Question 1

Which of the following statement about eukaryotic DNA replication is INCORRECT?

Accepted Answer

A)  Only one DNA polymerase is required to propagate a replication fork. 
B)  The same polymerase in humans is involved in proofreading and primer removal as well as lagging strand elongation. 
C)  The main DNA polymerase that elongates the leading strand has an intrinsic processivity factor. 
D)  Eukaryotes require two enzymes to remove RNA primers. 
E)  Chromatin must be dismantled in advance of replication forks and reassembled on daughter strands after the fork has passed through. 
A)  Only one DNA polymerase is required to propagate a replication fork. 
B)  The same polymerase in humans is involved in proofreading and primer removal as well as lagging strand elongation. 
C)  The main DNA polymerase that elongates the leading strand has an intrinsic processivity factor. 
D)  Eukaryotes require two enzymes to remove RNA primers. 
E)  Chromatin must be dismantled in advance of replication forks and reassembled on daughter strands after the fork has passed through. A

Question 2

DNA ligase can join Okazaki fragments after activation by ________ of a lysine residue in the active site.

Accepted Answer

adenylation

Question 3

Fidelity of DNA replication is determined solely by the 3' exonucleolytic proofreading activity of the DNA polymerase.

Accepted Answer

A) True 
 B)False  False

Question 4

Replication of linear genomes is problematic because primer removal at the ________ leaves a gap in the duplex.

Accepted Answer

The answer of Replication of linear genomes is problematic because...

Question 5

Which of the following statements about E. coli DNA replication is INCORRECT?

Accepted Answer

A)  The β subunit of DNA polymerase III is the sliding clamp essential for processivity. 
B)  The clamp-loading complex uses exchange between ADP and ATP to eject the clamp loader and close the clamp. 
C)  Single-stranded DNA-binding protein promotes denaturation of DNA by lowering the melting temperature. 
D)  Helicases are multimeric proteins that bind preferentially to one strand and rely on ATP-hydrolysis to unwind the duplex. 
E)  Topoisomerases are responsible for relieving torsional stress ahead of the replication fork generated by unwinding the duplex. 
A)  The β subunit of DNA polymerase III is the sliding clamp essential for processivity. 
B)  The clamp-loading complex uses exchange between ADP and ATP to eject the clamp loader and close the clamp. 
C)  Single-stranded DNA-binding protein promotes denaturation of DNA by lowering the melting temperature. 
D)  Helicases are multimeric proteins that bind preferentially to one strand and rely on ATP-hydrolysis to unwind the duplex. 
E)  Topoisomerases are responsible for relieving torsional stress ahead of the replication fork generated by unwinding the duplex.

Question 6

A single-stranded RNA virus makes a DNA copy of itself by the use of a viral multifunctional enzyme called ________.

Accepted Answer

reverse tr

Question 7

The replicative E. coli DNA polymerase is a symmetrical dimer, with each part of the dimer being responsible for replicating one strand of the DNA duplex.

Accepted Answer

A) True 
 B)False

Question 8

The initiation of DNA replication in E. coli can occur anywhere on the genome that has repeat sequence elements and requires the interaction of DnaA proteins that results in stretching and bending of DNA causing tension that leads to local unwinding.

Accepted Answer

A) True 
 B)False

Question 9

Which of the following is NOT a requirement of E. coli DNA ligase?

Accepted Answer

A)  A nick in the DNA strand must have a 3' OH group. 
B)  A nick in the DNA strand must have a 5' phosphate group. 
C)  The nucleotides being linked must be adjacent in the duplex structure. 
D)  The nucleotides being linked must be properly based-paired. 
E)  ATP 
A)  A nick in the DNA strand must have a 3' OH group. 
B)  A nick in the DNA strand must have a 5' phosphate group. 
C)  The nucleotides being linked must be adjacent in the duplex structure. 
D)  The nucleotides being linked must be properly based-paired. 
E)  ATP

Question 10

DNA gyrase is able to relax supercoils as well as introduce negative supercoils in DNA.

Accepted Answer

A) True 
 B)False

Question 11

E. coli DNA polymerase III makes extensive contacts with the ________ in duplex DNA.

Accepted Answer

The answer of E. coli DNA polymerase III makes extensive...

Question 12

Both type I or type II topoisomerases carry out their catalytic activity via a covalent phosphodiester intermediate between a phosphate group on the DNA and a tyrosine hydroxyl group on the enzyme.

Accepted Answer

A) True 
 B)False

Question 13

Evidence supporting E.coli DNA polymerase III having the major role in nucleotide incorporation during replication includes:

Accepted Answer

A)  DNA polymerase III has a high Vmax. 
B)  There are ten or fewer molecules of enzyme per cell. 
C)  Replication is blocked at high temperatures in temperature sensitive mutants with a thermolabile form of DNA polymerase III. 
D)  A point mutation can inactivate DNA pol III and inhibit replication. 
E)  All of the above. 
A)  DNA polymerase III has a high Vmax. 
B)  There are ten or fewer molecules of enzyme per cell. 
C)  Replication is blocked at high temperatures in temperature sensitive mutants with a thermolabile form of DNA polymerase III. 
D)  A point mutation can inactivate DNA pol III and inhibit replication. 
E)  All of the above.

Question 14

The DNA polymerase reaction is a nucleophilic substitution facilitated by:

Accepted Answer

A)  the 3'OH group being a weak nucleophile. 
B)  the 3'OH group being a strong nucleophile. 
C)  the pyrophosphate being a good leaving group. 
D)  the reaction being irreversible. 
E)  none of the above. 
A)  the 3'OH group being a weak nucleophile. 
B)  the 3'OH group being a strong nucleophile. 
C)  the pyrophosphate being a good leaving group. 
D)  the reaction being irreversible. 
E)  none of the above.

Question 15

A null mutant in the ________ activity of DNA polymerase I will be defective in DNA replication because it will be unable to carry out primer removal.

Accepted Answer

5'-exonucl

Question 16

The specificity of DNA polymerase activity is determined by the shapes of the substrate molecules as well as their ________ capacity.

Accepted Answer

The answer of The specificity of DNA polymerase activity is...

Question 17

Okazaki fragments are initiated with ________ primers by a primase enzyme.

Accepted Answer

RNA, or ri

Question 18

Eukaryotes solve the problem of replicating the ends of their linear chromosomes by:

Accepted Answer

A)  terminal redundancy whereby each end of the chromosome is duplicated allowing recombination. 
B)  using a protein as a primer. 
C)  by covalently linking the two strands at each end of the linear chromosome to form a circle. 
D)  enzyme activity that uses an RNA template and reverse transcription in a series of repeat cycles. 
E)  all of the above. 
A)  terminal redundancy whereby each end of the chromosome is duplicated allowing recombination. 
B)  using a protein as a primer. 
C)  by covalently linking the two strands at each end of the linear chromosome to form a circle. 
D)  enzyme activity that uses an RNA template and reverse transcription in a series of repeat cycles. 
E)  all of the above.

Question 19

The individual proteins of the E. coli replisome complex dissociate and reassociate in a dynamic manner.

Accepted Answer

A) True 
 B)False

Question 20

Which of the following statements about E. coli DNA polymerase I is FALSE?

Accepted Answer

A)  It can copy a circular DNA template but cannot join the ends. 
B)  It can extend a gapped duplex from a 3'OH group and displace a preexisting 5' end. 
C)  The 3' exonuclease site is some distance from the polymerase active site. 
D)  It has 3' exonuclease activity that resides in a small N-terminal fragment that can be cleaved off by limited proteolysis. 
E)  It has 5' exonuclease activity that resides in a small N-terminal fragment that can be cleaved off by limited proteolysis. 
A)  It can copy a circular DNA template but cannot join the ends. 
B)  It can extend a gapped duplex from a 3'OH group and displace a preexisting 5' end. 
C)  The 3' exonuclease site is some distance from the polymerase active site. 
D)  It has 3' exonuclease activity that resides in a small N-terminal fragment that can be cleaved off by limited proteolysis. 
E)  It has 5' exonuclease activity that resides in a small N-terminal fragment that can be cleaved off by limited proteolysis.

Exam 22: DNA Replication

Which of the following statement about eukaryotic DNA replication is INCORRECT?

DNA ligase can join Okazaki fragments after activation by ________ of a lysine residue in the active site.

Fidelity of DNA replication is determined solely by the 3' exonucleolytic proofreading activity of the DNA polymerase.

Replication of linear genomes is problematic because primer removal at the ________ leaves a gap in the duplex.

Which of the following statements about E. coli DNA replication is INCORRECT?

A single-stranded RNA virus makes a DNA copy of itself by the use of a viral multifunctional enzyme called ________.

The replicative E. coli DNA polymerase is a symmetrical dimer, with each part of the dimer being responsible for replicating one strand of the DNA duplex.

The initiation of DNA replication in E. coli can occur anywhere on the genome that has repeat sequence elements and requires the interaction of DnaA proteins that results in stretching and bending of DNA causing tension that leads to local unwinding.

Which of the following is NOT a requirement of E. coli DNA ligase?

DNA gyrase is able to relax supercoils as well as introduce negative supercoils in DNA.

E. coli DNA polymerase III makes extensive contacts with the ________ in duplex DNA.

Both type I or type II topoisomerases carry out their catalytic activity via a covalent phosphodiester intermediate between a phosphate group on the DNA and a tyrosine hydroxyl group on the enzyme.

Evidence supporting E.coli DNA polymerase III having the major role in nucleotide incorporation during replication includes:

The DNA polymerase reaction is a nucleophilic substitution facilitated by:

A null mutant in the ________ activity of DNA polymerase I will be defective in DNA replication because it will be unable to carry out primer removal.

The specificity of DNA polymerase activity is determined by the shapes of the substrate molecules as well as their ________ capacity.

Okazaki fragments are initiated with ________ primers by a primase enzyme.

Eukaryotes solve the problem of replicating the ends of their linear chromosomes by:

The individual proteins of the E. coli replisome complex dissociate and reassociate in a dynamic manner.

Which of the following statements about E. coli DNA polymerase I is FALSE?

Biochemistry and the Language of Chemistry

The Chemical Foundation of Life: Weak Interactions in an Aqueous Environment

The Energetics of Life

Nucleic Acids

Introduction to Proteins: the Primary Level of Protein Structure

The Three-Dimensional Structure of Proteins

Protein Function and Evolution

Enzymes: Biological Catalysts

Carbohydrates: Sugars, Saccharides, Glycans

Lipids, Membranes, and Cellular Transport

Chemical Logic of Metabolism

Carbohydrate Metabolism: Glycolysis, Gluconeogenesis, Glycogen Metabolism, and the Pentose Phosphate Pathway

The Citric Acid Cycle

Electron Transport, Oxidative Phosphorylation, and Oxygen Metabolism

Photosynthesis

Lipid Metabolism

Interorgan and Intracellular Coordination of Energy Metabolism in Vertebrates

Amino Acid and Nitrogen Metabolism

Nucleotide Metabolism

Mechanisms of Signal Transduction

Genes, Genomes, and Chromosomes

DNA Repair, Recombination, and Rearrangement

Transcription and Post-Transcriptional Processing

Information Decoding: Translation and Post-Translational Protein Processing

Regulation of Gene Expression

Filters