Question 1

Which feature is NOT applicable to homologous recombination during meiosis?

Accepted Answer

A)  a double strand break 
B)  cleavage of two crossover events 
C)  alignment of homologous chromosomes 
D)  formation of a single Holliday intermediate 
E)  exposed 3ʹ ends invade the intact duplex DNA of the homolog 
A)  a double strand break 
B)  cleavage of two crossover events 
C)  alignment of homologous chromosomes 
D)  formation of a single Holliday intermediate 
E)  exposed 3ʹ ends invade the intact duplex DNA of the homolog

Question 2

Which compound is NOT required for initiation of DNA replication in E. coli?

Accepted Answer

A)  DnaB (helicase) 
B)  DnaG (primase) 
C)  Dam methylase 
D)  DNA ligase 
E)  DnaA (a AAA+ ATPase) 
A)  DnaB (helicase) 
B)  DnaG (primase) 
C)  Dam methylase 
D)  DNA ligase 
E)  DnaA (a AAA+ ATPase)

Question 3

The RNA primase in the E. coli Pol III replisome is one of the most highly error-prone polymerases known. Explain why this does not affect the accuracy of DNA replication in E. coli.

Accepted Answer

RNA primase is an enzyme that synthesize

Question 4

How many rounds of replication would result in a 1:1 distribution of hybrid to new DNA helices in the Meselson and Stahl experiment?

Accepted Answer

A)  one 
B)  two 
C)  three 
D)  four 
E)  five 
A)  one 
B)  two 
C)  three 
D)  four 
E)  five

Question 5

When a DNA molecule is described as replicating bidirectionally, that means that it has two:

Accepted Answer

A)  chains. 
B)  independently replicating segment. 
C)  origins. 
D)  replication forks. 
E)  termination points. 
A)  chains. 
B)  independently replicating segment. 
C)  origins. 
D)  replication forks. 
E)  termination points.

Question 6

Match the damage type or repair step at the left with a related enzyme at right. Only one answer will be the most direct for each.

Accepted Answer

To match the damage type or repair step

Question 7

Which statement does NOT describe a feature of site-specific recombination?

Accepted Answer

A)  A specific recombinase enzyme is required. 
B)  The energy of the phosphodiester bond is preserved in covalent enzyme-DNA linkage. 
C)  Recombination sites have non-palindromic sequences. 
D)  Formation of Holliday intermediates is required. 
E)  Insertions or deletions can result from site-specific recombination. 
A)  A specific recombinase enzyme is required. 
B)  The energy of the phosphodiester bond is preserved in covalent enzyme-DNA linkage. 
C)  Recombination sites have non-palindromic sequences. 
D)  Formation of Holliday intermediates is required. 
E)  Insertions or deletions can result from site-specific recombination.

Question 8

Explain the role of DNA glycosylases in DNA repair.

Accepted Answer

DNA glycosylases are enzymes that play a

Question 9

It is possible to mutate E. coli DNA Pol I so that it no longer has any exonuclease activity. What would be a potential result of this change?

Accepted Answer

A)  The enzyme would become more processive. 
B)  The enzyme would be more error prone. 
C)  The enzyme would become more efficient in base excision repair. 
D)  The enzyme would become more processive and more error-prone. 
E)  None of these is a potential outcome. 
A)  The enzyme would become more processive. 
B)  The enzyme would be more error prone. 
C)  The enzyme would become more efficient in base excision repair. 
D)  The enzyme would become more processive and more error-prone. 
E)  None of these is a potential outcome.

Question 10

In contrast to bacteria, eukaryotic chromosomes need multiple DNA replication origins because:

Accepted Answer

A)  eukaryotic chromosomes cannot usually replicate bidirectionally. 
B)  eukaryotic genomes are not usually circular, like the bacterial chromosome is. 
C)  the processivity of the eukaryotic DNA polymerase is much less than the bacterial enzyme. 
D)  their replication rate is much slower, and it would take too long with only a single origin per chromosome. 
E)  they have a variety of DNA polymerases for different purposes, and need a corresponding variety of replication origins. 
A)  eukaryotic chromosomes cannot usually replicate bidirectionally. 
B)  eukaryotic genomes are not usually circular, like the bacterial chromosome is. 
C)  the processivity of the eukaryotic DNA polymerase is much less than the bacterial enzyme. 
D)  their replication rate is much slower, and it would take too long with only a single origin per chromosome. 
E)  they have a variety of DNA polymerases for different purposes, and need a corresponding variety of replication origins.

Question 11

In the Ames test, the clear region of no growth near the center of the plate (where the compound of interest is placed) typically indicates that the compound is:

Accepted Answer

A)  not mutagenic. 
B)  an antibiotic. 
C)  an amino acid. 
D)  lethal at high enough concentrations. 
E)  not taken up by bacteria. 
A)  not mutagenic. 
B)  an antibiotic. 
C)  an amino acid. 
D)  lethal at high enough concentrations. 
E)  not taken up by bacteria.

Question 12

In the bacterial cell, what are catenated chromosomes, when do they arise, and how does the cell resolve the problem posed by their structure?

Accepted Answer

Catenated chromosomes in a bacterial cel

Question 13

Which statement is TRUE regarding the process catalyzed by the bacteriophage $\lambda$ integrase?

Accepted Answer

A)  Serines in the protein active site become covalently attached to the nucleic acids during the mechanism. 
B)  The reaction is an ATP-dependent process. 
C)  The reaction steps are successive tranesterifications. 
D)  The integrase can be classified as a hydrolase. 
E)  The target DNA sequence for this protein is nonspecific. 
A)  Serines in the protein active site become covalently attached to the nucleic acids during the mechanism. 
B)  The reaction is an ATP-dependent process. 
C)  The reaction steps are successive tranesterifications. 
D)  The integrase can be classified as a hydrolase. 
E)  The target DNA sequence for this protein is nonspecific.

Question 14

All known DNA polymerases catalyze synthesis only in the 5' $\rightarrow$  3' direction. Nevertheless, during semiconservative DNA replication in the cell, they are able to catalyze the synthesis of both daughter chains, which would appear to require synthesis in the 3' $\rightarrow$  5' direction. Explain the process that occurs in the cell that allows for synthesis of both daughter chains by DNA polymerase.

Accepted Answer

DNA replication is a semiconservative pr

Question 15

In a mammalian cell, DNA repair systems:

Accepted Answer

A)  are extraordinarily efficient energetically. 
B)  are generally absent, except in egg and sperm cells. 
C)  can repair deletions, but not mismatches. 
D)  can repair most types of lesions except those caused by UV light. 
E)  normally repair more than 99% of the DNA lesions that occur. 
A)  are extraordinarily efficient energetically. 
B)  are generally absent, except in egg and sperm cells. 
C)  can repair deletions, but not mismatches. 
D)  can repair most types of lesions except those caused by UV light. 
E)  normally repair more than 99% of the DNA lesions that occur.

Question 16

DNA replication in E. coli:

Accepted Answer

A)  of the leading strand requires multiple primers. 
B)  is mostly 3'to 5'. 
C)  always finishes at a conserved terminator sequence. 
D)  requires DNA-dependent RNA synthesis. 
E)  does not require the action of topoisomerases. 
A)  of the leading strand requires multiple primers. 
B)  is mostly 3'to 5'. 
C)  always finishes at a conserved terminator sequence. 
D)  requires DNA-dependent RNA synthesis. 
E)  does not require the action of topoisomerases.

Question 17

E. coli DNA polymerase III:

Accepted Answer

A)  can initiate replication without a primer. 
B)  is efficient at nick translation. 
C)  is the principal DNA polymerase in chromosomal DNA replication. 
D)  represents over 90% of the DNA polymerase activity in E. coli cells. 
E)  requires a free 5'-hydroxyl group as a primer. 
A)  can initiate replication without a primer. 
B)  is efficient at nick translation. 
C)  is the principal DNA polymerase in chromosomal DNA replication. 
D)  represents over 90% of the DNA polymerase activity in E. coli cells. 
E)  requires a free 5'-hydroxyl group as a primer.

Question 18

DnaA binds to what sites in the E. coli origin?

Accepted Answer

A)  R sites only 
B)  I sites only 
C)  DUE sites only 
D)  both R and I sites 
E)  both R and DUE sites 
A)  R sites only 
B)  I sites only 
C)  DUE sites only 
D)  both R and I sites 
E)  both R and DUE sites

Question 19

What distinguishes the two mechanistic pathways for transposition in bacteria, and what is a cointegrate?

Accepted Answer

The two mechanistic pathways for transpo

Question 20

Which statement about enzymes that interact with DNA is TRUE?

Accepted Answer

A)  E. coli DNA polymerase I is unusual in that it possesses only a 5' $\rightarrow$3' exonucleolytic activity. 
B)  Endonucleases degrade circular but not linear DNA molecules. 
C)  Exonucleases degrade DNA at a free end. 
D)  Many DNA polymerases have a proofreading 5' $\rightarrow$ 3' exonuclease. 
E)  Primases synthesize a short stretch of DNA to prime further synthesis. 
A)  E. coli DNA polymerase I is unusual in that it possesses only a 5' $\rightarrow$3' exonucleolytic activity. 
B)  Endonucleases degrade circular but not linear DNA molecules. 
C)  Exonucleases degrade DNA at a free end. 
D)  Many DNA polymerases have a proofreading 5' $\rightarrow$ 3' exonuclease. 
E)  Primases synthesize a short stretch of DNA to prime further synthesis.

Exam 25: DNA Metabolism

Which feature is NOT applicable to homologous recombination during meiosis?

Which compound is NOT required for initiation of DNA replication in E. coli?

The RNA primase in the E. coli Pol III replisome is one of the most highly error-prone polymerases known. Explain why this does not affect the accuracy of DNA replication in E. coli.

How many rounds of replication would result in a 1:1 distribution of hybrid to new DNA helices in the Meselson and Stahl experiment?

When a DNA molecule is described as replicating bidirectionally, that means that it has two:

Match the damage type or repair step at the left with a related enzyme at right. Only one answer will be the most direct for each.

Which statement does NOT describe a feature of site-specific recombination?

Explain the role of DNA glycosylases in DNA repair.

It is possible to mutate E. coli DNA Pol I so that it no longer has any exonuclease activity. What would be a potential result of this change?

In contrast to bacteria, eukaryotic chromosomes need multiple DNA replication origins because:

In the Ames test, the clear region of no growth near the center of the plate (where the compound of interest is placed) typically indicates that the compound is:

In the bacterial cell, what are catenated chromosomes, when do they arise, and how does the cell resolve the problem posed by their structure?

Which statement is TRUE regarding the process catalyzed by the bacteriophage λ\lambdaλ integrase?

In a mammalian cell, DNA repair systems:

DNA replication in E. coli:

E. coli DNA polymerase III:

DnaA binds to what sites in the E. coli origin?

What distinguishes the two mechanistic pathways for transposition in bacteria, and what is a cointegrate?

Which statement about enzymes that interact with DNA is TRUE?

The Foundations of Biochemistry

Water

Amino Acids, Peptides, and Proteins

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

DNA-Based Information Technologies

Lipids

Biological Membranes and Transport

Biosignaling

Bioenergetics and Biochemical Reaction Types

Glycolysis, Gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, Nucleotides, and Related Molecules

Hormonal Regulation and Integration of Mammalian Metabolism

Genes and Chromosomes

RNA Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

Which statement is TRUE regarding the process catalyzed by the bacteriophage $\lambda$ integrase?