Question 1

Researchers found E.coli that had mutation rates 100 times higher than normal.What is a possible explanation for these results?

Accepted Answer

A) The single-stranded binding proteins were malfunctioning. 
B) There were one or more mismatches in the RNA primer. 
C) The proofreading mechanism of DNA polymerase was not working properly. 
D) The DNA polymerase was unable to add bases to the 3′ end of the growing nucleic acid chain. 
A) The single-stranded binding proteins were malfunctioning. 
B) There were one or more mismatches in the RNA primer. 
C) The proofreading mechanism of DNA polymerase was not working properly. 
D) The DNA polymerase was unable to add bases to the 3′ end of the growing nucleic acid chain.

Question 2

In humans,xeroderma pigmentosum is a disorder of the nucleotide excision repair mechanism.These individuals are unable to repair DNA damage caused by ultraviolet light.Which of the following are the most prominent types of mutations in individuals suffering from xeroderma pigmentosum?

Accepted Answer

A) mismatch errors 
B) telomere shortening 
C) methylation of purines 
D) pyrimidine dimers 
A) mismatch errors 
B) telomere shortening 
C) methylation of purines 
D) pyrimidine dimers

Question 3

DNA contains the template needed to copy itself,but as you learned in Chapter 4,it has no catalytic activity.What catalyzes the formation of phosphodiester bonds between adjacent nucleotides in the DNA polymer being formed?

Accepted Answer

A) ribozymes 
B) DNA polymerase 
C) ATP 
D) deoxyribonucleotide triphosphates 
A) ribozymes 
B) DNA polymerase 
C) ATP 
D) deoxyribonucleotide triphosphates

Question 4

DNA replication is highly accurate.It results in about one mistake per billion nucleotides.For the human genome,how often would errors occur?

Accepted Answer

A) on average,once or twice in the lifetime of an individual 
B) on average,6 times each time the entire genome of a cell is replicated 
C) on average,once every 6 cell divisions 
D) on average,once a lifetime in 10% of the population 
A) on average,once or twice in the lifetime of an individual 
B) on average,6 times each time the entire genome of a cell is replicated 
C) on average,once every 6 cell divisions 
D) on average,once a lifetime in 10% of the population

Question 5

Put the following steps of DNA replication in chronological order. 1. Single-stranded binding proteins attach to DNA strands.
2) Hydrogen bonds between base pairs of antiparallel strands are broken.
3) Primase binds to the site of origin.
4) DNA polymerase binds to the template strand.
5) An RNA primer is created.

Accepted Answer

A) 1,2,3,4,5 
B) 2,1,3,5,4 
C) 3,2,1,5,4 
D) 1,2,3,4,4 
A) 1,2,3,4,5 
B) 2,1,3,5,4 
C) 3,2,1,5,4 
D) 1,2,3,4,4

Question 6

If during the process of DNA replication,the enzyme topoisomerase was not functioning (i.e.it was mutated)what do you expect will happen to the replication process?

Accepted Answer

A) The double helix would not begin to unwind at all. 
B) The double helix would begin to unwind but this unwinding would stop prematurely due to over-twisting of the DNA. 
C) The double helix would unwind completely but no primers would be added to the template strand. 
D) The double helix would unwind completely but no new strand would be created due to the formation of secondary structures. 
A) The double helix would not begin to unwind at all. 
B) The double helix would begin to unwind but this unwinding would stop prematurely due to over-twisting of the DNA. 
C) The double helix would unwind completely but no primers would be added to the template strand. 
D) The double helix would unwind completely but no new strand would be created due to the formation of secondary structures.

Question 7

What is a telomere?

Accepted Answer

A) the mechanism that holds two sister chromatids together 
B) the reorganization of the cell nucleus that takes place during telophase 
C) the site of origin of DNA replication 
D) the ends of linear chromosomes 
A) the mechanism that holds two sister chromatids together 
B) the reorganization of the cell nucleus that takes place during telophase 
C) the site of origin of DNA replication 
D) the ends of linear chromosomes

Question 8

Recent studies have shown that xeroderma pigmentosum (an error in the nucleotide excision repair process)can result from mutations in one of seven genes.What can you infer from this finding?

Accepted Answer

A) There are seven genes that produce the same protein. 
B) These seven genes are the most easily damaged by ultraviolet light. 
C) There are several enzymes involved in the nucleotide excision repair process. 
D) These mutations have resulted from translocation of gene segments. 
A) There are seven genes that produce the same protein. 
B) These seven genes are the most easily damaged by ultraviolet light. 
C) There are several enzymes involved in the nucleotide excision repair process. 
D) These mutations have resulted from translocation of gene segments.

Question 9

What can you infer from the information presented in this table?

Accepted Answer

A) DNA polymerase I and DNA polymerase III are the same enzyme found in different organisms. 
B) DNA polymerase I and DNA polymerase III have different functions. 
C) The sliding clamp molecule is a ribozyme. 
D) Topoisomerase is involved in proofreading activity. 
A) DNA polymerase I and DNA polymerase III are the same enzyme found in different organisms. 
B) DNA polymerase I and DNA polymerase III have different functions. 
C) The sliding clamp molecule is a ribozyme. 
D) Topoisomerase is involved in proofreading activity.

Question 10

Figure 14.3  
-Refer to Figure 14.3.Which structure is responsible for stabilizing DNA in its single-stranded form?

Accepted Answer

The answer of Figure 14.3  
-Refer to Figure 14.3.Which...

Question 11

Hereditary nonpolyposis colorectal cancer (HNPCC)is an inherited disorder.The genetic defect identified is an error in the mismatch repair mechanism.Which of the following would be an expected result of this mutation?

Accepted Answer

A) increased rate of errors by wild-type DNA polymerase 
B) increased rate of formation of pyrimidine dimers 
C) increased rate of repair of pyrimidine dimers 
D) decreased ability to repair certain DNA mutations 
A) increased rate of errors by wild-type DNA polymerase 
B) increased rate of formation of pyrimidine dimers 
C) increased rate of repair of pyrimidine dimers 
D) decreased ability to repair certain DNA mutations

Question 12

If DNA repair mechanisms fail,what is the result?

Accepted Answer

A) a mutation 
B) a defective enzyme 
C) cancer 
D) All of the above can result from the failure of DNA repair mechanisms. 
A) a mutation 
B) a defective enzyme 
C) cancer 
D) All of the above can result from the failure of DNA repair mechanisms.

Question 13

In a healthy cell,the rate of DNA repair is equal to the rate of DNA mutation.When the rate of repair lags behind the rate of mutation,what is a possible fate of the cell?

Accepted Answer

A) The cell can be transformed to a cancerous cell. 
B) The cell differentiates to form a different,but vital tissue. 
C) The process of differentiation of cells that takes place in embryonic development is dependent on a higher rate of DNA mutation than the rate of DNA repair. 
D) DNA synthesis will continue in an attempt to repair itself. 
A) The cell can be transformed to a cancerous cell. 
B) The cell differentiates to form a different,but vital tissue. 
C) The process of differentiation of cells that takes place in embryonic development is dependent on a higher rate of DNA mutation than the rate of DNA repair. 
D) DNA synthesis will continue in an attempt to repair itself.

Question 14

Which of the following would be least likely to cause DNA damage in an individual suffering from xeroderma pigmentosum?

Accepted Answer

A) natural lighting 
B) low-level ultraviolet lights 
C) incandescent light bulbs 
D) reflected sunlight 
A) natural lighting 
B) low-level ultraviolet lights 
C) incandescent light bulbs 
D) reflected sunlight

Question 15

Figure 14.2  
-Identify the lagging strand in Figure 14.2.

Accepted Answer

A) a 
B) b 
C) c 
D) d 
A) a 
B) b 
C) c 
D) d

Question 16

What is the difference between the leading strand and the lagging strand in DNA replication?

Accepted Answer

A) The leading strand is synthesized in the 3′→5′ direction in a discontinuous fashion,while the lagging strand is synthesized in the 5′→3′ direction in a continuous fashion. 
B) The leading strand requires an RNA primer,whereas the lagging strand does not. 
C) The leading strand is synthesized continuously in the 5′→3′ direction,while the lagging strand is synthesized discontinuously in the 5′→3′ direction. 
D) There are different DNA polymerases involved in elongation of the leading strand and the lagging strand. 
A) The leading strand is synthesized in the 3′→5′ direction in a discontinuous fashion,while the lagging strand is synthesized in the 5′→3′ direction in a continuous fashion. 
B) The leading strand requires an RNA primer,whereas the lagging strand does not. 
C) The leading strand is synthesized continuously in the 5′→3′ direction,while the lagging strand is synthesized discontinuously in the 5′→3′ direction. 
D) There are different DNA polymerases involved in elongation of the leading strand and the lagging strand.

Question 17

In the polymerization of DNA,a phosphodiester bond is formed between a phosphate group of the nucleotide being added and ________ of the last nucleotide in the polymer.

Accepted Answer

A) ATP 
B) C₆ 
C) the 3′ OH 
D) a nitrogen from the nitrogen-containing base 
A) ATP 
B) C₆ 
C) the 3′ OH 
D) a nitrogen from the nitrogen-containing base

Question 18

The epsilon (ε)subunit of DNA polymerase III of E.coli has exonuclease activity.How does it function in the proofreading process?

Accepted Answer

A) The epsilon subunit can remove a mismatched nucleotide. 
B) The epsilon subunit excises a segment of DNA around the mismatched base. 
C) The epsilon subunit can recognize which strand is the template or parent strand,and which is the new strand of DNA. 
D) It adds nucleotide triphosphates to the 3′ end of the growing DNA strand. 
A) The epsilon subunit can remove a mismatched nucleotide. 
B) The epsilon subunit excises a segment of DNA around the mismatched base. 
C) The epsilon subunit can recognize which strand is the template or parent strand,and which is the new strand of DNA. 
D) It adds nucleotide triphosphates to the 3′ end of the growing DNA strand.

Question 19

Semiconservative replication involves a template.What is the template?

Accepted Answer

A) single-stranded binding proteins 
B) DNA polymerase contains the template needed 
C) one strand of the DNA molecule 
D) an RNA molecule 
A) single-stranded binding proteins 
B) DNA polymerase contains the template needed 
C) one strand of the DNA molecule 
D) an RNA molecule

Exam 14: Dna and the Gene: Synthesis and Repair

Researchers found E.coli that had mutation rates 100 times higher than normal.What is a possible explanation for these results?

In humans,xeroderma pigmentosum is a disorder of the nucleotide excision repair mechanism.These individuals are unable to repair DNA damage caused by ultraviolet light.Which of the following are the most prominent types of mutations in individuals suffering from xeroderma pigmentosum?

DNA contains the template needed to copy itself,but as you learned in Chapter 4,it has no catalytic activity.What catalyzes the formation of phosphodiester bonds between adjacent nucleotides in the DNA polymer being formed?

DNA replication is highly accurate.It results in about one mistake per billion nucleotides.For the human genome,how often would errors occur?

If during the process of DNA replication,the enzyme topoisomerase was not functioning (i.e.it was mutated)what do you expect will happen to the replication process?

What is a telomere?

Recent studies have shown that xeroderma pigmentosum (an error in the nucleotide excision repair process)can result from mutations in one of seven genes.What can you infer from this finding?

What can you infer from the information presented in this table?

Figure 14.3 -Refer to Figure 14.3.Which structure is responsible for stabilizing DNA in its single-stranded form?

Hereditary nonpolyposis colorectal cancer (HNPCC)is an inherited disorder.The genetic defect identified is an error in the mismatch repair mechanism.Which of the following would be an expected result of this mutation?

If DNA repair mechanisms fail,what is the result?

In a healthy cell,the rate of DNA repair is equal to the rate of DNA mutation.When the rate of repair lags behind the rate of mutation,what is a possible fate of the cell?

Which of the following would be least likely to cause DNA damage in an individual suffering from xeroderma pigmentosum?

Figure 14.2 -Identify the lagging strand in Figure 14.2.

What is the difference between the leading strand and the lagging strand in DNA replication?

In the polymerization of DNA,a phosphodiester bond is formed between a phosphate group of the nucleotide being added and ________ of the last nucleotide in the polymer.

The epsilon (ε)subunit of DNA polymerase III of E.coli has exonuclease activity.How does it function in the proofreading process?

Semiconservative replication involves a template.What is the template?

Biology and the Tree of Life

Water and Carbon: the Chemical Basis of Life

Protein Structure and Function

Nucleic Acids and the Rna World

An Introduction to Carbohydrates

Lipids, membranes, and the First Cells

Inside the Cell

Cell-Cell Interactions

Cellular Respiration and Fermentation

Photosynthesis

The Cell Cycle

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Mendel and the Gene

How Genes Work

Transcription, RNA Processing, and Translation

Control of Gene Expression in Bacteria

Control of Gene Expression in Eukaryotes

Analyzing and Engineering Genes

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Principles of Development

An Introduction to Animal Development

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Evolution by Natural Selection

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Electrical Signals in Animals

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