Chapter 12 Practice Exam

What is the function of DNA gyrase? A) Connects Okazaki fragments by sealing nicks in the sugar- phosphate backbone B) Unwinds the double helix by breaking the hydrogen bonding between the two strands at the replication fork C) Reduces the torsional strain that builds up ahead of the replication fork as a result of unwinding D) Binds to oriC and causes a short section of DNA to unwind E) Prevents the formation of secondary structures within single-stranded DNA

C

What type of synthesis occurs on the leading strand? A) Conservative B) Dispersive C) Continuous D) Discontinuous E) Recombination

C

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

If a deletion occurs in a gene that encodes DNA polymerase I and no functional DNA polymerase I is produced. What will be the most likely consequence of this mutation? A) The DNA strands would contain pieces of RNA. B) The DNA would not exist in a supercoiled state. C) There would be no DNA replication on the leading or lagging strands. D) There would be no RNA primers laid down. E) The DNA will not be able to unwind to initiate replication.

A

Okazaki fragments are found in all of the following EXCEPT A) leading strand. B) lagging strand. C) eukaryotic DNA. E) bacterial DNA. D) linear replication models.

A

What is the function of DNA ligase? A) Connects Okazaki fragments by sealing nicks in the sugar- phosphate backbone B) Unwinds the double helix by breaking the hydrogen bonding between the two strands at the replication fork C) Reduces the torsional strain that builds up ahead of the replication fork as a result of unwinding D) Binds to oriC and causes a short section of DNA to unwind E) Prevents the formation of secondary structures within single-stranded DNA

A

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

What type of bonds does DNA ligase create between adjacent nucleotides? A) Hydrogen B) Phosphodiester C) Ionic D) Metallic E) Ribonucleotide

B

What would be a likely result of expressing telomerase in somatic cells? A) Premature aging B) Cancer C) Lower rates of replication D) Immortality of gametes E) Early termination of replication

B

Which of the following does NOT utilize bidirectional replication? A) Theta model B) Rolling circle model C) Linear model D) Eukaryotes E) Bacteria

B

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

For which of the following is the "end-replication problem" relevant? A) Circular DNA B) Linear chromosomes C) The centromere region of a chromosome D) Rolling circle model of replication E) Theta model of replication

B

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

The proofreading function of DNA polymerases involves A) 5′ → 3′ exonuclease activity. B) 3′ → 5′ exonuclease activity. C) 5′ → 3′ telomerase activity. D) 3′ → 5′ telomerase activity. E) 5′ → 3′ gyrase activity.

B

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

_______ are tandemly repeated DNA sequences located at the ends of eukaryotic chromosomes. A) Replication bubbles B) Telomeres C) Nucleosomes D) Licensing factors E) Holliday junctions

B

DNA primase requires a ____ template and _____ nucleotides to initiate primer synthesis. A) DNA; DNA B) RNA; RNA C) DNA; RNA D) RNA; DNA E) leading strand; DNA

C

DNA synthesis during replication is initiated from A) a free 5′ OH. B) DNA primers. C) RNA primers. D) telomerase. E) DNA polymerase I.

C

Which of the following is TRUE of DNA polymerases of eukaryotic cells? A) The same DNA polymerase replicates mitochondrial, chloroplast, and nuclear DNA. B) There are only two different DNA polymerases that function in the process of replication. C) Some DNA polymerases have the ability to function in DNA repair mechanisms. D) All eukaryotic DNA polymerases have 3′ → 5′ exonuclease activity. E) Leading and lagging strand synthesis are performed by the same type of DNA polymerase

C

Which of the following is a protein that facilitates the termination of replication in E. coli? A)Telomerase B) DNA gyrase C) Tus D) Primase E) Topoisomerase

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

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

DNA polymerases require all of the following for DNA replication, EXCEPT A) DNA template. B) primer. C) free 3′ OH. D) 3′ to 5′ polymerase activity. E) dNTPs.

D

Telomerase activity is most likely to be found in which cells in humans? A) Red blood cells B) Muscle cells C) Neurons D) Germ line E) Any type of somatic cell

D

Which activity is NOT associated with DNA polymerases? A) Ability to attach a DNA nucleotide to the 3′ end of previously incorporated DNA nucleotide B) Ability to excise a newly incorporated nucleotide that does not match the template strand C) Ability to "read" a template strand 3′ to 5′ and synthesize a complementary strand D) Ability to synthesize a DNA from scratch without a primer E) Ability to synthesize new DNA in a 5′ to 3′ direction

D

Which of the following is TRUE regarding nucleosome formation during DNA replication? A) Nucleosomes are only reassembled on the lagging strand. B) Nucleosome assembly consists entirely of newly synthesized histones. C) Nucleosome assembly occurs at a faster rate in prokaryotes than in eukaryotes. D) The addition of newly synthesized histones is a part of nucleosome assembly. E) Nucleosome assembly does not occur during semiconservative replication.

D

Which one of the following statements is not true for all E. coli DNA polymerases? A) They require a primer to initiate synthesis. B) They use dNTPs to synthesize new DNA. C) They produce newly synthesized strands that are complementary and antiparallel to the template strands. D) They possess 5′ --> 3′ exonuclease activity. E) They synthesize in the 5′ --> 3′ direction by adding nucleotides to a 3′-OH group.

D

If ribonucleotides were depleted from a cell during S phase, how would DNA synthesis be affected? (Ignore energetic considerations.) A) There would be no effect because ribonucleotides are used in RNA synthesis, not DNA synthesis. B) DNA synthesis would continue, but at a slower rate. C) There would only be an effect during M phase, not in S phase. D) DNA synthesis would not be affected because ribonucleotides are only used during the process of transcription. E) Replication would cease because ribonucleotides are required to initiate DNA synthesis.

E

Telomerase uses _____________ to synthesize new DNA. A) exonuclease activity B) a licensing factor C) strand invasion D) a DNA template E) an RNA template

E

What is the function of single-strand-binding proteins? A) Connects Okazaki fragments by sealing nicks in the sugar- phosphate backbone B) Unwinds the double helix by breaking the hydrogen bonding between the two strands at the replication fork C) Reduces the torsional strain that builds up ahead of the replication fork as a result of unwinding D) Binds to oriC and causes a short section of DNA to unwind E) Prevents the formation of secondary structures within single-stranded DNA

E