Question 1

In the Watson-Crick DNA model, how many base pairs are found in one turn of the helix?

Accepted Answer

A)  4
B)  6
C)  8
D)  10
E)  12F) B) and C)
G) A) and D)

Question 2

Which of the following is correctly paired?

Accepted Answer

A)  adenine: pyrimidine
B)  RNA: ribose containing nucleic acid
C)  thymine: purine
D)  uracil: purine
E)  DNA: ribose containing nucleic acidF) A) and E)
G) A) and B)

Question 3

Based on the following, what can be said about the synthesis of polynucleotides?

Accepted Answer

A)  polynucleotides are unstable and are rapidly degraded
B)  polynucleotide formation is made much more exergonic by the hydrolysis of pyrophosphate
C)  the hydrolysis of nucleoside triphosphates is the only driving force to make an overall irreversible reaction
D)  polynucleotides are highly resistant to hydrolysis, even in the presence of an acid catalyst
E)  none of the aboveF) None of the above
G) A) and C)

Question 4

Which of the following bases is found only in DNA?

Accepted Answer

A)  adenine
B)  thymine
C)  uracil
D)  cytosine
E)  guanineF) A) and C)
G) B) and D)

Question 5

Replication of DNA is best considered __________.

Accepted Answer

A)  conservative
B)  semiconservative
C)  dispersive
D)  complementary
E)  none of the aboveF) B) and C)
G) B) and D)

Question 6

Which of the following describes the directionality seen in nucleic acids?

Accepted Answer

A)  most polynucleotides have an unreacted 5' hydroxyl group
B)  all polynucleotides have an unreacted 2' hydroxyl group
C)  most polynucleotides have a phosphate group on the 5'end
D)  sequences of polynucleotides are generally written from 3' on the left to 5' on the right
E)  none of the aboveF) None of the above
G) B) and E)

Question 7

Which of the following types of DNA are often supercoiled?

Accepted Answer

A)  extremely long linear DNA, such as seen in human chromosomes
B)  very short linear DNA
C)  circular DNA
D)  DNA molecules that contain both circular and linear regions
E)  all of the aboveF) A) and D)
G) C) and D)

Question 8

Base stacking, or the "stacking interaction," is most likely the result of which noncovalent interaction

Accepted Answer

A)  charge-dipole interaction
B)  dipole-dipole interaction
C)  dipole-induced dipole interaction
D)  van der Waals interaction
E)  none of the aboveF) A) and B)
G) C) and D)

Question 9

While RNA is often single stranded, transfer RNA (tRNA) is usually found with some double stranded structure. Which of the following explains this?

Accepted Answer

A)  tRNAs contain self-complimentary stem-loop structures
B)  after synthesis, tRNA molecules are hydrolyzed in specific places to allow double stranded structures to form
C)  regions of tRNAs become supercoiled, thus forcing formation of double stranded regions
D)  tRNAs adopt a form much like Z-DNA allowing double stranded regions to form
E)  none of the aboveF) B) and D)
G) A) and C)

Question 10

Which of the following, when paired with its complementary strand, would have the highest Tm?

Accepted Answer

A)  AAGTTCCAGT
B)  GCAGCAGCAT
C)  ATTACGAGCT
D)  GCGAAATCAA
E)  TGACCTTGAAF) A) and E)
G) A) and B)

Question 11

Where are G-quadruplexes most commonly found?

Accepted Answer

A)  transcription termination sites
B)  origin of replication
C)  the ends of hairpin loops
D)  telomeres
E)  none of the aboveF) A) and B)
G) B) and D)

Question 12

Based on the following, which is true regarding the acid/base properties of guanine?

Accepted Answer

A)  at physiological pH, guanine will be positively charged
B)  at physiological pH, guanine will be negatively charged
C)  at physiological pH, guanine will be neutral
D)  at physiological pH, guanine will be a very effective buffer against base
E)  at physiological pH, guanine will be a very effective buffer against acidF) B) and C)
G) C) and D)

Question 13

The following shows deoxyadenosine in the _____ conformation

Accepted Answer

A)  syn
B)  anti
C)  cis
D)  trans
E)  none of the aboveF) C) and E)
G) B) and E)

Question 14

In a circular DNA molecule of 126 bp with 10.5 bp/turn, which of the following represents an unstrained circle? (L = linking number, T = twist and W = writhe)

Accepted Answer

A)  L = 12, T = 12, W = 0
B)  L = 11, T = 11, W = 0
C)  L = 11, T = 12, W = -1
D)  L = 12, T = 11, W = +1
E)  L = 11, T = 10, W = 0F) None of the above
G) All of the above

Question 15

Which of the following is correct regarding the flow of genetic information?

Accepted Answer

A)  replication uses a DNA template to form RNA which serves as the new template for DNA synthesis
B)  transcription produces RNA from a DNA template using the enzyme RNA polymerase
C)  translation uses mRNA as a template, rRNA to carry amino acids, and tRNA to catalyze the synthesis of proteins
D)  during both replication and transcription, the products are double stranded polynucleotides
E)  none of the aboveF) A) and E)
G) B) and D) B

Question 16

Which of the following is a major difference between B-DNA and A-DNA?

Accepted Answer

A)  B-DNA has a right-handed helix, A-DNA has a left-handed helix
B)  B-DNA has 10 residues per helix turn while A-DNA has 9
C)  B-DNA base pairs are stacked almost parallel to one another while A-DNA base pairs are significantly tilted with respect to each other
D)  the major groove of A-DNA is much larger than that in B-DNA
E)  none of the aboveF) B) and E)
G) A) and B)

Question 17

Draw the structure of cytosine and thymine, then show the most common tautomer of each.

Accepted Answer

The answer of Draw the structure of cytosine and thymine,...

Question 18

Which of the following is correctly paired with the type of tautomerization(s) that occurs?

Accepted Answer

A)  adenine: keto-enol
B)  cytosine: amino-imino and keto-enol
C)  guanine: amino-imino
D)  thymine: keto-enol
E)  none of the aboveF) A) and B)
G) C) and E) D

Question 19

Which of the following techniques was used to determine the double helical structure of DNA?

Accepted Answer

A)  NMR spectroscopy
B)  X-ray diffraction
C)  Raman spectroscopy
D)  UV/Vis spectroscopy
E)  IR spectroscopyF) C) and D)
G) A) and C)

Question 20

Which of the following best explains why the ratios of A/T and G/C are 0.77 and 1.08, respectively in bacteriophage  Φ\varPhiΦ X174?

Accepted Answer

A)  the base pairing in bacteriophages is not always A-T and C-G
B)  studies done with most bacteriophages do not use complete genomic DNA due to the inherent instability of phage DNA
C)  bacteriophage DNA often uses bases other than A, T, C and G
D)  many viruses often use single stranded DNA
E)  none of the above F) A) and B)
G) None of the above D

Exam 4: Nucleic Acids

In the Watson-Crick DNA model, how many base pairs are found in one turn of the helix?

Correct AnswerverifiedShow Answer

Which of the following is correctly paired?

Correct AnswerverifiedShow Answer

Based on the following, what can be said about the synthesis of polynucleotides?

Correct AnswerverifiedShow Answer

Which of the following bases is found only in DNA?

Correct AnswerverifiedShow Answer

Replication of DNA is best considered __________.

Correct AnswerverifiedShow Answer

Which of the following describes the directionality seen in nucleic acids?

Correct AnswerverifiedShow Answer

Which of the following types of DNA are often supercoiled?

Correct AnswerverifiedShow Answer

Base stacking, or the "stacking interaction," is most likely the result of which noncovalent interaction

Correct AnswerverifiedShow Answer

While RNA is often single stranded, transfer RNA (tRNA) is usually found with some double stranded structure. Which of the following explains this?

Correct AnswerverifiedShow Answer

Which of the following, when paired with its complementary strand, would have the highest Tm?

Correct AnswerverifiedShow Answer

Where are G-quadruplexes most commonly found?

Correct AnswerverifiedShow Answer

Based on the following, which is true regarding the acid/base properties of guanine?

Correct AnswerverifiedShow Answer

The following shows deoxyadenosine in the _____ conformation

Correct AnswerverifiedShow Answer

In a circular DNA molecule of 126 bp with 10.5 bp/turn, which of the following represents an unstrained circle? (L = linking number, T = twist and W = writhe)

Correct AnswerverifiedShow Answer

Which of the following is correct regarding the flow of genetic information?

Correct AnswerverifiedB

Which of the following is a major difference between B-DNA and A-DNA?

Correct AnswerverifiedShow Answer

Draw the structure of cytosine and thymine, then show the most common tautomer of each.

Correct AnswerverifiedShow Answer

Which of the following is correctly paired with the type of tautomerization(s) that occurs?

Correct AnswerverifiedD

Which of the following techniques was used to determine the double helical structure of DNA?

Correct AnswerverifiedShow Answer

Which of the following best explains why the ratios of A/T and G/C are 0.77 and 1.08, respectively in bacteriophage Φ\varPhiΦ X174?

Correct AnswerverifiedD

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Which of the following, when paired with its complementary strand, would have the highest T_m?

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B

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D

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Which of the following best explains why the ratios of A/T and G/C are 0.77 and 1.08, respectively in bacteriophage $\varPhi$ X174?

Correct Answer
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D