Question 1

Replication of DNA must be discontinuous on at least one strand because

Accepted Answer

A)  nicks are required for the unwinding of supercoils. 
B)  the to 5' exonuclease continually introduces nicks in the new DNA. 
C)  the direction of polymerization is always 5' to while the two strands being copied in the replication fork are antiparallel. 
D)  fork movement is bidirectional. 
E)  RNA primers are used. 
A)  nicks are required for the unwinding of supercoils. 
B)  the to 5' exonuclease continually introduces nicks in the new DNA. 
C)  the direction of polymerization is always 5' to while the two strands being copied in the replication fork are antiparallel. 
D)  fork movement is bidirectional. 
E)  RNA primers are used.

Question 2

Eukaryotic chromatin replication:

Accepted Answer

A)  Is facilitated by the presence of a large pool of histones which are synthesized uniformly throughout the cell cycle. 
B)  Is characterized by conservative segregation of pre_existing H3_H4 tetramers at the replication fork. 
C)  Requires the presence of a special enzyme, telomerase, which appends short oligonucleotide blocks to the overhanging S' ends of the newly replicated DNA strands. 
D)  Results in the preferential segregation of the linker histone, H1, to the leading strand. 
E)  Both B and C. 
A)  Is facilitated by the presence of a large pool of histones which are synthesized uniformly throughout the cell cycle. 
B)  Is characterized by conservative segregation of pre_existing H3_H4 tetramers at the replication fork. 
C)  Requires the presence of a special enzyme, telomerase, which appends short oligonucleotide blocks to the overhanging S' ends of the newly replicated DNA strands. 
D)  Results in the preferential segregation of the linker histone, H1, to the leading strand. 
E)  Both B and C.

Question 3

An enzyme which can seal a nick in a DNA duplex is called a

Accepted Answer

A)  sigma factor. 
B)  lipase. 
C)  ligase. 
D)  reverse transcriptase. 
E)  nuclease. 
A)  sigma factor. 
B)  lipase. 
C)  ligase. 
D)  reverse transcriptase. 
E)  nuclease.

Question 4

Synthesis of the leading strand at the replication fork is carried out by

Accepted Answer

A)  DNA polymerase I. 
B)  DNA polymerase III. 
C)  DNA polymerase II. 
D)  RNA polymerase holoenzyme. 
E)  primase. 
A)  DNA polymerase I. 
B)  DNA polymerase III. 
C)  DNA polymerase II. 
D)  RNA polymerase holoenzyme. 
E)  primase.

Question 5

Why is DNA synthesis started with ribonucleotides rather than deoxyribonucleotides?

Accepted Answer

A)  To mark the newly synthesized strand. 
B)  RNA polymerase makes fewer errors when priming than DNA polymerase would. 
C)  DNA polymerases cannot prime. 
D)  To mark the lagging strand for DNA ligase. 
A)  To mark the newly synthesized strand. 
B)  RNA polymerase makes fewer errors when priming than DNA polymerase would. 
C)  DNA polymerases cannot prime. 
D)  To mark the lagging strand for DNA ligase.

Question 6

DNA synthesis requires a primer. A primer is

Accepted Answer

A)  an available serine hydroxyl (-OH) group on DNA polymerase III for initiation of DNA synthesis. 
B)  the complimentary strand of DNA. 
C)  an available 5'-triphosphate on the nitrogenous bases used in synthesis. 
D)  a short oligonucleotide with an available hydroxyl group on the ribose or deoxyribose. 
E)  a short oligonucleotide with an available 2'-hydroxyl group on the ribose or deoxyribose. 
A)  an available serine hydroxyl (-OH) group on DNA polymerase III for initiation of DNA synthesis. 
B)  the complimentary strand of DNA. 
C)  an available 5'-triphosphate on the nitrogenous bases used in synthesis. 
D)  a short oligonucleotide with an available hydroxyl group on the ribose or deoxyribose. 
E)  a short oligonucleotide with an available 2'-hydroxyl group on the ribose or deoxyribose.

Question 7

Which of the following are not required for the enzymatic synthesis of DNA by DNA polymerase I?

Accepted Answer

A)  Mg++ 
B)  a template strand 
C)  ATP 
D)  dTTP 
E)  a primer with a free 3'-OH 
A)  Mg++ 
B)  a template strand 
C)  ATP 
D)  dTTP 
E)  a primer with a free 3'-OH

Question 8

Actinomycin D inhibits the growth of bacteria by

Accepted Answer

A)  specifically inhibiting the initiation of RNA synthesis. 
B)  blocking the further elongation of polypeptide chain synthesis. 
C)  intercalating its phenoxazone ring between two G-C base pairs. 
D)  preventing the binding of aminoacyl-tRNA to the a-site of ribosomes. 
E)  inhibiting the peptidyl transferase activity of ribosomes. 
A)  specifically inhibiting the initiation of RNA synthesis. 
B)  blocking the further elongation of polypeptide chain synthesis. 
C)  intercalating its phenoxazone ring between two G-C base pairs. 
D)  preventing the binding of aminoacyl-tRNA to the a-site of ribosomes. 
E)  inhibiting the peptidyl transferase activity of ribosomes.

Question 9

On the lagging strand, the primer on an Okazaki fragment is removed by the '--->exonuclease activity of DNA polymerase I. What enzyme replaces the degraded primer with deoxyribonucleotides?

Accepted Answer

A)  DNA polymerase III 
B)  DNA ligase + NAD 
C)  terminal transferase 
D)  DNA polymerase I 
E)  DNA gyrase 
A)  DNA polymerase III 
B)  DNA ligase + NAD 
C)  terminal transferase 
D)  DNA polymerase I 
E)  DNA gyrase

Question 10

Frameshift mutations are possible because of

Accepted Answer

A)  redundant (degenerate) code. 
B)  intra-allelic suppressor. 
C)  nonsense codon. 
D)  universality of the code. 
E)  non-overlapping code. 
A)  redundant (degenerate) code. 
B)  intra-allelic suppressor. 
C)  nonsense codon. 
D)  universality of the code. 
E)  non-overlapping code.

Question 11

Concerning the polarity of chain elongation during DNA replication

Accepted Answer

A)  one new strand is elongated in the 5' to direction, while the other strand is polymerized in the to 5' direction. 
B)  both new strands are elongated in the to 5' direction. 
C)  both new strands are elongated in the 5' to direction. 
D)  any one new strand can be elongated in either direction. 
E)  None of the other answers is correct. 
A)  one new strand is elongated in the 5' to direction, while the other strand is polymerized in the to 5' direction. 
B)  both new strands are elongated in the to 5' direction. 
C)  both new strands are elongated in the 5' to direction. 
D)  any one new strand can be elongated in either direction. 
E)  None of the other answers is correct.

Question 12

A mutation in which an A-T base pair in DNA is replaced by a G-C base pair is referred to as a(an) mutation.

Accepted Answer

A)  Transition 
B)  Transversion 
C)  Insertion 
D)  Inversion 
E)  Deletion 
A)  Transition 
B)  Transversion 
C)  Insertion 
D)  Inversion 
E)  Deletion

Question 13

DNA polymerase I catalyzes the reaction of a

Accepted Answer

A)  deoxynucleoside diphosphate with the OH end of a DNA chain. 
B)  deoxynucleoside diphosphate with the 5'-OH end of a DNA chain. 
C)  deoxynucleoside triphosphate with the OH end of a DNA chain. 
D)  deoxynucleoside triphosphate with the 5'-OH end of a DNA chain. 
E)  none of these. 
A)  deoxynucleoside diphosphate with the OH end of a DNA chain. 
B)  deoxynucleoside diphosphate with the 5'-OH end of a DNA chain. 
C)  deoxynucleoside triphosphate with the OH end of a DNA chain. 
D)  deoxynucleoside triphosphate with the 5'-OH end of a DNA chain. 
E)  none of these.

Question 14

Which of the following enzymes is involved in extending the ends of linear chromosomal DNA?

Accepted Answer

A)  telomerase 
B)  ligase 
C)  primase 
D)  RNA polymerase 
E)  DNA polymerase a 
A)  telomerase 
B)  ligase 
C)  primase 
D)  RNA polymerase 
E)  DNA polymerase a

Question 15

Which enzyme activity does DNA Pol I not have?

Accepted Answer

A)  5' to 3' exonuclease 
B)  3' to 5' exonuclease 
C)  5' to 3' DNA polymerase 
D)  3' to 5' DNA polymerase 
A)  5' to 3' exonuclease 
B)  3' to 5' exonuclease 
C)  5' to 3' DNA polymerase 
D)  3' to 5' DNA polymerase

Question 16

Gyrase (topoisomerase II)

Accepted Answer

A)  unwinds double stranded DNA by breaking base pairs 
B)  will increase the writhing number of negatively supercoiled DNA 
C)  will increase the linking number of negatively supercoiled DNA 
D)  nicks one strand of double stranded DNA 
E)  cuts both strands of double stranded DNA 
A)  unwinds double stranded DNA by breaking base pairs 
B)  will increase the writhing number of negatively supercoiled DNA 
C)  will increase the linking number of negatively supercoiled DNA 
D)  nicks one strand of double stranded DNA 
E)  cuts both strands of double stranded DNA

Question 17

High fidelity DNA replication and repair

Accepted Answer

A)  are due to the combined proofreading functions found on DNA polymerase I and III. 
B)  are due to the action of recBCD protein complex. 
C)  are monitored by lexA protein and the SOS response. 
D)  involve the formation of chi form intermediates. 
E)  are solely due to nucleic acid structure. 
A)  are due to the combined proofreading functions found on DNA polymerase I and III. 
B)  are due to the action of recBCD protein complex. 
C)  are monitored by lexA protein and the SOS response. 
D)  involve the formation of chi form intermediates. 
E)  are solely due to nucleic acid structure.

Question 18

If the mismatch repair machinery detects a mismatch soon after DNA replication, it can distinguish the parental strand from the newly synthesized strand by

Accepted Answer

A)  methylation 
B)  the RNA primers 
C)  the Okazaki fragments 
D)  single stranded DNA binding protein 
E)  the degree of supercoiling 
A)  methylation 
B)  the RNA primers 
C)  the Okazaki fragments 
D)  single stranded DNA binding protein 
E)  the degree of supercoiling

Question 19

DNA excision repair

Accepted Answer

A)  involves only two distinct steps. 
B)  requires visible light for activation. 
C)  replaces both strands of a segment of DNA. 
D)  is deficient in some human hereditary diseases. 
E)  is blocked by allopurinol. 
A)  involves only two distinct steps. 
B)  requires visible light for activation. 
C)  replaces both strands of a segment of DNA. 
D)  is deficient in some human hereditary diseases. 
E)  is blocked by allopurinol.

Question 20

Chemicals that bind to DNA by intercalating between the bases

Accepted Answer

A)  can cause frame shift mutations 
B)  can cause deletion mutations 
C)  can cause insertion mutations 
D)  are generally planar hydrophobic molecules 
E)  all of the above 
A)  can cause frame shift mutations 
B)  can cause deletion mutations 
C)  can cause insertion mutations 
D)  are generally planar hydrophobic molecules 
E)  all of the above

Exam 4: DNA Replication, Recombination, and Repair

Replication of DNA must be discontinuous on at least one strand because

Eukaryotic chromatin replication:

An enzyme which can seal a nick in a DNA duplex is called a

Synthesis of the leading strand at the replication fork is carried out by

Why is DNA synthesis started with ribonucleotides rather than deoxyribonucleotides?

DNA synthesis requires a primer. A primer is

Which of the following are not required for the enzymatic synthesis of DNA by DNA polymerase I?

Actinomycin D inhibits the growth of bacteria by

On the lagging strand, the primer on an Okazaki fragment is removed by the '--->exonuclease activity of DNA polymerase I. What enzyme replaces the degraded primer with deoxyribonucleotides?

Frameshift mutations are possible because of

Concerning the polarity of chain elongation during DNA replication

A mutation in which an A-T base pair in DNA is replaced by a G-C base pair is referred to as a(an) mutation.

DNA polymerase I catalyzes the reaction of a

Which of the following enzymes is involved in extending the ends of linear chromosomal DNA?

Which enzyme activity does DNA Pol I not have?

Gyrase (topoisomerase II)

High fidelity DNA replication and repair

If the mismatch repair machinery detects a mismatch soon after DNA replication, it can distinguish the parental strand from the newly synthesized strand by

DNA excision repair

Chemicals that bind to DNA by intercalating between the bases

Eukaryotic Cell Structure

DNA and RNA: Composition and Structure

Protein I: Composition and Structure

RNA: Transcription and Rna Processing

Protein Synthesis: Translation and Posttranslational Modifications

Recombinant Dna and Biotechnology

Regulation of Gene Expression

Protein II: Structure-Function Relationships in Protein Families

Enzymes: Classification, Kinetics, and Control

The Cytochromes P450 and Nitric Oxide Synthases

Biological Membranes: Structure and Membrane Transport

Fundamentals of Signal Transduction

Bioenergetics and Oxidative Metabolism

Carbohydrate Metabolism I: Major Metabolic Pathways and Their Control

Carbohydrate Metabolism II: Special Pathways and Glycoconjugates

Lipid Metabolism I: Synthesis, Storage, and Utilization of Fatty Acids and Triacylglycerols

Lipid Metabolism II: Pathways of Metabolism of Special Lipids

Amino Acid Metabolism

Purine and Pyrimidine Nucleotide Metabolism

Metabolic Interrelationships

Biochemistry of Hormones

Molecular Cell Biology

Cell Cycle, Programmed Cell Death, and Cancer

Digestion and Absorption of Basic Nutritional Constituents

Digestion and Absorption of Basic Nutritional Constituents

Principles of Nutrition I and II

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