Genetics Final Exam Questions and Correct Answers (Verified by Expert)
1. What is the function of single-strand-binding proteins?
A. unwind the double helix by breaking hydrogen bonding between the two
strands at the replication fork
B. bind to oriC and cause a short section of DNA to unwind
C. connect Okazaki fragments by sealing nicks in the sugar-phosphate back-
bone
D. prevent the formation of secondary structures within single-stranded DNA
E. reduce the torsional strain that builds up ahead of the replication fork
as a result of winding: prevent the formation of secondary structures within
single-stranded DNA
2. DNA polymerase I and DNA polymerase III both have activity but
only DNA polymerase I has activity.
A. 3'-5' exonuclease, 5'-3' exonuclease
B. 5'-3' polymerase, 3'-5' exonuclease
C. 3'-5' polymerase, 3'-5' polymerase
D. 5'-3' polymerase, 3'-5' polymerase
E. 5'-3' exonuclease, 3'-5' exonuclease: 32 - 52 exonuclease; 52 - 32 exonucleas
3. The Holliday model describes which of the following processes?: homolo-
gous recombination
4. What is the function of DNA gyrase?
A. connects w okazaki fragments by sealing nicks in the sugar phosphate
backbone
B. prevents the formation of secondary structures within single stranded
DNA
C. binds to oriC and causes a short section of DNA to unwind
D. unwinds the double helix by breaking the hydrogen bonding between the
two strands at the replication fork
E. reduces the torsional strain that builds up ahead of the replication fork as
a result of unwinding: reduces the torsional strain that builds up ahead of the
replication fork as a result of unwinding
5. The nuclear genome of a single human cell (i.e., the entire diploid comple-
ment) contains about 6.6 billion (6.6 × 109) base pairs of DNA. If synthesis
at each replication fork moves along the template at an average rate of 50
nucleotides per second and all the DNA is replicated in 5 minutes, how many
origins of replication exist in a human diploid cell? Assume that replication
, Genetics Final Exam Questions and Correct Answers (Verified by Expert)
is initiated simultaneously at all origins.
A. 888,000
B. 2.64 x 107
C. 1.32 x 108
D. 440,000
E. 220,000: 220,000
6. Approximately 6.6 Gb of DNA is present in a single-celled human zygote
and must be replicated faithfully at each cell division. What is the approxi-
mate size of the haploid human genome?
A. 1Mb
B. 6.6 Gb
C. 3.2 Gb
D. 3.2 Mb
E. 12.8 Gb: 3.2 Gb
7. 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?
(check image under question 7, take-home 9)
A. semiconservative or dispersive
B. semiconservative
C. conservative or dispersive
D. conservative
E. dispersive: dispersive
8. Which of the results (A through F) would give a clear experimental com-
parison to distinguish between the semiconservative model and dispersive
model?
(check image under question 8, take home 9)
A. B and E
B. D and F
C. E and F
, Genetics Final Exam Questions and Correct Answers (Verified by Expert)
D. A and D
E. C and F: D and E
9. Which of the following does NOT utilize bidirectional replication?
A. rolling-circle model
B. eukaryotes
C. bacteria
D. theta model
E. linear model: rolling-circle model
10. 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? An-
swer only for the first strand; ignore replication along the displaced strand.
A. 1 minute
B. 2 minutes
C. 30 seconds
D. 7.5 seconds
E. 15 seconds: 30 seconds
11. Okazaki fragments are found in all of the following EXCEPT in
A. linear replication models
B. bacterial DNA
C. the leading strand
D. eukaryotic DNA
E. the lagging strand: the leading strand.
12. Which activity is NOT associated with DNA polymerases?
A. ability to synthesize a DNA from scratch without a primer
B. ability to synthesize new DNA in a 52 to 32 direction
C. ability to excise a newly incorporated nucleotide that does not match the
template strand
D. ability to "read" a template strand 32 to 52 and synthesize a complementar
strand
E. ability to attach a DNA nucleotide to the 32 end of previously incorporated
DNA nucleotide: ability to synthesize a DNA from scratch without a primer
13. The diagram shown below is one half of a replication bubble. As the
DNA template strands unwind toward the right, new strands of DNA get
1. What is the function of single-strand-binding proteins?
A. unwind the double helix by breaking hydrogen bonding between the two
strands at the replication fork
B. bind to oriC and cause a short section of DNA to unwind
C. connect Okazaki fragments by sealing nicks in the sugar-phosphate back-
bone
D. prevent the formation of secondary structures within single-stranded DNA
E. reduce the torsional strain that builds up ahead of the replication fork
as a result of winding: prevent the formation of secondary structures within
single-stranded DNA
2. DNA polymerase I and DNA polymerase III both have activity but
only DNA polymerase I has activity.
A. 3'-5' exonuclease, 5'-3' exonuclease
B. 5'-3' polymerase, 3'-5' exonuclease
C. 3'-5' polymerase, 3'-5' polymerase
D. 5'-3' polymerase, 3'-5' polymerase
E. 5'-3' exonuclease, 3'-5' exonuclease: 32 - 52 exonuclease; 52 - 32 exonucleas
3. The Holliday model describes which of the following processes?: homolo-
gous recombination
4. What is the function of DNA gyrase?
A. connects w okazaki fragments by sealing nicks in the sugar phosphate
backbone
B. prevents the formation of secondary structures within single stranded
DNA
C. binds to oriC and causes a short section of DNA to unwind
D. unwinds the double helix by breaking the hydrogen bonding between the
two strands at the replication fork
E. reduces the torsional strain that builds up ahead of the replication fork as
a result of unwinding: reduces the torsional strain that builds up ahead of the
replication fork as a result of unwinding
5. The nuclear genome of a single human cell (i.e., the entire diploid comple-
ment) contains about 6.6 billion (6.6 × 109) base pairs of DNA. If synthesis
at each replication fork moves along the template at an average rate of 50
nucleotides per second and all the DNA is replicated in 5 minutes, how many
origins of replication exist in a human diploid cell? Assume that replication
, Genetics Final Exam Questions and Correct Answers (Verified by Expert)
is initiated simultaneously at all origins.
A. 888,000
B. 2.64 x 107
C. 1.32 x 108
D. 440,000
E. 220,000: 220,000
6. Approximately 6.6 Gb of DNA is present in a single-celled human zygote
and must be replicated faithfully at each cell division. What is the approxi-
mate size of the haploid human genome?
A. 1Mb
B. 6.6 Gb
C. 3.2 Gb
D. 3.2 Mb
E. 12.8 Gb: 3.2 Gb
7. 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?
(check image under question 7, take-home 9)
A. semiconservative or dispersive
B. semiconservative
C. conservative or dispersive
D. conservative
E. dispersive: dispersive
8. Which of the results (A through F) would give a clear experimental com-
parison to distinguish between the semiconservative model and dispersive
model?
(check image under question 8, take home 9)
A. B and E
B. D and F
C. E and F
, Genetics Final Exam Questions and Correct Answers (Verified by Expert)
D. A and D
E. C and F: D and E
9. Which of the following does NOT utilize bidirectional replication?
A. rolling-circle model
B. eukaryotes
C. bacteria
D. theta model
E. linear model: rolling-circle model
10. 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? An-
swer only for the first strand; ignore replication along the displaced strand.
A. 1 minute
B. 2 minutes
C. 30 seconds
D. 7.5 seconds
E. 15 seconds: 30 seconds
11. Okazaki fragments are found in all of the following EXCEPT in
A. linear replication models
B. bacterial DNA
C. the leading strand
D. eukaryotic DNA
E. the lagging strand: the leading strand.
12. Which activity is NOT associated with DNA polymerases?
A. ability to synthesize a DNA from scratch without a primer
B. ability to synthesize new DNA in a 52 to 32 direction
C. ability to excise a newly incorporated nucleotide that does not match the
template strand
D. ability to "read" a template strand 32 to 52 and synthesize a complementar
strand
E. ability to attach a DNA nucleotide to the 32 end of previously incorporated
DNA nucleotide: ability to synthesize a DNA from scratch without a primer
13. The diagram shown below is one half of a replication bubble. As the
DNA template strands unwind toward the right, new strands of DNA get
