BSC 2010 TEST QUESTIONS AND
ANSWERS
Which of the following types of mutation, resulting in an error in the mRNA just after the
AUG start of translation, is likely to have the most serious effect on the polypeptide
product?
a) a deletion of a codon
b) a substitution of the third nucleotide in an ACC codon
c) a deletion of 2 nucleotides
d) a substitution of the first nucleotide of a GGG codon
e) an insertion of a codon - Answer- c) a deletion of 2 nucleotides
What is the effect of a nonsense mutation in a gene?
a) It changes an amino acid in the encoded protein.
b) It alters the reading frame of the mRNA.
c) It introduces a premature stop codon into the mRNA.
d) It has no effect on the amino acid sequence of the encoded protein.
e) It prevents introns from being excised. - Answer- c) It introduces a premature stop
codon into the mRNA.
A frameshift mutation could result from
a) a base deletion only.
b) either an insertion or a deletion of a base.
c) a base insertion only.
d) deletion of three consecutive bases.
e) a base substitution only. - Answer- b) either an insertion or a deletion of a base.
Which of the following DNA mutations is the most likely to be damaging to the protein it
specifies?
a) a point mutation
b) a codon deletion
c) a codon substitution
d) a base-pair deletion
e) a substitution in the last base of a codon - Answer- d) a base-pair deletion
Of the following, which is the most current description of a gene?
a) a DNA - RNA sequence combination that results in an enzymatic product
b) a discrete unit of hereditary information that consists of a sequence of amino acids
c) a unit of heredity that causes formation of a phenotypic characteristic
, d) a DNA sequence that is expressed to form a functional product: either RNA or
polypeptide
e) a DNA subunit that codes for a single complete protein - Answer- d) a DNA sequence
that is expressed to form a functional product: either RNA or polypeptide
In eukaryotic cells, transcription cannot begin until
a) several transcription factors have bound to the promoter.
b) the two DNA strands have completely separated and exposed the promoter.
c) the 5' caps are removed from the mRNA.
d) the DNA introns are removed from the template.
e) DNA nucleases have isolated the transcription unit. - Answer- a) several transcription
factors have bound to the promoter.
Muscle cells differ from nerve cells mainly because they
a) have unique ribosomes.
b) have different chromosomes.
c) use different genetic codes.
d) contain different genes.
e) express different genes. - Answer- e) express different genes.
Some forms of chromatin modification can be passed on to future generations of cells.
a) true
b) false - Answer- a) true
Acetylation of histone tails in chromatin allows access to DNA for transcription.
a) true
b) false - Answer- a) true
Deacetylation of histone tails in chromatin loosens the association between
nucleosomes and DNA.
a) true
b) false - Answer- b) false
Methylation of histone tails in chromatin can promote condensation of the chromatin.
a) true
b) false - Answer- a) true
Acetylation of histone tails is a reversible process
a) true
b) false - Answer- a) true
DNA is not transcribed when chromatin is packaged tightly in a condensed form
a) true
b) false - Answer- a) true
_____ bind(s) to DNA enhancer regions.
ANSWERS
Which of the following types of mutation, resulting in an error in the mRNA just after the
AUG start of translation, is likely to have the most serious effect on the polypeptide
product?
a) a deletion of a codon
b) a substitution of the third nucleotide in an ACC codon
c) a deletion of 2 nucleotides
d) a substitution of the first nucleotide of a GGG codon
e) an insertion of a codon - Answer- c) a deletion of 2 nucleotides
What is the effect of a nonsense mutation in a gene?
a) It changes an amino acid in the encoded protein.
b) It alters the reading frame of the mRNA.
c) It introduces a premature stop codon into the mRNA.
d) It has no effect on the amino acid sequence of the encoded protein.
e) It prevents introns from being excised. - Answer- c) It introduces a premature stop
codon into the mRNA.
A frameshift mutation could result from
a) a base deletion only.
b) either an insertion or a deletion of a base.
c) a base insertion only.
d) deletion of three consecutive bases.
e) a base substitution only. - Answer- b) either an insertion or a deletion of a base.
Which of the following DNA mutations is the most likely to be damaging to the protein it
specifies?
a) a point mutation
b) a codon deletion
c) a codon substitution
d) a base-pair deletion
e) a substitution in the last base of a codon - Answer- d) a base-pair deletion
Of the following, which is the most current description of a gene?
a) a DNA - RNA sequence combination that results in an enzymatic product
b) a discrete unit of hereditary information that consists of a sequence of amino acids
c) a unit of heredity that causes formation of a phenotypic characteristic
, d) a DNA sequence that is expressed to form a functional product: either RNA or
polypeptide
e) a DNA subunit that codes for a single complete protein - Answer- d) a DNA sequence
that is expressed to form a functional product: either RNA or polypeptide
In eukaryotic cells, transcription cannot begin until
a) several transcription factors have bound to the promoter.
b) the two DNA strands have completely separated and exposed the promoter.
c) the 5' caps are removed from the mRNA.
d) the DNA introns are removed from the template.
e) DNA nucleases have isolated the transcription unit. - Answer- a) several transcription
factors have bound to the promoter.
Muscle cells differ from nerve cells mainly because they
a) have unique ribosomes.
b) have different chromosomes.
c) use different genetic codes.
d) contain different genes.
e) express different genes. - Answer- e) express different genes.
Some forms of chromatin modification can be passed on to future generations of cells.
a) true
b) false - Answer- a) true
Acetylation of histone tails in chromatin allows access to DNA for transcription.
a) true
b) false - Answer- a) true
Deacetylation of histone tails in chromatin loosens the association between
nucleosomes and DNA.
a) true
b) false - Answer- b) false
Methylation of histone tails in chromatin can promote condensation of the chromatin.
a) true
b) false - Answer- a) true
Acetylation of histone tails is a reversible process
a) true
b) false - Answer- a) true
DNA is not transcribed when chromatin is packaged tightly in a condensed form
a) true
b) false - Answer- a) true
_____ bind(s) to DNA enhancer regions.
