Question 1

What enzyme cleaves the DNA backbone to remove the beheaded deoxyribose phosphate during base excision repair?

Accepted Answer

A) an AP endonuclease 
B) phosphodiesterase activity of polymerase  
C) 5'->3' exonuclease 
D) 3'->5' exonuclease 
E) DNA glycosylase 
A) an AP endonuclease 
B) phosphodiesterase activity of polymerase  
C) 5'->3' exonuclease 
D) 3'->5' exonuclease 
E) DNA glycosylase

Question 2

In mammalian cells,a complex of proteins binds to the broken ends of the DNA duplex and catalyzes a series of reactions that rejoin the broken strands.This is an example of what kind of repair?

Accepted Answer

A) nucleotide excision repair 
B) base excision repair 
C) mismatch repair 
D) double-strand breakage repair 
E) nonhomologous end joining 
A) nucleotide excision repair 
B) base excision repair 
C) mismatch repair 
D) double-strand breakage repair 
E) nonhomologous end joining

Question 3

Which DNA polymerase in bacteria synthesizes DNA strands during replication and forms part of a complex that serves as a large replication machine?

Accepted Answer

A) DNA polymerase I 
B) DNA polymerase II 
C) DNA polymerase III 
D) DNA polymerase IV 
E) both DNA polymerase I and DNA polymerase III 
A) DNA polymerase I 
B) DNA polymerase II 
C) DNA polymerase III 
D) DNA polymerase IV 
E) both DNA polymerase I and DNA polymerase III

Question 4

Bacteria are grown in a medium containing 15NH4Cl for a number of generations so that all of the DNA is made of fully "heavy" DNA.The bacteria are moved to a new medium and grown in 15NH4Cl so that all new DNA will be "light".If replication were conservative,what would the DNA look like after two generation times.

Accepted Answer

A) All of the DNA is made of 2 "light" strands. 
B) Half of the DNA is made of 2 "light" strands and half of the DNA is made of 1 "light" strand and 1 "heavy" strand. 
C) All of the DNA is made of 1 "heavy" strand and 1 "light" strand. 
D) Each strand is made of a mixture of "heavy" and "light" DNA with each strand being between 75% and 100% "light". 
E) 75% of the DNA is made of 2 "light" strands and 25% of the DNA is made of 2 "heavy" strands. 
A) All of the DNA is made of 2 "light" strands. 
B) Half of the DNA is made of 2 "light" strands and half of the DNA is made of 1 "light" strand and 1 "heavy" strand. 
C) All of the DNA is made of 1 "heavy" strand and 1 "light" strand. 
D) Each strand is made of a mixture of "heavy" and "light" DNA with each strand being between 75% and 100% "light". 
E) 75% of the DNA is made of 2 "light" strands and 25% of the DNA is made of 2 "heavy" strands.

Question 5

Strand initiation during replication is carried out by an enzyme that makes a short RNA molecule that is used as a primer; the enzyme is a distinct type of RNA polymerase,called _______.

Accepted Answer

A) RNA gyrase 
B) RNA ligase 
C) ribonuclease 
D) primase 
E) deoxyribonuclease 
A) RNA gyrase 
B) RNA ligase 
C) ribonuclease 
D) primase 
E) deoxyribonuclease

Question 6

Where is DNA gyrase normally positioned as it changes positively supercoiled DNA into negatively supercoiled DNA in the replicating circular,bacterial chromosome?

Accepted Answer

A) It is permanently located at the origin. 
B) It travels along the DNA behind the replication fork. 
C) It travels along the DNA ahead of the replication fork. 
D) It travels along the DNA at the replication fork as part of the replisome. 
E) It is permanently located at the termination site of replication. 
A) It is permanently located at the origin. 
B) It travels along the DNA behind the replication fork. 
C) It travels along the DNA ahead of the replication fork. 
D) It travels along the DNA at the replication fork as part of the replisome. 
E) It is permanently located at the termination site of replication.

Question 7

What evidence below suggested that the sequence of DNA was unimportant in the timing of replication?

Accepted Answer

A) The inactive,heterochromatized X chromosome in female mammals replicates late in S phase,while the active euchromatic X chromosome replicates at an earlier stage. 
B) The inactive,heterochromatized X chromosome in female mammals replicates early in S phase,while the active euchromatic X chromosome replicates at a later stage. 
C) The inactive,heterochromatized X chromosome in female mammals replicates late in M phase,while the active euchromatic X chromosome replicates at an earlier stage. 
D) Incorporation of radioactive DNA precursors in replicating cells begins over heterochromatic regions in the nucleus. 
E) Incorporation of radioactive DNA precursors in replicating cells ends over heterochromatic regions in the nucleus. 
A) The inactive,heterochromatized X chromosome in female mammals replicates late in S phase,while the active euchromatic X chromosome replicates at an earlier stage. 
B) The inactive,heterochromatized X chromosome in female mammals replicates early in S phase,while the active euchromatic X chromosome replicates at a later stage. 
C) The inactive,heterochromatized X chromosome in female mammals replicates late in M phase,while the active euchromatic X chromosome replicates at an earlier stage. 
D) Incorporation of radioactive DNA precursors in replicating cells begins over heterochromatic regions in the nucleus. 
E) Incorporation of radioactive DNA precursors in replicating cells ends over heterochromatic regions in the nucleus.

Question 8

What enzyme is responsible for recognizing a chemical alteration in the DNA and removing the base by cleavage of the bond holding the base to the deoxyribose sugar moiety?

Accepted Answer

A) an AP endonuclease 
B) phosphodiesterase activity of polymerase $\beta$ 
C) 5'->3' exonuclease 
D) 3'->5' exonuclease 
E) DNA glycosylase 
A) an AP endonuclease 
B) phosphodiesterase activity of polymerase $\beta$ 
C) 5'->3' exonuclease 
D) 3'->5' exonuclease 
E) DNA glycosylase

Question 9

Cultured mammalian cells grown in thymidine for many generations were allowed to undergo replication in the presence of bromodeoxyuridine (BrdU),which replaces thymidine in DNA.After two rounds of replication,what does the DNA look like?

Accepted Answer

A) All chromatids have one strand that contains BrdU and one strand that does not. 
B) All chromatids have two strands that contain BrdU. 
C) Half of the chromatids have two strands that contain BrdU and half of the chromatids have 2 strands lacking BrdU. 
D) Both strands of each chromatid contain mixtures of BrdU and thymidine. 
E) Half of the chromatids have two strands that contain BrdU and half of the chromatids have 1 strand lacking BrdU and one strand containing BrdU. 
A) All chromatids have one strand that contains BrdU and one strand that does not. 
B) All chromatids have two strands that contain BrdU. 
C) Half of the chromatids have two strands that contain BrdU and half of the chromatids have 2 strands lacking BrdU. 
D) Both strands of each chromatid contain mixtures of BrdU and thymidine. 
E) Half of the chromatids have two strands that contain BrdU and half of the chromatids have 1 strand lacking BrdU and one strand containing BrdU.

Question 10

Where is the DnaB helicase first loaded onto the DNA?

Accepted Answer

A) at the replication terminator site 
B) at the replication origin 
C) at random locations through the circular chromosome 
D) at the operator 
E) at the promoter 
A) at the replication terminator site 
B) at the replication origin 
C) at random locations through the circular chromosome 
D) at the operator 
E) at the promoter

Question 11

The stepwise assembly of nucleosomes and their orderly spacing along the DNA is facilitated by what?

Accepted Answer

A) a network of accessory proteins 
B) a number of histone chaperones that are able to accept newly synthesized histones and transfer them to daughter strands 
C) a number of histone chaperones that are able to accept parental histones and transfer them to daughter strands 
D) CAF-1,which is able to accept either parental histones or newly synthesized histones and transfer them to daughter strands 
E) All of these are correct. 
A) a network of accessory proteins 
B) a number of histone chaperones that are able to accept newly synthesized histones and transfer them to daughter strands 
C) a number of histone chaperones that are able to accept parental histones and transfer them to daughter strands 
D) CAF-1,which is able to accept either parental histones or newly synthesized histones and transfer them to daughter strands 
E) All of these are correct.

Question 12

All DNA polymerases lay down nucleotides in a ______ direction and move along the template in a _______ direction.

Accepted Answer

A) 3'->5',5'->3' 
B) N->C.C->N 
C) 5'->3',3'->5' 
D) C->N,N->C 
E) N->C,5'->3' 
A) 3'->5',5'->3' 
B) N->C.C->N 
C) 5'->3',3'->5' 
D) C->N,N->C 
E) N->C,5'->3'

Question 13

The collection of proteins in eukaryotes that forms the replicative complex is known as the __________.

Accepted Answer

A) replicand 
B) replicon 
C) replisome 
D) replimere 
E) polymerizer 
A) replicand 
B) replicon 
C) replisome 
D) replimere 
E) polymerizer

Question 14

After cuts are made on the two sides of the lesion in nucleotide excision repair,what holds the damaged part of the strand in position for a while before its final removal?

Accepted Answer

A) ionic bonds 
B) van der Waals forces 
C) H bonds 
D) 3'-5' phosphodiester linkages 
E) disulfide linkages 
A) ionic bonds 
B) van der Waals forces 
C) H bonds 
D) 3'-5' phosphodiester linkages 
E) disulfide linkages

Question 15

How does DNA polymerase III move from one site on the lagging strand template to a site closer to replication fork?

Accepted Answer

A) It hitches a ride with the DNA polymerase that is moving that way along the leading strand template. 
B) It hitches a ride with the DNA polymerase that is moving that way along the lagging strand template. 
C) It moves by itself like a tiny molecular motor. 
D) It transports from the earlier Okazaki fragment to the later Okazaki fragment. 
E) It is moved toward the replication fork by a complex of proteins called the transportosome. 
A) It hitches a ride with the DNA polymerase that is moving that way along the leading strand template. 
B) It hitches a ride with the DNA polymerase that is moving that way along the lagging strand template. 
C) It moves by itself like a tiny molecular motor. 
D) It transports from the earlier Okazaki fragment to the later Okazaki fragment. 
E) It is moved toward the replication fork by a complex of proteins called the transportosome.

Question 16

What is the mechanism of action of the anti-HIV drug AZT?

Accepted Answer

A) it causes double-strand DNA breaks 
B) it inhibits DNA synthesis by reverse transcriptase 
C) it prevents transcription in infected cells 
D) it blocks the active site of DNA ligase 
E) it prevents viral entry into cells 
A) it causes double-strand DNA breaks 
B) it inhibits DNA synthesis by reverse transcriptase 
C) it prevents transcription in infected cells 
D) it blocks the active site of DNA ligase 
E) it prevents viral entry into cells

Question 17

In early experiments with DNA polymerase I,what evidence convinced investigators that the original unlabeled DNA in the reaction mixture served as the template for the newly made DNA?

Accepted Answer

A) The new DNA had the same base composition as the original unlabeled DNA. 
B) The new DNA had a variable base composition. 
C) The new DNA had a triple helix. 
D) The new DNA and the old DNA were made of the same elements. 
E) The new DNA was equally stable. 
A) The new DNA had the same base composition as the original unlabeled DNA. 
B) The new DNA had a variable base composition. 
C) The new DNA had a triple helix. 
D) The new DNA and the old DNA were made of the same elements. 
E) The new DNA was equally stable.

Question 18

What type of replication results in the integrity of both parental strands being disrupted? The new duplex strands are made of both old and new DNA.Neither the parental strands nor the parental duplex is preserved.

Accepted Answer

A) semiconservative replication 
B) conservative replication 
C) dispersive replication 
D) incisive replication 
E) reservative replication 
A) semiconservative replication 
B) conservative replication 
C) dispersive replication 
D) incisive replication 
E) reservative replication

Question 19

You are the enzyme responsible for carrying out mismatch repair.You notice a mismatched pair in the DNA strand and you know it is your job to remove one of the bases in the mismatched pair.How would you decide which nucleotide to remove?

Accepted Answer

You would look at the DNA strands and id

Question 20

What is responsible for filling the gap left by the nucleases that digest the primer and the short DNA segment added to it by polymerase ?

Accepted Answer

A) DNA polymerase $\beta$ 
B) DNA polymerase $\delta$ 
C) DNA polymerase $\varepsilon$ 
D) both DNA polymerase $\beta$ and DNA polymerase  $\delta$ 
E) RNase H1 
A) DNA polymerase $\beta$ 
B) DNA polymerase $\delta$ 
C) DNA polymerase $\varepsilon$ 
D) both DNA polymerase $\beta$ and DNA polymerase  $\delta$ 
E) RNase H1

What enzyme cleaves the DNA backbone to remove the beheaded deoxyribose phosphate during base excision repair?

In mammalian cells,a complex of proteins binds to the broken ends of the DNA duplex and catalyzes a series of reactions that rejoin the broken strands.This is an example of what kind of repair?

Which DNA polymerase in bacteria synthesizes DNA strands during replication and forms part of a complex that serves as a large replication machine?

Strand initiation during replication is carried out by an enzyme that makes a short RNA molecule that is used as a primer; the enzyme is a distinct type of RNA polymerase,called _______.

Where is DNA gyrase normally positioned as it changes positively supercoiled DNA into negatively supercoiled DNA in the replicating circular,bacterial chromosome?

What evidence below suggested that the sequence of DNA was unimportant in the timing of replication?

What enzyme is responsible for recognizing a chemical alteration in the DNA and removing the base by cleavage of the bond holding the base to the deoxyribose sugar moiety?

Cultured mammalian cells grown in thymidine for many generations were allowed to undergo replication in the presence of bromodeoxyuridine (BrdU),which replaces thymidine in DNA.After two rounds of replication,what does the DNA look like?

Where is the DnaB helicase first loaded onto the DNA?

The stepwise assembly of nucleosomes and their orderly spacing along the DNA is facilitated by what?

All DNA polymerases lay down nucleotides in a direction and move along the template in a _ direction.

The collection of proteins in eukaryotes that forms the replicative complex is known as the __________.

After cuts are made on the two sides of the lesion in nucleotide excision repair,what holds the damaged part of the strand in position for a while before its final removal?

How does DNA polymerase III move from one site on the lagging strand template to a site closer to replication fork?

What is the mechanism of action of the anti-HIV drug AZT?

In early experiments with DNA polymerase I,what evidence convinced investigators that the original unlabeled DNA in the reaction mixture served as the template for the newly made DNA?

What type of replication results in the integrity of both parental strands being disrupted? The new duplex strands are made of both old and new DNA.Neither the parental strands nor the parental duplex is preserved.

You are the enzyme responsible for carrying out mismatch repair.You notice a mismatched pair in the DNA strand and you know it is your job to remove one of the bases in the mismatched pair.How would you decide which nucleotide to remove?

What is responsible for filling the gap left by the nucleases that digest the primer and the short DNA segment added to it by polymerase ?

Introduction to the Study of Cell and Molecular Biology

The Chemical Basis of Life

Bioenergetics,enzymes and Metabolism

The Structure and Function of the Plasma Membrane

Aerobic Respiration and the Mitochondrion

Photosynthesis and the Chloroplast

Interactions Between Cells and Their Environment

Cytoplasmic Membrane Systems: Structure, function, and Membrane Trafficking

The Cytoskeleton and Cell Motility

The Nature of the Gene and the Genome

Gene Expression: From Transcription to Translation

Control of Gene Expression

Cellular Reproduction

Cell Signaling and Signal Transduction: Communication Between Cells

Cancer

The Immune Response

Techniques in Cell and Molecular Biology

Filters

Exam 13: Dna Replication and Repair

What enzyme cleaves the DNA backbone to remove the beheaded deoxyribose phosphate during base excision repair?

In mammalian cells,a complex of proteins binds to the broken ends of the DNA duplex and catalyzes a series of reactions that rejoin the broken strands.This is an example of what kind of repair?

Which DNA polymerase in bacteria synthesizes DNA strands during replication and forms part of a complex that serves as a large replication machine?

Strand initiation during replication is carried out by an enzyme that makes a short RNA molecule that is used as a primer; the enzyme is a distinct type of RNA polymerase,called _______.

Where is DNA gyrase normally positioned as it changes positively supercoiled DNA into negatively supercoiled DNA in the replicating circular,bacterial chromosome?

What evidence below suggested that the sequence of DNA was unimportant in the timing of replication?

What enzyme is responsible for recognizing a chemical alteration in the DNA and removing the base by cleavage of the bond holding the base to the deoxyribose sugar moiety?

Cultured mammalian cells grown in thymidine for many generations were allowed to undergo replication in the presence of bromodeoxyuridine (BrdU),which replaces thymidine in DNA.After two rounds of replication,what does the DNA look like?

Where is the DnaB helicase first loaded onto the DNA?

The stepwise assembly of nucleosomes and their orderly spacing along the DNA is facilitated by what?

All DNA polymerases lay down nucleotides in a ______ direction and move along the template in a _______ direction.

The collection of proteins in eukaryotes that forms the replicative complex is known as the __________.

After cuts are made on the two sides of the lesion in nucleotide excision repair,what holds the damaged part of the strand in position for a while before its final removal?

How does DNA polymerase III move from one site on the lagging strand template to a site closer to replication fork?

What is the mechanism of action of the anti-HIV drug AZT?

In early experiments with DNA polymerase I,what evidence convinced investigators that the original unlabeled DNA in the reaction mixture served as the template for the newly made DNA?

What type of replication results in the integrity of both parental strands being disrupted? The new duplex strands are made of both old and new DNA.Neither the parental strands nor the parental duplex is preserved.

You are the enzyme responsible for carrying out mismatch repair.You notice a mismatched pair in the DNA strand and you know it is your job to remove one of the bases in the mismatched pair.How would you decide which nucleotide to remove?

What is responsible for filling the gap left by the nucleases that digest the primer and the short DNA segment added to it by polymerase ?

Introduction to the Study of Cell and Molecular Biology

The Chemical Basis of Life

Bioenergetics,enzymes and Metabolism

The Structure and Function of the Plasma Membrane

Aerobic Respiration and the Mitochondrion

Photosynthesis and the Chloroplast

Interactions Between Cells and Their Environment

Cytoplasmic Membrane Systems: Structure, function, and Membrane Trafficking

The Cytoskeleton and Cell Motility

The Nature of the Gene and the Genome

Gene Expression: From Transcription to Translation

Control of Gene Expression

Cellular Reproduction

Cell Signaling and Signal Transduction: Communication Between Cells

Cancer

The Immune Response

Techniques in Cell and Molecular Biology

Filters

All DNA polymerases lay down nucleotides in a direction and move along the template in a _ direction.