Deck 9: Gene Mutations

Question 1

Which of the following laboratory methods used to detect mutations relies on differences in dissociation of double-stranded DNA into single-stranded DNA at different points in a gel?

A) Denaturing gradient gel electrophoresis
B) HPLC
C) Allele-specific oligomer hybridization
D) Inversion probe assay

Answer 1

Denaturing gradient gel electrophoresis

Question 2

A patient with a family history of breast cancer, in which several affected relatives have a known mutation in the BRCA1 gene, is screened for the presence of the mutation by allele-specific oligomer hybridization. Signal from the labeled oligomer corresponding to the normal sequence was observed when exposed to the patient's sample. Signal was also observed when the labeled oligomer of the mutant sequence was tested with the patient's sample. Which of the following corresponds to the correct interpretation of these results?

A) The patient has a normal BRCA1 sequence.
B) The patient has a heterozygous mutation in BRCA1.
C) The patient has a homozygous mutation in BRCA1.
D) The results are not valid.

Answer 2

The patient has a heterozygous mutation in BRCA1.

Question 3

Substitution of leucine with valine in an amino acid sequence is what type of mutation?

A) Conservative
B) Non-conservative
C) Silent
D) Nonsense

Answer 3

Conservative

Question 4

Mass spectrometry detects what type or particles?

A) Uncharged
B) Ions
C) Very large proteins
D) Hydrophobic

Question 5

A single-strand conformation polymorphism (SSCP) procedure has been performed on a patient sample, and the results were compared with those from a normal reference sample. The patient bands resolved in different locations on the gel as compared with the reference bands. These results would be interpreted as which of the following?

A) The patient sample is normal.
B) The patient has a mutation in the targeted region.
C) The results are invalid.
D) The patient sample is a mixture of normal and mutated sequences.

Question 6

What does the g designate in g.225A>C?

A) Gene sequence
B) Gradient
C) Genomic sequence
D) Genetic

Question 7

Which of the following assays can be used in high-throughput applications?

A) Melt curve assay
B) Heteroduplex analysis
C) PCR-RFLP
D) Homogenous MassExtend

Question 8

Which of the following methodologies was used in the Human Haplotype Mapping Project?

A) Melt curve analysis
B) Denaturing gradient gel electrophoresis
C) Protein truncation test
D) Inversion probe assay

Question 9

A melt curve analysis was performed to genotype hepatitis C virus (HCV), which has been identified in a patient. When the derivative of fluorescence was plotted versus the temperature for the patient's isolate as well as for a known genotype of HCV, the two sequences had identical peaks and thus the same T_m. Which of the following is the correct interpretation of these results?

A) The patient's HCV genotype is the same as the known genotype.
B) The patient's HCV genotype is different from the known genotype.
C) The patient has multiple HCV genotypes.
D) The patient's virus is not HCV but some other virus.

Question 10

Which is a frameshift mutation?

A) Loss of one codon
B) A 3-base insertion
C) A 6-base deletion
D) A 2-base deletion

Question 11

Which of the following mutations is more likely to result in a phenotypic change?

A) Frameshift mutation at the beginning of the coding sequence
B) Nonconservative mutation at the end of the coding sequence
C) Silent mutation in the middle of the coding sequence
D) Conservative mutation at the end of the coding sequence

Question 12

Which is critical to the success of sequence-specific PCR?

A) The 5 end of the primer must match the template.
B) The forward primer must have a higher Tm than the reverse primer.
C) The 3 base of the primer must be complementary to the template.
D) The primers must be less than 20 bases long.

Question 13

The codon UGG is mutated to UGA. What will happen to the encoded protein?

A) The encoded protein will be larger than the protein encoded by the original sequence.
B) The encoded protein will be prematurely terminated.
C) The encoded protein will be more hydrophilic.
D) The encoded protein will not be affected.

Question 14

Patient DNA has been mixed in separate wells with a probe that detects the 1691G>A mutation associated with factor V Leiden and a probe that detects the normal sequence. Cleavase is added to all wells, and the fluorescence is measured in each well. Fluorescence was detected in the well that included the normal probe, and no fluorescence was detected in the well containing the mutant probe. Which of the following assays was performed?

A) Invader assay
B) Nonisotopic RNase cleavage assay
C) Chemical cleavage assay
D) High-density oligonucleotide array

Question 15

Which of the following describes size-exclusion HPLC?

A) Porous beads trap smaller molecules and exclude larger ones.
B) Tiny beads trap larger molecules and exclude smaller ones.
C) Molecules are retained by immobilized charged groups.
D) Particles are resolved in an inert gas mobile phase.

Question 16

ELISA is based on what earlier method first used to detect insulin in plasma?

A) PCR
B) Northern blot
C) RIA
D) EIA

Question 17

A patient is being tested to determine whether he has the factor V Leiden mutation by PCR-RFLP analysis. PCR is performed on the patient's DNA and cut with HindIII. The mutation-positive control sample had a single band of expected size, and the mutation-negative control sample had a slightly larger band. The patient's specimen had two bands, one that was the same size as the mutation-positive control band and the other the same as the mutation-negative control. Which of the following is the correct interpretation of these results?

A) The patient does not have the factor V Leiden mutation.
B) The patient is heterozygous for the factor V Leiden mutation.
C) The patient is homozygous for the factor V Leiden mutation.
D) The results are not valid, and the assay should be repeated.

Question 18

Which of the following methods has the highest sensitivity, specificity, and accuracy as far as detecting DNA mutations in clinical applications?

A) ELISA
B) High-density oligonucleotide array
C) PCR-RFLP
D) Single-strand conformation polymorphism

Question 19

What is MALDI-TOF?

A) An HPLC method
B) Gel-based electrophoresis
C) A type of mass spectrometry
D) ELISA performed under controlled conditions

Question 20

Which of the following methods used to detect mutations is a sequencing (polymerization)-based method?

A) Restriction fragment length polymorphisms
B) Single-strand conformation polymorphisms
C) Dideoxy DNA fingerprinting
D) Invader assay

Question 21

The amino acid sequence DAILMNCST has an S8X mutation. Which of the following correctly describes this mutation?

A) Seven additional serine residues are inserted next to S.
B) The S is substituted with any amino acid at position 8.
C) There was a frameshift mutation at the S, producing a stop codon.
D) The S at position 8 is mutated to a nonsense codon.

Question 22

Which of the following methods can be used to screen for the presence of unknown mutations?

A) SSP-PCR
B) Allele-specific oligomer hybridization
C) High-density array
D) PCR-RFLP

Question 23

A reference segment of DNA has the following sequence: GCTCACCATGG. The fourth nucleotide is changed to an A in a particular genetic disease. How would this mutation be denoted?

A) 4C>A
B) 8A>C
C) 4delC
D) C4A

Question 24

A reference segment of DNA has the following sequence: GCTCACCATGG. Insertion of AG occurs between positions 7 and 8 in a particular genetic disease. How is this mutation denoted by accepted nomenclature?

A) 7C>AG
B) 7_8insAG
C) 8delAinsAG
D) 7_8delAG

Question 25

A protein with the sequence DAILMNCST is mutated such that amino acids L and M are deleted. How is this mutation noted by accepted nomenclature?

A) I3_N6del2
B) L4M
C) L4_M5del2
D) L4NfsX9