MMSC 491 EXAM 1 QUESTIONS WITH VERIFIED
ANSWERS
In a DNA double helix each type of base forms a stable base pair with only one type of
base. When bases on an RNA strand are involved in base pairing, which bases can
form stable base pairs with more than one type of base?
Adenine and uracil
Cytosine and uracil
Guanine and uracil
Uracil - Answers - guanine and uracil
Regarding the structure of bases in nucleic acids, which, if any, of the following
statements is incorrect?
Pyrimidines have a single heterocyclic ring consisting of four carbon atoms plus two
nitrogen atoms that are linked to the same carbonyl group
Purines have two heterocyclic rings, each with two nitrogen atoms
Thymine = 5-methyluracil
Pruines carry an amino group, unlike pyrimidines - Answers - purines carry an amino
group, unlike pyrimidines
Regarding the sugar residues in nucleic acids, which, if any, of the following statements
is incorrect?
The sugar is always based on a heterocyclic ring that consists of one oxygen atom and
four carbon atoms, one of which is connected to a fifth carbon atom, the 5 carbon 5'
carbon atom
The internal sugar residues in a DNA strand normally have free hydroxyl groups, unlike
those in an RNA strand.
Bases are covalently linked to the carbon 1' atoms of the sugars.
Neighboring sugar residues are linked to each other by a phosphodiester bond that
connects the 3' carbon atom on one sugar to the 5' carbon atom of its neighbor. -
,Answers - The internal sugar residues in a DNA strand normally have free hydroxyl
groups, unlike those in an RNA strand.
Regarding the DNA replication, which, if any, of the following statements is incorrect?
A) DNA replication is said to be semi-conservative because for each DNA helix only one
strand serves as a template for new DNA synthesis.
B) The two DNA strands of the parental DNA helix are unwound using a DNA helicase.
C) The replication fork marks the point at which DNA is actively being replicated from a
single DNA duplex to form new DNA strands.
D) The synthesis of new DNA strands always proceeds in the 5' → 3' direction. -
Answers - a) DNA replication is said to be semi-conservative because for each DNA
helix only one strand serves as a template for new DNA synthesis.
Regarding DNA replication and DNA synthesis, which, if any, of the following
statements is incorrect?
A) The leading strand is replicated continuously.
B) The lagging strand is replicated discontinuously: the new DNA is synthesized as
short pieces of DNA that must be ligated together.
C) A DNA polymerase always requires a DNA template to synthesize a complementary
DNA.
D) A DNA polymerase requires a short RNA primer when synthesizing new DNA
strands using a DNA template. - Answers - c) A DNA polymerase always requires a
DNA template to synthesize a complementary DNA.
Which is the best definition of noncoding RNA?
A) A mutant mrna that is not capable of making a protein.
B) Any RNA sequence that is not translated to make a protein
C) Any RNA sequence in an mrna, or in the primary transcript used to make the mrna,
that is not translated to make a protein.
D) A functional RNA that is not translated to make a protein. - Answers - d) A functional
RNA that is not translated to make a protein.
If we take the number of chromosomes in a haploid sperm cell or egg cell to be n and
the total content of genomic DNA to be C, what is the number of chromosomes and the
, total genomic DNA content of a diploid G1 phase cell and in a diploid G2 phase cell
from the same organism.
A) n chromosomes, DNA content of 2C in G1; 2n chromosomes, DNA content of 4C in
G2.
B) 2n chromosomes, DNA content of 2C in G1; 4n chromosomes, DNA content of 4C in
G2.
C) 2n chromosomes, DNA content of 2C in G1; 4n chromosomes, DNA content of 2C in
G2.
D) 2n chromosomes, DNA content of 2C in G1; 2n chromosomes, DNA content of 4C in
G2 - Answers - d) 2n chromosomes, DNA content of 2C in G1; 2n chromosomes, DNA
content of 4C in G2
Regarding the cell cycle, which, if any, of the following statements is correct?
A) The M phase and the S phase are the critically important phases of the cell cycle;
according to circumstance, the G2 phase and the G1 phase are dispensable.
B) The M phase is the only phase in the cell cycle when chromosomes stained with
chemical dyes are visible under the light microscope.
C) The G0 phase is a specialized phase that allows terminally differentiated cells to
irretrievably exit the cell cycle and become post-mitotic cells.
D) The G0 phase is a modified version of the G2 phase - Answers - b) The M phase is
the only phase in the cell cycle when chromosomes stained with chemical dyes are
visible under the light microscope.
Which of the following statements is incorrect?
Nucleic acids are always negatively charged
Cellular dnas are structured as a double helix
The only structural difference between DNA and RNA strands is that they have different
sugars, respectively deoxyribose and ribose
Cellular rnas are single-stranded - Answers - the only structural difference between
DNA and RNA strands is that they have different sugars, respectively deoxyribose and
ribose
Which of the following statements is incorrect?
ANSWERS
In a DNA double helix each type of base forms a stable base pair with only one type of
base. When bases on an RNA strand are involved in base pairing, which bases can
form stable base pairs with more than one type of base?
Adenine and uracil
Cytosine and uracil
Guanine and uracil
Uracil - Answers - guanine and uracil
Regarding the structure of bases in nucleic acids, which, if any, of the following
statements is incorrect?
Pyrimidines have a single heterocyclic ring consisting of four carbon atoms plus two
nitrogen atoms that are linked to the same carbonyl group
Purines have two heterocyclic rings, each with two nitrogen atoms
Thymine = 5-methyluracil
Pruines carry an amino group, unlike pyrimidines - Answers - purines carry an amino
group, unlike pyrimidines
Regarding the sugar residues in nucleic acids, which, if any, of the following statements
is incorrect?
The sugar is always based on a heterocyclic ring that consists of one oxygen atom and
four carbon atoms, one of which is connected to a fifth carbon atom, the 5 carbon 5'
carbon atom
The internal sugar residues in a DNA strand normally have free hydroxyl groups, unlike
those in an RNA strand.
Bases are covalently linked to the carbon 1' atoms of the sugars.
Neighboring sugar residues are linked to each other by a phosphodiester bond that
connects the 3' carbon atom on one sugar to the 5' carbon atom of its neighbor. -
,Answers - The internal sugar residues in a DNA strand normally have free hydroxyl
groups, unlike those in an RNA strand.
Regarding the DNA replication, which, if any, of the following statements is incorrect?
A) DNA replication is said to be semi-conservative because for each DNA helix only one
strand serves as a template for new DNA synthesis.
B) The two DNA strands of the parental DNA helix are unwound using a DNA helicase.
C) The replication fork marks the point at which DNA is actively being replicated from a
single DNA duplex to form new DNA strands.
D) The synthesis of new DNA strands always proceeds in the 5' → 3' direction. -
Answers - a) DNA replication is said to be semi-conservative because for each DNA
helix only one strand serves as a template for new DNA synthesis.
Regarding DNA replication and DNA synthesis, which, if any, of the following
statements is incorrect?
A) The leading strand is replicated continuously.
B) The lagging strand is replicated discontinuously: the new DNA is synthesized as
short pieces of DNA that must be ligated together.
C) A DNA polymerase always requires a DNA template to synthesize a complementary
DNA.
D) A DNA polymerase requires a short RNA primer when synthesizing new DNA
strands using a DNA template. - Answers - c) A DNA polymerase always requires a
DNA template to synthesize a complementary DNA.
Which is the best definition of noncoding RNA?
A) A mutant mrna that is not capable of making a protein.
B) Any RNA sequence that is not translated to make a protein
C) Any RNA sequence in an mrna, or in the primary transcript used to make the mrna,
that is not translated to make a protein.
D) A functional RNA that is not translated to make a protein. - Answers - d) A functional
RNA that is not translated to make a protein.
If we take the number of chromosomes in a haploid sperm cell or egg cell to be n and
the total content of genomic DNA to be C, what is the number of chromosomes and the
, total genomic DNA content of a diploid G1 phase cell and in a diploid G2 phase cell
from the same organism.
A) n chromosomes, DNA content of 2C in G1; 2n chromosomes, DNA content of 4C in
G2.
B) 2n chromosomes, DNA content of 2C in G1; 4n chromosomes, DNA content of 4C in
G2.
C) 2n chromosomes, DNA content of 2C in G1; 4n chromosomes, DNA content of 2C in
G2.
D) 2n chromosomes, DNA content of 2C in G1; 2n chromosomes, DNA content of 4C in
G2 - Answers - d) 2n chromosomes, DNA content of 2C in G1; 2n chromosomes, DNA
content of 4C in G2
Regarding the cell cycle, which, if any, of the following statements is correct?
A) The M phase and the S phase are the critically important phases of the cell cycle;
according to circumstance, the G2 phase and the G1 phase are dispensable.
B) The M phase is the only phase in the cell cycle when chromosomes stained with
chemical dyes are visible under the light microscope.
C) The G0 phase is a specialized phase that allows terminally differentiated cells to
irretrievably exit the cell cycle and become post-mitotic cells.
D) The G0 phase is a modified version of the G2 phase - Answers - b) The M phase is
the only phase in the cell cycle when chromosomes stained with chemical dyes are
visible under the light microscope.
Which of the following statements is incorrect?
Nucleic acids are always negatively charged
Cellular dnas are structured as a double helix
The only structural difference between DNA and RNA strands is that they have different
sugars, respectively deoxyribose and ribose
Cellular rnas are single-stranded - Answers - the only structural difference between
DNA and RNA strands is that they have different sugars, respectively deoxyribose and
ribose
Which of the following statements is incorrect?
