains about 6.6 billion (6.6 × 109) base pairs of DNA. If synthesis at each replication fork occurs at an average rate of 50 nucleotides per second, all the DNA is replicated in 5 minutes. Assume that replication is initiated simultaneously at all origins. Assuming that the origins are approximately equally distributed across the chromosomes, what is the average number of origins per human chromosome?
a. 4783
b. 19,130
c. 4.6 x 106
d. 1.21 x 109
e. 2.9 x 1010
a
Suppose Meselson and Stahl had obtained the following results in their experiment. These results would be consistent with which model of replication?
a. Conservative replication only
b. Semiconservative and conservative replication
c. Semiconservative replication only
d. Dispersive replication only
e. Semiconservative and dispersive replication
e
Which of the following enzymes do NOT aid in unwinding of DNA for replication?
a. Helicase
b. Single-stranded binding proteins
c. Primase
d. Gyrase
e. Topoisomerase
c
DNA polymerase I and DNA polymerase III both have ______but only DNA polymerase I has _______.
a. 5′→ 3′ exonuclease activity; 3′→5′ exonuclease activity
b. 5′→ 3′ polymerase activity; 3′→5′ polymerase activity
c. 3′→5′ polymerase activity; 5′→ 3′ polymerase activity
d. 3′→5′ exonuclease activity; 5′→ 3′ exonuclease activity
e. 5′→ 3′ polymerase activity; 3′→5′ exonuclease activity
d