1
MMSC 491 EXAM 1 /WELL STRUCTURED QUESTIONS
AND CORRECT ANSWERS 2024/2025 GRADED A+.
With reference to aberrant methylation of bases which of the following
statements, if any, is false?
A. S-adenosylmethionine donates methyl groups to a range of different molecules
in cells and frequently inappropriately methylates bases in DNA.
B. Guanine is occasionally methylated to give O-6-methylguanine which base pairs
with adenine rather than with cytidine.
C. In each nucleated cell, about 300-600 adenines are converted to 3-
methyladenine per day.
D. 3-methyladenine can be a cytotoxic base: it distorts the double helix and that
can disrupt crucial DNA-protein interactions. - (answers)B
With reference to base cross-linking, which, if any, of the following statements, is
false?
A. Base cross-linking means that covalent bonds form between two bases.
B. The cross-linked bases are on opposing DNA strands.
C. The anti-cancer agent cisplatin causes a type of cross-linking between two
guanine residues.
D. Pyrimidine dimers are a type of base cross-linking that is commonly induced by
excess exposure to sunlight. - (answers)B
Which, if any, of the following statements is false, regarding the sources of
genetic variation?
, 2
A. Most of the inherited changes in our DNA arise because of exposure to
extracellular mutagens, including radiation sources and chemical mutagens.
B. Most of the inherited changes in our DNA arise because of unavoidable
endogenous errors in cellular mechanisms and harmful effects of certain natural
molecules and atoms within our cells.
C. Errors in DNA replication and DNA repair are a major source of mutations in our
cells.
D. Significant chemical damage is sustained by DNA because of its proximity to
water molecules in our cells. - (answers)A
Nucleic acid hybridization assays are normally carried out under relaxed
hybridization stringency (to maximize the chances of heteroduplex formation) but
afterwards, washes are carried out that can be designed to favor perfectly
matched sequences only by changing some parameter. Which, if any, of the
following changes would be consistent with that aim?
a) An increase in temperature.
b) An increase in salt concentration.
c) An increase in the concentration of a polar molecule, such as urea or
formamide.
d) Both A and C
, 3
E) A, B, and C - (answers)D
Which of the following statements, if any, is false?
A. PCR requires the use of a heat-stable DNA polymerase to make copies of the
template DNA.
B. PCR is usually used to amplify a specific DNA sequence of interest using
C. Oligonucleotide primers that bind to closely flanking sequences.
D. PCR is superior to cell-based DNA cloning for two major reasons: it is much
quicker and it allows much greater DNA amplification. - (answers)D
For many of our genes, the initial RNA transcript needs to be cleaved into pieces.
Some of the pieces, called ____ ____, are discarded, but other alternating pieces
called ___ ____ are retained and fused in the same linear order as their order
when transcribed. - (answers)introns, exons
Which, if any, of the following statements are false?
a) Constitutive heterochromatin remains highly condensed throughout the cell
cycle.
b) Unlike constitutive heterochromatin, facultative heterochromatin describes
chromatin that
can de-condense and behave as euchromatin under certain circumstances.
MMSC 491 EXAM 1 /WELL STRUCTURED QUESTIONS
AND CORRECT ANSWERS 2024/2025 GRADED A+.
With reference to aberrant methylation of bases which of the following
statements, if any, is false?
A. S-adenosylmethionine donates methyl groups to a range of different molecules
in cells and frequently inappropriately methylates bases in DNA.
B. Guanine is occasionally methylated to give O-6-methylguanine which base pairs
with adenine rather than with cytidine.
C. In each nucleated cell, about 300-600 adenines are converted to 3-
methyladenine per day.
D. 3-methyladenine can be a cytotoxic base: it distorts the double helix and that
can disrupt crucial DNA-protein interactions. - (answers)B
With reference to base cross-linking, which, if any, of the following statements, is
false?
A. Base cross-linking means that covalent bonds form between two bases.
B. The cross-linked bases are on opposing DNA strands.
C. The anti-cancer agent cisplatin causes a type of cross-linking between two
guanine residues.
D. Pyrimidine dimers are a type of base cross-linking that is commonly induced by
excess exposure to sunlight. - (answers)B
Which, if any, of the following statements is false, regarding the sources of
genetic variation?
, 2
A. Most of the inherited changes in our DNA arise because of exposure to
extracellular mutagens, including radiation sources and chemical mutagens.
B. Most of the inherited changes in our DNA arise because of unavoidable
endogenous errors in cellular mechanisms and harmful effects of certain natural
molecules and atoms within our cells.
C. Errors in DNA replication and DNA repair are a major source of mutations in our
cells.
D. Significant chemical damage is sustained by DNA because of its proximity to
water molecules in our cells. - (answers)A
Nucleic acid hybridization assays are normally carried out under relaxed
hybridization stringency (to maximize the chances of heteroduplex formation) but
afterwards, washes are carried out that can be designed to favor perfectly
matched sequences only by changing some parameter. Which, if any, of the
following changes would be consistent with that aim?
a) An increase in temperature.
b) An increase in salt concentration.
c) An increase in the concentration of a polar molecule, such as urea or
formamide.
d) Both A and C
, 3
E) A, B, and C - (answers)D
Which of the following statements, if any, is false?
A. PCR requires the use of a heat-stable DNA polymerase to make copies of the
template DNA.
B. PCR is usually used to amplify a specific DNA sequence of interest using
C. Oligonucleotide primers that bind to closely flanking sequences.
D. PCR is superior to cell-based DNA cloning for two major reasons: it is much
quicker and it allows much greater DNA amplification. - (answers)D
For many of our genes, the initial RNA transcript needs to be cleaved into pieces.
Some of the pieces, called ____ ____, are discarded, but other alternating pieces
called ___ ____ are retained and fused in the same linear order as their order
when transcribed. - (answers)introns, exons
Which, if any, of the following statements are false?
a) Constitutive heterochromatin remains highly condensed throughout the cell
cycle.
b) Unlike constitutive heterochromatin, facultative heterochromatin describes
chromatin that
can de-condense and behave as euchromatin under certain circumstances.
