Chapter 3: The Chemical Building Blocks of Life
The correct structure of DNA components can be presented as
A) phosphate–base–sugar.
B)
C)
D)
E)
phosphate–sugar–base.
base–phosphate–sugar.
phosphate–sugar–phosphate–base.
base–sugar–phosphate–base.
Which of the following is a characteristic of double-stranded DNA?
A) 2 nanometers in width
B)
C)
D)
E)
10 base pairs per turn
0.34 nanometers per basepair
A and B
A, B and C
Which of the following DNA molecules is the most stable?
A) CTGCATAC
GACGTATG
B) GAAATTTC
CTTTAAAG
C) AGTCGAAT
TCAGCTTA
D) GCGTGCAC
CGCACGTG
E) GGATCCTG
CCTAGGAC
Doubled-stranded DNA consists of two antiparallel strands, meaning that one strand is oriented in the 5’ to 3’
direction, while the other is oriented in the 3’ to 5’ direction.
A) True
B) False
Asymmetrical spacing of the backbones of the DNA double helix generates major and minor grooves.
A) True
B) False
Simple Gene Expression
Which of the following best describes transcription?
A) DNA -> DNA
B) DNA -> RNA
C) DNA -> Protein
D) RNA -> DNA
E) RNA -> Protein
Which of the following best describes translation?
A) DNA -> DNA
B) DNA -> RNA
C) DNA -> Protein
D) RNA -> DNA
E) RNA -> Protein
Nucleotides are the building blocks of
A) DNA only.
B) RNA only.
C) both DNA and RNA.
D) neither DNA nor RNA.
E) cells.
A structural gene encodes the information for a specific protein.
A) True
B) False
The amino acid sequence of a protein determines its shape and specific function.
A) True
B) False
DNA replication is said to be
A) dispersive.
B) semi-conservative.
C) conservative.
D) liberal.
E) inconclusive.
Which of the following DNA sequences is complementary to 5’ TAGAC 3’?
A) 5’ TAGAC 3’
B) 5’ ATCTG 3’
C) 5’ GTCTA 3’
D) 5’ CAGAT 3’
E) none of the above
According to Chargaff’s rule,
which of the following statements
about double-stranded DNA is
TRUE?
A) A = T
and C
=G
B) A + G
=C+
T
C) A + T
=C+
G
D) A and
B
E) A, B,
and C
The newly-synthesized strand of DNA has
exactly the same base sequence as that of its
template strand.
A) True
B) False
The DNA replication machinery is assembled at the replication
fork.
A) True
B) False
1
The genetic material in bacteria is
Correct
A) double-stranded DNA.
B) double-stranded RNA.
C) single-stranded DNA.
D) single-stranded RNA.
E) either A or B
2
DNA replication in bacteria begins at
Correct
A) a single origin and proceeds in one direction.
B) a single origin and proceeds in both directions.
C) two origins and proceeds in both directions.
D) many origins and proceeds in one direction.
E) many origins and proceeds in one direction.
3
DNA replication is said to be
Correct
A) dispersive.
B) semi-conservative.
C) conservative.
D) liberal.
E) none the above
4
DNA replication does not require a template.
Correct
A) True
B) False
5
The bacterial chromosome is linear.
Correct
A) True
B) False
1
Arrange the following proteins in the proper order in which they
participate in DNA replication.
Correct
1 = Primase
2 = Helicase
3 = Single-strand binding proteins
4 = DNA polymerase I
A) 1, 2, 3, 4
B) 1, 3, 2, 4
C) 2, 3, 1, 4
D) 2, 3, 4, 1
E) 2, 4, 3, 1
2
Which of the following is required to replicate the lagging strand of
DNA?
Correct
A) Okazaki fragments
B) primase
C) DNA ligase
D) A and B
E) A, B and C
3
RNA primers are removed by the action of the enzyme
Incorrect
A) DNA pol III.
B) DNA pol I.
C) primase.
D) helicase.
E) phophodiesterase.
4
DNA pol III can initiate DNA synthesis.
Incorrect
A) True
B) False
5
To allow simultaneous replication of the leading and lagging strands by
dimeric DNA pol III, the DNA of the leading strand has to be folded.
Correct
A) True
B) False
1
Which of the following prevents supercoiling of the DNA strands ahead
of the replication bubble?
Correct
A) helicase
B) topoisomerase
C) DNA binding proteins
D) DnaA
E) all of the above
2
Which of the following molecules initiates the formation of the
replication bubble?
Incorrect
A) helicase
B) DNA polymerase
C) DnaA
D) topoisomerase
E) DNA primase
3
Which of the following synthesizes the daughter strands during DNA
replication?
Correct
A) DNA primase
B) helicase
C) RNA polymerase
D) DNA polymerase
E) topoisomerase
4
Synthesis of the daughter DNA strand from the leading strand template
occurs in a 5’ to 3’ direction.
Correct
A) True
B) False
5
Okazaki fragments are involved in the replication of the leading strand
in a replication bubble.
Correct
A) True
B) False
1
The enzyme that unwinds a segment of the DNA molecule is...
Incorrect
A) DNA polymerase.
B) DNA ligase.
C) RNA primase.
D) DNA polymerase III.
E) helicase.
2
The enzyme that travels along the leading strand assembling new
nucleotides on a growing new strand of DNA is...
Incorrect
A) DNA polymerase.
B) DNA ligase.
C) RNA primase.
D) DNA polymerase III.
E) helicase.
3
Before the lagging strand can begin assembling new DNA nucleotides,
which of the following must occur?
Incorrect
A) DNA polymerase III adds deoxyribonucleotides.
B) DNA polymerase I removes some material and replaces it with
DNA.
C) OH bonds must be broken between the two strands of DNA.
D) DNA ligase forms a phosphodiester bond between the 3' OH of
the growing strand and the 5' phosphate in front of it.
E) RNA primase constructs a short RNA primer.
4
During DNA replication, the lagging strand is synthesized continuously,
while the leading strand is synthesized discontinuously.
Correct
A) True
B) False
5
Before DNA replication can occur, the OH bonds between the strands
must be broken.
Incorrect
A) True
B) False
1
The enzyme that unwinds a segment of the DNA molecule is...
Incorrect
A) DNA polymerase.
B) DNA ligase.
C) RNA primase.
D) DNA polymerase III.
E) helicase.
2
The enzyme that travels along the leading strand assembling new
nucleotides on a growing new strand of DNA is...
Incorrect
A) DNA polymerase.
B) DNA ligase.
C) RNA primase.
D) DNA polymerase III.
E) helicase.
3
Before the lagging strand can begin assembling new DNA nucleotides,
which of the following must occur?
Incorrect
A) DNA polymerase III adds deoxyribonucleotides.
B) DNA polymerase I removes some material and replaces it with
DNA.
C) OH bonds must be broken between the two strands of DNA.
D) DNA ligase forms a phosphodiester bond between the 3' OH of
the growing strand and the 5' phosphate in front of it.
E) RNA primase constructs a short RNA primer.
4
Incorrect
During DNA replication, the lagging strand is synthesized continuously,
while the leading strand is synthesized discontinuously.
A) True
B) False
5
Before DNA replication can occur, the OH bonds between the strands
must be broken.
Incorrect
A) True
B) False
1
Which of the following are limitations of DNA polymerase?
Incorrect
A) it can only add bases to the exposed 5' end of a pre-existing
strand
B) it can only replicate the leading strand
C) it can only replicate the lagging strand
D) all of the above
E) none of the above
2
The enzyme ________ unzips and unwinds the DNA molecule.
Incorrect
A) DNA polymerase
B) helicase
C) primase
D) DNA ligase
E) unzipase
3
Incorrect
Which of the following statements about DNA replication is TRUE?
A) the leading strand is replicated continuously, while the lagging
strand is replicated discontinuously
B) the leading strand is replicated discontinuously, while the
lagging strand is replicated continuously
C) both the leading and lagging strands are replicated
continuously
D) both the leading and lagging strands are replicated
discontinuously
E) each of the leading and lagging strands is replicated both
continuously and discontinuously
4
Incorrect
DNA replication results in two identical daughter molecules each
consisting of one old (original) strand and one newly-synthesized
strand.
A) True
B) False
5
The point where separation of the DNA occurs is called the replication
fork.
Correct
A) True
B) False
1
UV light and other ionizing radiations damage DNA molecules by...
Correct
A) creating guanine dimmers between adjacent guanines in the
DNA chain.
B) creating adenine dimmers between adjacent adenines in the
DNA chain.
C) creating thymine dimmers between adjacent thymines in the
DNA chain.
D) creating uracil dimmers between adjacent uracils in the DNA
chain.
E) creating cytosine dimmers between adjacent cytosines in the
DNA chain.
2
These dimmers weaken...
Incorrect
A) hydrogen bonds.
B) sulfide bonds.
C) covalent bonds.
D) ionic bonds.
E) all of these.
3
These dimmers are repaired by...
Incorrect
A) the enzyme DNA photolyase.
B) exposure to light.
C) transfer of an electron to the dimer.
D) A and B.
E) A, B and C.
4
Chemical agents can cause mutations by inducing ethylation of
guanine residues in DNA.
Correct
A) True
B) False
5
The enzyme ethylguanine-DNA ethyltransferase prevents DNA
mutations from occurring.
Correct
A) True
B) False
1
What protein cuts the damaged DNA strand?
Incorrect
A) UvrB
B) UvrC
C) UvrD
D) UvrA
2
Which protein has a helicase function?
Correct
A) UvrB
B) UvrC
C) UvrD
D) UvrA
3
Which of the following synthesizes the new DNA strand?
Incorrect
A) DNA ligase
B) DNA polymerase
C) DNA helicase
D) UvrA-UvrB trimer
4
Nucleotide excision repair only repairs pyrimidine dimmers.
Incorrect
A) True
B) False
5
In nucleotide excision repair, both strands of the DNA are cut and
repaired using DNA polymerase and DNA ligase.
Incorrect
A) True
B) False
1
Incorrect
Arrange the following proteins in the proper sequence in which they
participate in methyl-directed mismatch repair.
1. Mut S
2. Mut L
3. Mut H
A) 1, 2, 3
B) 2, 1, 3
C) 2, 3, 1
D) 3, 2, 1
E) 3, 1, 2
2
In methyl-directed mismatch repair, the strand that is repaired is
Incorrect
A) the methylated strand.
B) the non-methylated strand.
C) the hemi-methylated strand.
D) either the methylated or non-methylated, depending on the
type of mismatch.
E) either the methylated or non-methylated, depending on the
size of mismatch.
3
Methylation of DNA typically occurs at sites with the sequence
Incorrect
A) ATAT.
B) CTGA.
C) AGGA.
D) GTTG.
E) GATC.
4
DNA pol III and DNA ligase are required to fill in the repair gap.
Incorrect
A) True
B) False
5
The MutH protein is directly responsible for recognizing mismatched
DNA base pairs.
Incorrect
A) True
B) False
1
Correct
The proofreading function of DNA polymerase reduces the error rate
from about one in a million basepairs to about one in a ________
basepairs.
A) hundred thousand
B) ten thousand
C) thousand
D) ten million
E) hundred million
2
DNA polymerases use their ________ activity to remove a mismatched
basepair.
Incorrect
A) 3’ -> 5’ exonuclease
B) 5’ -> 3’ exonuclease
C) RNase
D) protease
E) mismatchase
3
Proofreading by DNA polymerase involves the removal of
Incorrect
A) only the mismatched base on the old strand of DNA.
B) only the mismatched base on the newly-synthesized strand
of DNA.
C) the mismatched basepair on both strands of DNA.
D) several bases on the newly-synthesized strand of DNA.
E) several bases on the old strand of DNA.
4
Improper base-pairing during DNA replication causes a pause in chain
elongation.
Incorrect
A) True
B) False
5
Following base removal, DNA polymerase can add nucleotides in the
5’ to 3’ direction.
Incorrect
A) True
B) False