Question 1

Which of the following statements about the newly synthesized strand of a human chromosome is TRUE?

Accepted Answer

A) It was synthesized from a single origin solely by continuous DNA synthesis. 
B) It was synthesized from a single origin by a mixture of continuous and discontinuous DNA synthesis. 
C) It was synthesized from multiple origins solely by discontinuous DNA synthesis. 
D) It was synthesized from multiple origins by a mixture of continuous and discontinuous DNA synthesis. 
A) It was synthesized from a single origin solely by continuous DNA synthesis. 
B) It was synthesized from a single origin by a mixture of continuous and discontinuous DNA synthesis. 
C) It was synthesized from multiple origins solely by discontinuous DNA synthesis. 
D) It was synthesized from multiple origins by a mixture of continuous and discontinuous DNA synthesis. D

Question 2

Several members of the same family were diagnosed with the same kind of cancer when they were unusually young.Which one of the following is the most likely explanation for this phenomenon? It is possible that the individuals with the cancer have inherited

Accepted Answer

A) a cancer-causing gene that suffered a mutation in an ancestor's somatic cells. 
B) a mutation in a gene required for DNA synthesis. 
C) a mutation in a gene required for mismatch repair. 
D) a mutation in a gene required for the synthesis of purine nucleotides. 
A) a cancer-causing gene that suffered a mutation in an ancestor's somatic cells. 
B) a mutation in a gene required for DNA synthesis. 
C) a mutation in a gene required for mismatch repair. 
D) a mutation in a gene required for the synthesis of purine nucleotides. C

Question 3

In terms of its function, is telomerase more like DNA polymerase or Primase? Explain your reasoning.

Accepted Answer

Primase is a type of RNA polymerase, making RNA primers necessary for strand elongation by DNA polymerase.Telomerase is more like DNA polymerase and is highly specialized to help complete DNA replication on the lagging strand.Telomerase carries its own RNA primer, which pairs to repeated sequences in the telomeric region of the chromosome.It then synthesizes new DNA to extend the repeats.

Question 4

Telomeres serve as caps protecting the ends of linear chromosomes.Which of the following is FALSE regarding the replication of telomeric sequences?

Accepted Answer

A) The lagging-strand telomeres are not completely replicated by DNA polymerase. 
B) Telomeres are made of repeating sequences. 
C) Additional repeated sequences are added to the template strand. 
D) The leading strand doubles back on itself to form a primer for the lagging strand. 
A) The lagging-strand telomeres are not completely replicated by DNA polymerase. 
B) Telomeres are made of repeating sequences. 
C) Additional repeated sequences are added to the template strand. 
D) The leading strand doubles back on itself to form a primer for the lagging strand.

Question 5

In somatic cells, if a base is mismatched in one new daughter strand during DNA replication, and is not repaired, what fraction of the DNA duplexes will have a permanent change in the DNA sequence after the second round of DNA replication?

Accepted Answer

A) 1/2 
B) 1/4 
C) 1/8 
D) 1/16 
A) 1/2 
B) 1/4 
C) 1/8 
D) 1/16

Question 6

Match between columns
                        Premises: The repair polymerase is the enzyme that proofreads the newly synthesized strands to ensure the accuracy of DNA replication.

DNA ligase is required to seal the sugar-phosphate backbone between all the DNA fragments on the lagging strand.

There is a single enzyme that degrades the RNA primers and lays down the corresponding DNA sequence behind it.

The repair polymerase does not require the aid of the sliding clamp, because it is only synthesizing DNA over very short stretches.

Accepted Answer

The Answer of False and True is...

Question 7

How many replication forks are formed when an origin of replication is opened?

Accepted Answer

A) 1 
B) 2 
C) 3 
D) 4 
A) 1 
B) 2 
C) 3 
D) 4

Question 8

Beside the distortion in the DNA backbone caused by a mismatched base pair, what additional mark is there on eukaryotic DNA to indicate which strand needs to be repaired?

Accepted Answer

A) a nick in the template strand 
B) a chemical modification of the new strand 
C) a nick in the new strand 
D) a sequence gap in the new strand 
A) a nick in the template strand 
B) a chemical modification of the new strand 
C) a nick in the new strand 
D) a sequence gap in the new strand

Question 9

Which diagram accurately represents the directionality of DNA strands at one side of a replication fork? (a)

(b)

(c)

(d)
 
 Figure 6-19

Accepted Answer

A) Diagram A 
B) Diagram B 
C) Diagram C 
D) Diagram D 
A) Diagram A 
B) Diagram B 
C) Diagram C 
D) Diagram D

Question 10

The process of DNA replication requires that each of the parental DNA strands be used as a __________ to produce a duplicate of the opposing strand.

Accepted Answer

A) catalyst 
B) competitor 
C) template 
D) copy 
A) catalyst 
B) competitor 
C) template 
D) copy

Question 11

DNA polymerases are processive, which means that they remain tightly associated with the template strand while moving rapidly and adding nucleotides to the growing daughter strand.Which piece of the replication machinery accounts for this characteristic?

Accepted Answer

A) helicase 
B) sliding clamp 
C) single-strand binding protein 
D) primase 
A) helicase 
B) sliding clamp 
C) single-strand binding protein 
D) primase

Question 12

A mismatched base pair causes a distortion in the DNA backbone.If this were the only indication of an error in replication, the overall rate of mutation would be much higher.Explain why.

Accepted Answer

The distortion in the DNA backbone is in

Question 13

How does the total number of replication origins in bacterial cells compare to the number of origins in human cells?

Accepted Answer

A) 1 versus 100 
B) 5 versus 500 
C) 10 versus 1000 
D) 1 versus 10,000 
A) 1 versus 100 
B) 5 versus 500 
C) 10 versus 1000 
D) 1 versus 10,000

Question 14

You prepare bacterial cell extracts by lysing the cells and removing insoluble debris via centrifugation.These extracts provide the proteins required for DNA replication.Your DNA template is a small, double-stranded circular piece of DNA (a plasmid) with a single origin of replication and a single replication termination site.The termination site is on the opposite side of the plasmid from the origin.   Figure 6-11
What part of the DNA replication process would be most directly affected if a strain of bacteria lacking DNA ligase were used to make the cell extracts?

Accepted Answer

A) initiation of DNA synthesis 
B) Okazaki fragment synthesis 
C) leading-strand elongation 
D) lagging-strand completion 
A) initiation of DNA synthesis 
B) Okazaki fragment synthesis 
C) leading-strand elongation 
D) lagging-strand completion

Question 15

DNA replication is considered semiconservative because

Accepted Answer

A) after many rounds of DNA replication, the original DNA double helix is still intact. 
B) each daughter DNA molecule consists of two new strands copied from the parent DNA molecule. 
C) each daughter DNA molecule consists of one strand from the parent DNA molecule and one new strand. 
D) new DNA strands must be copied from a DNA template. 
A) after many rounds of DNA replication, the original DNA double helix is still intact. 
B) each daughter DNA molecule consists of two new strands copied from the parent DNA molecule. 
C) each daughter DNA molecule consists of one strand from the parent DNA molecule and one new strand. 
D) new DNA strands must be copied from a DNA template.

Question 16

Match between columns
                        Premises: The first step in repair requires a nuclease to remove a stretch of base pairs from the 5? end of each strand at the site of the break.
The 3? overhang "invades" the homologous DNA duplex, which can be used as a primer for the repair DNA polymerase.

The DNA template used to repair the broken strand is the homologous chromosome inherited from the other parent.

Homologous recombination cannot occur in prokaryotic cells, because they are haploid, and therefore have no extra copy of the chromosome to use as a template for repair.

Accepted Answer

The Answer of False and True is...

Question 17

Recombination has occurred between the chromosome segments shown in Figure 6-40.The genes A and B, and the recessive alleles a and b, are used as markers on the maternal and paternal chromosomes, respectively.After alignment and homologous recombination, the specific arrangements of A, B, a, and b have changed.   Figure 6-40
Which of the choices below correctly indicates the gene combination from the replication products of the maternal chromosome?

Accepted Answer

A) AB and aB 
B) ab and Ab 
C) AB and Ab 
D) aB and Ab 
A) AB and aB 
B) ab and Ab 
C) AB and Ab 
D) aB and Ab

Question 18

DNA helicase has an essential role in DNA replication, but its unwinding activity also creates problems ahead of the replication fork, requiring the function of another class of enzymes.Describe the problem caused by DNA helicase, name the enzymes that resolve the problem, and explain the mechanism of resolution.

Accepted Answer

As DNA helicase unwinds DNA strands to m

Question 19

You have discovered an "Exo-" mutant form of DNA polymerase in which the 3′-to-5′ exonuclease function has been destroyed but the ability to join nucleotides together is unchanged.Which of the following properties do you expect the mutant polymerase to have?

Accepted Answer

A) It will polymerize in both the 5′-to-3′ direction and the 3′-to-5′ direction. 
B) It will polymerize more slowly than the normal Exo+ polymerase. 
C) It will fall off the template more frequently than the normal Exo+ polymerase. 
D) It will be more likely to generate mismatched base pairs. 
A) It will polymerize in both the 5′-to-3′ direction and the 3′-to-5′ direction. 
B) It will polymerize more slowly than the normal Exo+ polymerase. 
C) It will fall off the template more frequently than the normal Exo+ polymerase. 
D) It will be more likely to generate mismatched base pairs.

Question 20

Sometimes, chemical damage to DNA can occur just before DNA replication begins, not giving the repair system enough time to correct the error before the DNA is duplicated.This gives rise to mutation.If the adenosine in the sequence TCAT is depurinated and not repaired, which of the following is the point mutation that you would observe after this segment has undergone two rounds of DNA replication?

Accepted Answer

A) TCGT 
B) TAT 
C) TCT 
D) TGTT 
A) TCGT 
B) TAT 
C) TCT 
D) TGTT

Which of the following statements about the newly synthesized strand of a human chromosome is TRUE?

Several members of the same family were diagnosed with the same kind of cancer when they were unusually young.Which one of the following is the most likely explanation for this phenomenon? It is possible that the individuals with the cancer have inherited

In terms of its function, is telomerase more like DNA polymerase or Primase? Explain your reasoning.

Telomeres serve as caps protecting the ends of linear chromosomes.Which of the following is FALSE regarding the replication of telomeric sequences?

In somatic cells, if a base is mismatched in one new daughter strand during DNA replication, and is not repaired, what fraction of the DNA duplexes will have a permanent change in the DNA sequence after the second round of DNA replication?

How many replication forks are formed when an origin of replication is opened?

Beside the distortion in the DNA backbone caused by a mismatched base pair, what additional mark is there on eukaryotic DNA to indicate which strand needs to be repaired?

Which diagram accurately represents the directionality of DNA strands at one side of a replication fork? (a) (b) (c) (d) Figure 6-19

The process of DNA replication requires that each of the parental DNA strands be used as a __________ to produce a duplicate of the opposing strand.

DNA polymerases are processive, which means that they remain tightly associated with the template strand while moving rapidly and adding nucleotides to the growing daughter strand.Which piece of the replication machinery accounts for this characteristic?

A mismatched base pair causes a distortion in the DNA backbone.If this were the only indication of an error in replication, the overall rate of mutation would be much higher.Explain why.

How does the total number of replication origins in bacterial cells compare to the number of origins in human cells?

DNA replication is considered semiconservative because

You have discovered an "Exo^-" mutant form of DNA polymerase in which the 3′-to-5′ exonuclease function has been destroyed but the ability to join nucleotides together is unchanged.Which of the following properties do you expect the mutant polymerase to have?

Cells: The Fundamental Units of Life

Chemical Components of Cells

Energy, Catalysis, and Biosynthesis

Protein Structure and Function

DNA and Chromosomes

From DNA to Protein

Control of Gene Expression

How Genes and Genomes Evolve

Analyzing the Structure and Function of Genes

Membrane Structure

Transport Across Cell Membranes

How Cells Obtain Energy From Food

Energy Generation in Mitochondria and Chloroplasts

Intracellular Compartments and Protein Transport

Cell Signaling

Cytoskeleton

The Cell-Division Cycle

Sexual Reproduction and the Power of Genetics

Cell Communities: Tissues, Stem Cells, and Cancer

Filters

Exam 6: DNA Replication and Repair

Which of the following statements about the newly synthesized strand of a human chromosome is TRUE?

Several members of the same family were diagnosed with the same kind of cancer when they were unusually young.Which one of the following is the most likely explanation for this phenomenon? It is possible that the individuals with the cancer have inherited

In terms of its function, is telomerase more like DNA polymerase or Primase? Explain your reasoning.

Telomeres serve as caps protecting the ends of linear chromosomes.Which of the following is FALSE regarding the replication of telomeric sequences?

In somatic cells, if a base is mismatched in one new daughter strand during DNA replication, and is not repaired, what fraction of the DNA duplexes will have a permanent change in the DNA sequence after the second round of DNA replication?

How many replication forks are formed when an origin of replication is opened?

Beside the distortion in the DNA backbone caused by a mismatched base pair, what additional mark is there on eukaryotic DNA to indicate which strand needs to be repaired?

Which diagram accurately represents the directionality of DNA strands at one side of a replication fork? (a) (b) (c) (d) Figure 6-19

The process of DNA replication requires that each of the parental DNA strands be used as a __________ to produce a duplicate of the opposing strand.

DNA polymerases are processive, which means that they remain tightly associated with the template strand while moving rapidly and adding nucleotides to the growing daughter strand.Which piece of the replication machinery accounts for this characteristic?

A mismatched base pair causes a distortion in the DNA backbone.If this were the only indication of an error in replication, the overall rate of mutation would be much higher.Explain why.

How does the total number of replication origins in bacterial cells compare to the number of origins in human cells?

DNA replication is considered semiconservative because

You have discovered an "Exo-" mutant form of DNA polymerase in which the 3′-to-5′ exonuclease function has been destroyed but the ability to join nucleotides together is unchanged.Which of the following properties do you expect the mutant polymerase to have?

Cells: The Fundamental Units of Life

Chemical Components of Cells

Energy, Catalysis, and Biosynthesis

Protein Structure and Function

DNA and Chromosomes

From DNA to Protein

Control of Gene Expression

How Genes and Genomes Evolve

Analyzing the Structure and Function of Genes

Membrane Structure

Transport Across Cell Membranes

How Cells Obtain Energy From Food

Energy Generation in Mitochondria and Chloroplasts

Intracellular Compartments and Protein Transport

Cell Signaling

Cytoskeleton

The Cell-Division Cycle

Sexual Reproduction and the Power of Genetics

Cell Communities: Tissues, Stem Cells, and Cancer

Filters

You have discovered an "Exo^-" mutant form of DNA polymerase in which the 3′-to-5′ exonuclease function has been destroyed but the ability to join nucleotides together is unchanged.Which of the following properties do you expect the mutant polymerase to have?