BIO 235 - Final Exam Study Guide Questions
and Answers Verified by Experts
When codons that specify the same amino acid differ in ________, a single tRNA may be able to
anneal to several of them through wobble base pairing.
A. Any one of their nucleotides
B. Any two or their nucleotides
C. Their 5' nucleotide
D. Their middle nucleotide
E. Their 3' nucleotide Correct Answ_E (wobble takes place on the THIRD position of a
codon and the FIRST position of the anticodon)
Where does wobble take place on the codon? (5' end or 3' end?) Correct Answ_3' end (third
position)
Where does wobble take place on the anticodon? (5' end or 3' end?) Correct Answ_5' end
(first position)
Through wobble, a single __________ can pair wit more than one __________.
A. codon; anticodon
B. group of three nucleotides in DNA; codon in mRNA
C. tRNA; amino acid
D. Anticodon; codon Correct Answ_D
The increase in number (expansion) of three-nucleotide repeats is responsible for?
A. Sickle-cell anemia
B. Xeroderma pigmentosum
C. Alkaptonuria
,D. Trisomy 21
E. Fragile X syndrome
F. None of the above Correct Answ_E
How many copies of the CGG repeat does a normal/unaffected person? (fragile X syndrome)
Correct Answ_Less than 55 (60)
How many copies of the CGG repeat does a premutated individual have? (fragile X syndrome)
Correct Answ_55-230
How many copies of the CGG repeat does an affected individual have? (fragile X syndrome)
Correct Answ_more than 230
Are somatic mutations inherited? Correct Answ_NO (produce patches - basis for cancers)
Are germ-line mutations inherited? Correct Answ_YES
Intragenic suppressor mutation Correct Answ_Takes place in the same gene as that
containing the mutation being suppressed (may change a second nucleotide in the SAME codon
altered by the original mutation OR suppress a frameshift mutation with an insertion or deletion)
Intergenic suppressor mutation Correct Answ_Occurs in a gene other than the one bearing
the original
What causes xeroderma pigmentosum? Correct Answ_Autosomal recessive condition where
people lack nucleotide-excision repair enzymes
The Ames test relies on the rate of a mutation in a bacterium. What is the direction of this
mutation?
A. Auxotrophic bacterial cells turn into prototrophs
, B. Prototrophic bacterial cells turn into auxotrophs
C. Heterotrophic organisms turn into phototrophic organism
D. A wild-type bacterium turns into a mutant bacterium
E. A heterozygous organism turns into homozygous one Correct Answ_A (his- to his+)
A silent mutation is a nucleotide change in the DNA sequence which
A. Does not result in an amino change
B. Converts a sense codon to a non-sense codon
C. Causes a missense mutation, but the altered amino acid has similar characteristics as the wild-
type amino acid, and the altered polypeptide remains functional
D. Causes a missense mutation, and the altered amino acid differs from the wild-type amino acid,
and the altered polypeptide is dysfunctional
E. Results in a frameshift Correct Answ_A
Insertion Correct Answ_Addition of a nucleotide pair
Deletion Correct Answ_Deletion of a nucleotide pair
Frameshift mutations Correct Answ_Changes in the reading frame of a gene (results from an
insertion or a deletion)
Missense mutation Correct Answ_Base substitution that results in a different amino acid in
the protein
Nonsense mutation Correct Answ_Changes a sense codon (one that specifies an amino acid)
to a nonsense codon (stop codon that terminates translation)
Silent mutations Correct Answ_Changes a codon to a synonymous codon that specifies the
same amino acid (alters the DNA sequence without changing the amino acid sequence)
and Answers Verified by Experts
When codons that specify the same amino acid differ in ________, a single tRNA may be able to
anneal to several of them through wobble base pairing.
A. Any one of their nucleotides
B. Any two or their nucleotides
C. Their 5' nucleotide
D. Their middle nucleotide
E. Their 3' nucleotide Correct Answ_E (wobble takes place on the THIRD position of a
codon and the FIRST position of the anticodon)
Where does wobble take place on the codon? (5' end or 3' end?) Correct Answ_3' end (third
position)
Where does wobble take place on the anticodon? (5' end or 3' end?) Correct Answ_5' end
(first position)
Through wobble, a single __________ can pair wit more than one __________.
A. codon; anticodon
B. group of three nucleotides in DNA; codon in mRNA
C. tRNA; amino acid
D. Anticodon; codon Correct Answ_D
The increase in number (expansion) of three-nucleotide repeats is responsible for?
A. Sickle-cell anemia
B. Xeroderma pigmentosum
C. Alkaptonuria
,D. Trisomy 21
E. Fragile X syndrome
F. None of the above Correct Answ_E
How many copies of the CGG repeat does a normal/unaffected person? (fragile X syndrome)
Correct Answ_Less than 55 (60)
How many copies of the CGG repeat does a premutated individual have? (fragile X syndrome)
Correct Answ_55-230
How many copies of the CGG repeat does an affected individual have? (fragile X syndrome)
Correct Answ_more than 230
Are somatic mutations inherited? Correct Answ_NO (produce patches - basis for cancers)
Are germ-line mutations inherited? Correct Answ_YES
Intragenic suppressor mutation Correct Answ_Takes place in the same gene as that
containing the mutation being suppressed (may change a second nucleotide in the SAME codon
altered by the original mutation OR suppress a frameshift mutation with an insertion or deletion)
Intergenic suppressor mutation Correct Answ_Occurs in a gene other than the one bearing
the original
What causes xeroderma pigmentosum? Correct Answ_Autosomal recessive condition where
people lack nucleotide-excision repair enzymes
The Ames test relies on the rate of a mutation in a bacterium. What is the direction of this
mutation?
A. Auxotrophic bacterial cells turn into prototrophs
, B. Prototrophic bacterial cells turn into auxotrophs
C. Heterotrophic organisms turn into phototrophic organism
D. A wild-type bacterium turns into a mutant bacterium
E. A heterozygous organism turns into homozygous one Correct Answ_A (his- to his+)
A silent mutation is a nucleotide change in the DNA sequence which
A. Does not result in an amino change
B. Converts a sense codon to a non-sense codon
C. Causes a missense mutation, but the altered amino acid has similar characteristics as the wild-
type amino acid, and the altered polypeptide remains functional
D. Causes a missense mutation, and the altered amino acid differs from the wild-type amino acid,
and the altered polypeptide is dysfunctional
E. Results in a frameshift Correct Answ_A
Insertion Correct Answ_Addition of a nucleotide pair
Deletion Correct Answ_Deletion of a nucleotide pair
Frameshift mutations Correct Answ_Changes in the reading frame of a gene (results from an
insertion or a deletion)
Missense mutation Correct Answ_Base substitution that results in a different amino acid in
the protein
Nonsense mutation Correct Answ_Changes a sense codon (one that specifies an amino acid)
to a nonsense codon (stop codon that terminates translation)
Silent mutations Correct Answ_Changes a codon to a synonymous codon that specifies the
same amino acid (alters the DNA sequence without changing the amino acid sequence)
