Question 1

What type of topoisomerase can introduce supercoils?

Accepted Answer

A)  type I 
B)  type II 
C)  type III 
D)  type IV 
E)  All topoisomerase can introduce supercoils. 
A)  type I 
B)  type II 
C)  type III 
D)  type IV 
E)  All topoisomerase can introduce supercoils.

Question 2

How can the leading and lagging strands be synthesized in a coordinated fashion?

Accepted Answer

A)  Specific enzymes control the size of the DNA opening. 
B)  Lagging-strand binding proteins inhibit leading-strand replication if the strands become disproportionate in size. 
C)  DNA polymerase III is a dimeric holoenzyme, and the looped lagging strand allows the enzyme to proceed in the same direction with each strand. 
D)  Leading and lagging strand syntheses are catalyzed by two distinct and noninteracting replisomes, but the rate is controlled by helicase. 
E)  None of the answers is correct. 
A)  Specific enzymes control the size of the DNA opening. 
B)  Lagging-strand binding proteins inhibit leading-strand replication if the strands become disproportionate in size. 
C)  DNA polymerase III is a dimeric holoenzyme, and the looped lagging strand allows the enzyme to proceed in the same direction with each strand. 
D)  Leading and lagging strand syntheses are catalyzed by two distinct and noninteracting replisomes, but the rate is controlled by helicase. 
E)  None of the answers is correct.

Question 3

DNA serves as the _____ for synthesis of complementary strands of DNA.

Accepted Answer

A)  primer 
B)  catalyst 
C)  template 
D)  primer and template 
E)  None of the answers is correct. 
A)  primer 
B)  catalyst 
C)  template 
D)  primer and template 
E)  None of the answers is correct.

Question 4

What is a Klenow fragment?

Accepted Answer

The first DNA polymerase structure was d

Question 5

What is a processive polymerase enzyme versus a distributive enzyme?

Accepted Answer

Processive enzymes catalyze mu

Question 6

How is replication specificity dictated?

Accepted Answer

A)  Proper base-pairing is dictated more by shape than by hydrogen bonding capacity. 
B)  Enzyme interactions with the DNA act as a "ruler" to determine if the properly spaced base pair has been formed. 
C)  The bond is broken and reformed to ensure its accurate placement at each base pair. 
D)  All the answers are correct. 
E)  A and B are both correct. 
A)  Proper base-pairing is dictated more by shape than by hydrogen bonding capacity. 
B)  Enzyme interactions with the DNA act as a "ruler" to determine if the properly spaced base pair has been formed. 
C)  The bond is broken and reformed to ensure its accurate placement at each base pair. 
D)  All the answers are correct. 
E)  A and B are both correct.

Question 7

One metal ion in the DNA polymerase reaction coordinates the 3'-hydroxyl group of the primer, and the second metal ion interacts with the ______________.

Accepted Answer

The answer of One metal ion in the DNA polymerase...

Question 8

Why is shape complementarity so important in DNA replication?

Accepted Answer

Residues of the polymerase enzyme form h

Question 9

Why is thymine instead of uracil used in DNA?

Accepted Answer

The methyl group on thymine allows it to

Question 10

DNA polymerase III is able to correct mistakes in replication due to its _________________ function.

Accepted Answer

The answer of DNA polymerase III is able to correct...

Question 11

What is true about DNA polymerases?

Accepted Answer

A)  There are at least five structural classes. 
B)  All have finger and thumb domains that wrap around the DNA. 
C)  All catalyze the same reaction, which requires metal cofactors. 
D)  All the answers are correct. 
E)  There are five structural classes, and all catalyze the same reaction, which requires metal cofactors. 
A)  There are at least five structural classes. 
B)  All have finger and thumb domains that wrap around the DNA. 
C)  All catalyze the same reaction, which requires metal cofactors. 
D)  All the answers are correct. 
E)  There are five structural classes, and all catalyze the same reaction, which requires metal cofactors.

Question 12

Topoisomerases are enzymes that introduce or eliminate supercoils in DNA during replication. What is the difference in mechanism and energy requirements for topoisomerase types I and II?

Accepted Answer

Type I topoisomerases catalyze the therm

Question 13

One function of the two metal cations that are required by DNA polymerases is

Accepted Answer

A)  to stabilize the negative charge of the transition state. 
B)  to bind ATP. 
C)  to complex with a Tyr residue in the active site. 
D)  to cleave improperly matched bases 
E)  None of the answers is correct. 
A)  to stabilize the negative charge of the transition state. 
B)  to bind ATP. 
C)  to complex with a Tyr residue in the active site. 
D)  to cleave improperly matched bases 
E)  None of the answers is correct.

Question 14

UV light causes damage to DNA by forming __________________.

Accepted Answer

The answer of UV light causes damage to DNA by...

Question 15

Type ________ topoisomerase introduces negative supercoils in DNA while type ________ topoisomerase relaxes supercoil structures.

Accepted Answer

The answer of Type ________ topoisomerase introduces negative supercoils in...

Question 16

What is the formula for the linking number?

Accepted Answer

A)  Lk = Wr − Tw 
B)  Lk = Wr + Tw 
C)  Tw = Wr + Lk 
D)  Lk = Tw/Wr 
E)  None of the answers is correct. 
A)  Lk = Wr − Tw 
B)  Lk = Wr + Tw 
C)  Tw = Wr + Lk 
D)  Lk = Tw/Wr 
E)  None of the answers is correct.

Question 17

The human genetic skin disease caused by a mutation in components of the human nucleotide-excision-repair pathway is called ___________________.

Accepted Answer

xeroderma

Question 18

How are DNA strand breaks sealed?

Accepted Answer

DNA ligase is the enzyme that seals the

Question 19

What describes the number of times a DNA strand winds around the helix axis when the axis lies in a plane?

Accepted Answer

A)  linking number 
B)  writhe number 
C)  twist number 
D)  supercoil number 
E)  None of the answers is correct. 
A)  linking number 
B)  writhe number 
C)  twist number 
D)  supercoil number 
E)  None of the answers is correct.

Question 20

What structure is found at the ends of chromosomes?

Accepted Answer

A)  origin of replication 
B)  consensus sequence 
C)  Holliday junction 
D)  telomere 
E)  None of the answers is correct. 
A)  origin of replication 
B)  consensus sequence 
C)  Holliday junction 
D)  telomere 
E)  None of the answers is correct.

Exam 28: DNA Replication, Repair, and Recombination

What type of topoisomerase can introduce supercoils?

How can the leading and lagging strands be synthesized in a coordinated fashion?

DNA serves as the _____ for synthesis of complementary strands of DNA.

What is a Klenow fragment?

What is a processive polymerase enzyme versus a distributive enzyme?

How is replication specificity dictated?

One metal ion in the DNA polymerase reaction coordinates the 3'-hydroxyl group of the primer, and the second metal ion interacts with the ______________.

Why is shape complementarity so important in DNA replication?

Why is thymine instead of uracil used in DNA?

DNA polymerase III is able to correct mistakes in replication due to its _________________ function.

What is true about DNA polymerases?

Topoisomerases are enzymes that introduce or eliminate supercoils in DNA during replication. What is the difference in mechanism and energy requirements for topoisomerase types I and II?

One function of the two metal cations that are required by DNA polymerases is

UV light causes damage to DNA by forming __________________.

Type ________ topoisomerase introduces negative supercoils in DNA while type ________ topoisomerase relaxes supercoil structures.

What is the formula for the linking number?

The human genetic skin disease caused by a mutation in components of the human nucleotide-excision-repair pathway is called ___________________.

How are DNA strand breaks sealed?

What describes the number of times a DNA strand winds around the helix axis when the axis lies in a plane?

What structure is found at the ends of chromosomes?

Biochemistry: an Evolving Science

Protein Composition and Structure

Exploring Proteins and Proteomes

DNA, RNA, and the Flow of Genetic Information

Exploring Genes and Genomes

Exploring Evolution and Bioinformatics

Hemoglobin: a Portrait of a Protein in Action

Enzymes: Basic Concepts and Kinetics

Oxidative Phosphorylation

Catalytic Strategies

Regulatory Strategies

Carbohydrates

Lipids and Cell Membranes

Membrane Channels and Pumps

Signal-Transduction Pathways

Metabolism: Basic Concepts and Design

Glycolysis and Gluconeogenesis

The Citric Acid Cycle

The Light Reactions of Photosynthesis

The Calvin Cycle and the Pentose Phosphate Pathway

Glycogen Metabolism

Fatty Acid Metabolism

Protein Turnover and Amino Acid Catabolism

The Biosynthesis of Amino Acids

Nucleotide Biosynthesis

Biosynthesis of Membrane Lipids and Steroids

The Integration of Metabolism

Rna Synthesis and Processing

Protein Synthesis

The Control of Gene Expression in Prokaryotes

The Control of Gene Expression in Eukaryotes

Sensory Systems

The Immune System

Molecular Motors

Drug Development

Filters

Type topoisomerase introduces negative supercoils in DNA while type topoisomerase relaxes supercoil structures.