Chapter 15: Gene Mutation and Molecular Medicine

1. Mutations are
a. heritable changes in the sequence of DNA bases that produce an observable phenotype.
b. changes in the nucleotide sequence of DNA that is passed on from one organism to another.
c. mistakes in the incorporation of amino acids into proteins.
d. heritable changes in the mRNA of an organism.
e. None of the above
2. Somatic and germ line are two types of mutations found in multicellular organisms. Which of the following is a true statement regarding these two types of mutations?
a. Somatic mutations occur during sex cell formation.
b. Germ line mutations occur during mitosis.
c. Somatic mutations are passed on to sexually produced offspring.
d. An example of a germ line mutation is hemophilia.
e. All of the above
3. In sickle-cell disease, one amino acid is substituted for another. This type of mutation is referred to as a _______ mutation.
a. nonsense
b. missense
c. frame-shift
d. temperature sensitive
e. silent
4. Silent mutations have no effect on amino acid sequences. This is due to the fact that
a. silent mutations are usually found in noncoding regions of DNA.
b. the genetic code is ambiguous.
c. silent mutations are recessive, and the presence of the dominant allele will result in a functional protein.
d. silent mutations are conditional mutagens, and their phenotypes are only altered under very restrictive conditions.
e. only a single base is involved in a series of thousands of nucleotides.
5. The type of mutation that involves the insertion or a deletion of a single base in the coding region of proteins is called
a. a missense mutation.
b. a nonsense mutation.
c. a point mutation.
d. an aberration.
e. None of the above
6. People with sickle-cell disease have _______ abnormality.
a. a phenylalanine hydrolyase
b. an oncogene
c. a cholesterol transport
d. a hemoglobin
e. None of the above
7. _______ is caused by a single base substitution that changes one amino acid in a polypeptide. Individuals who are homozygous for this disease have defective, misshapen red blood cells.
a. Duchenne muscular dystrophy
b. Sickle-cell anemia
c. Kuru
d. Cystic fibrosis
e. Familial hypercholesterolemia
8. Single base changes in the coding regions of proteins can cause
a. missense mutations.
b. nonsense mutations.
c. frame-shift mutations.
d. silent mutations.
e. All of the above
9. An example of a gain of function missense mutation is a mutation of the TP53 gene. Normally, this protein inhibits cell division, but certain mutations in the TP53 gene
a. result in a gain of an oncogenic (cancer-causing) function.
b. do not result in a change in the amino acid sequence.
c. cause the protein to stop translation and no protein is made at all.
d. cause thymine to form covalent bonds with adjacent bases.
e. result in nondisjunction.
10. Breaking and rejoining of chromosomes can lead to
a. deletions.
b. duplications.
c. inversions.
d. translocations.
e. All of the above
11. The type of mutation that stops translation of a protein results in a shortened protein because translation does not proceed beyond the mutation. An example is thalassemia, which is
a. a missense mutation.
b. a nonsense mutation.
c. a frame-shift mutation.
d. an aberration.
e. None of the above
12. Duplications and translocations differ in that
a. translocations involve the loss of a chromosomal segment, whereas duplications involve addition of an entire chromosome.
b. duplications involve the breakage and swapping of DNA segments on homologous chromosomes, whereas translocations are reciprocal exchanges on nonhomologous chromosomes.
c. translocations involve the breakage and insertion of DNA segments in reverse order, whereas duplications are the breakage at different points on the chromosome.
d. duplications lead to duplications of the chromosome, whereas translocations involve swapping of chromosome segments.
e. translocations result in loss of chromosomal segments, whereas duplications result in significant additions to nonhomologous chromosomes.
13. Spontaneous mutations may be caused by all of the following except
a. a base, in its tautomer form, pairing incorrectly.
b. deamination, causing mismatched base pairs.
c. DNA polymerase making errors in base pairings.
d. free radicals changing the base structure so it is unrecognizable by DNA polymerase.
e. an occurence of nondisjunction.
14. Benzopyrene, a component of cigarette smoke, can induce DNA mutations by
a. converting cytosine to uracil by deamination.
b. converting an amino group on cytosine into a keto group.
c. adding a chemical to guanine, making it unavailable for base pairing.
d. changing bases to forms unrecognizable by DNA polymerase.
e. breaking the sugar-phosphate backbone of DNA.
15. Damage to DNA can be caused by _______ absorbed by thymine in DNA, causing interbase covalent bonds.
a. X rays
b. cosmic radiation
c. ultraviolet radiation
d. smoke
e. cigarettes
16. Mutational "hot spots" often occur when a methyl group has been added to
a. adenine.
b. cytosine.
c. guanine.
d. thymine.
e. uracil.
17. Among the human genome's 2.3 billion base pairs, there are about 16,000 DNA-damaging events daily. About what percentage is repaired?
a. 10 percent
b. 25 percent
c. 50 percent
d. 60 percent
e. 80 percent
18. Nitrites, a human-made preservative for meats, and aflatoxin, a natural product produced by the mold Aspergillus, are similar in that
a. they are converted by the endoplasmic reticulum into a mutagenic substance.
b. they readily lose an amine group to form a unique nitrogenous base.
c. their unmethylated cytosine loses its amino group to form uracil.
d. their thymine bases form covalent bonds with adjacent bases.
e. ultraviolet light distorts their DNA double helix, which interferes with translation.
19. The rates of DNA mutations are _______ in different organisms.
a. the same
b. constant
c. different
d. dependent on health
e. dependent on temperature
20. Which of the following enzymes are used by bacteria to defend themselves against bacteriophage?
a. DNA polymerase
b. Reverse transcriptase
c. Phosphofructokinase
d. Restriction endonuclease
e. None of the above
21. Most restriction sites are _______ base pairs long.
a. 1 or 2
b. 4 to 6
c. about 10
d. about 20
e. over 50
22. Which of the following enzymes would a bacterium most likely use to prevent its DNA from being chopped up by its own restriction enzymes?
a. DNA polymerase
b. Ligase
c. Lactase
d. Reverse transcriptase
e. Methylase
23. Restriction enzymes cleave DNA at specific sequences by hydrolyzing
a. the 3´ hydroxyl of one nucleotide and the 5´ phosphate of the next one.
b. at the 1´ carbons to cleave the nitrogenous bases.
c. at the 2´ carbons to cleave hydroxyl groups.
d. two phosphodiester linkages on the same strand.
e. four phosphodiester linkages, two on each strand.
24. Which of the following is true about restriction enzymes?
a. They cut at regular intervals, every 4,000 base pairs.
b. They prefer to cut at DNA that has been methylated.
c. EcoRI's restriction site is a palindrome.
d. All of the above
e. None of the above
25. Which of the following is a palindromic recognition sequence?
a. 5´. . . CAATAG . . . 3´
b. 5´. . . CAATTG . . . 3´
c. 5´. . . CATTTG . . . 3´
d. 5´. . . GATTTC . . . 3´
e. 5´. . . CATCAT . . . 3´
26. DNA, because it has a _______ charge, moves to the _______ end of the field in gel electrophoresis; _______ DNA molecules migrate the most quickly.
a. positive; positive; smaller
b. positive; positive; larger
c. positive; negative; smaller
d. negative; positive; larger
e. negative; positive; smaller
27. A single hair is found at the scene of a crime. Which technology would you use first to determine if the hair could have come from a certain suspect?
a. PCR
b. DNA sequencing
c. Fragment cloning
d. Probing
e. Antisense RNA
28 DNA is _______ charged due to the presence of a _______ group.
a. negatively; methyl
b. negatively; phosphate
c. negatively; carbon
d. positively; methyl
e. positively; phosphate
29. Electrophoresis separates DNA fragments of different sizes, but this technique does not indicate which of the fragments contains the DNA piece of interest. This problem is solved by
a. measuring the sizes of the bands on the gel.
b. removing the bands from the gel and hybridizing them with a known strand of DNA complementary to the gene of interest.
c. knowing the isoelectric points of the piece in question.
d. identifying the molecular weights of the fragments in question.
e. None of the above
30. Which of the following types of variations would be most detectable by gel electrophoresis if the differences in the DNA were between two recognition sites for a restriction enzyme?
a. SNPs
b. PCRs
c. HMRs
d. STRs
e. HMOs
31. Which of the following statements is true regarding short tandem repeats (STRs)?
a. STRs are short, repetitive DNA sequences.
b. STRs occur side by side on chromosomes.
c. STRs usually occur in noncoding regions.
d. STRs contain 1-5 base pairs.
e. All of the above
32. Which of the following types of variation involves changes at a single nucleotide base?
a. SNPs
b. PCRs
c. HMRs
d. STRs
e. HMOs
33. Which two methods are most often used in DNA fingerprinting?
a. Homologous and antisense RNA recombination
b. Pharming and phishing
c. Restriction digestion and gel electrophoresis
d. Gel electrophoresis and creation of expression vectors
e. Homologous recombination and the construction of gene libraries
34. Which of the following statements about DNA fingerprinting is true?
a. To date, DNA fingerprinting has been used forensically to prove guilt more often than it has been used to prove innocence.
b. DNA fingerprinting cannot be used on skeletons over 50 years old.
c. DNA fingerprinting examines just a small fraction of the genome.
d. All of the above
e. None of the above
35. Which of the following statements regarding short tandem repeats (STRs) is false?
a. STRs are inherited.
b. STRs are the result of a single nucleotide base mutation.
c. The FBI uses 13 STR loci in its CODIS database to solve crimes.
d. STRs were used to confirm the execution of Tsar Nicholas II and his family.
e. DNA fingerprinting usually involves STR analysis.
36. Paul Hebert proposed using cytochrome oxidase in the DNA barcode project because it
a. evolves slowly.
b. mutates readily.
c. is found in most organisms.
d. Both a and c
e. Both b and c
37. The DNA barcode project has the potential to
a. track species diversity in important ecological areas.
b. advance research in evolutionary biology.
c. detect undesirable microbes in food.
d. All of the above
e. None of the above
38. Genetic mutations are often expressed phenotypically as
a. dysfunctional enzymes.
b. abnormal receptor proteins.
c. abnormal transport proteins.
d. abnormal structural proteins.
e. All of the above
39. Individuals with PKU have an abnormal
a. lipoprotein.
b. prion.
c. triplet repeat.
d. oncogene.
e. enzyme.
40. People with PKU often have too much of the amino acid _______ and too little of the amino acid _______.
a. phenylalanine; alanine
b. phenylalanine; tyrosine
c. tyrosine; phenylalanine
d. tyrosine; alanine
e. alanine; tyrosine
41. The primary consequence of untreated phenylketonuria is
a. muscle atrophy.
b. kidney failure.
c. mental retardation.
d. skeletal problems.
e. None of the above
42. What is the most likely explanation for the light skin and hair of people with PKU?
a. Too much phenylalanine interferes with the production of melanin.
b. Their expression levels of the genes that produce melanin are low.
c. They cannot adequately synthesize tyrosine, an important precursor of melanin.
d. Melanin is broken down by excess phenylalanine.
e. Phenylalanine interferes with the transport of melanin to the appropriate location.
43. People with sickle-cell disease have a(n) _______ abnormality.
a. phenylalanine hydrolyase
b. oncogene
c. cholesterol transport
d. hemoglobin
e. None of the above
44. Sickle-cell disease is an inherited disease caused by an alteration of a single amino acid in a protein. Specifically,
a. the sixth amino acid, glutamic acid, is replaced by valine.
b. the sixth amino acid, glutamic acid, is replaced by lysine.
c. the charge of the protein is changed, which causes the protein to change shape.
d. Both a and c
e. Both b and c
45. Which of the following diseases results from an improperly functioning receptor protein?
a. Sickle-cell anemia
b. PKU
c. Hemophilia
d. BSE
e. Familial hypercholesterolemia
46. Which of the following statements about prion diseases is true?
a. They are caused by viruses.
b. They cannot be transmitted between different species.
c. An abnormal protein can infect and cause disease by altering the normal structure of a protein, causing the normal protein to assume an abnormal three-dimensional structure.
d. The disease almost always manifests itself within weeks of infection.
e. They are not found in humans.
47. Stanley Prusiner received a Nobel Prize for
a. showing that some oncogenes are transcription factors.
b. purifying the protein responsible for TSEs and showing that no nucleic acids were involved in the infectiousness of prion diseases.
c. discovering the protein responsible for cystic fibrosis.
d. sequencing the human genome with shotgun sequencing.
e. demonstrating that expanding triplet repeats are responsible for some diseases.
48. "Mad cow disease" is most likely due to
a. an alteration in protein conformation.
b. a change in the amino acid sequences of a protein.
c. a missing protein.
d. the number of triplet repeats of a protein.
e. Both a and b
49. The molecular basis of which of the following human diseases is most similar to "mad cow disease"?
a. Sickle-cell anemia
b. Huntington's disease
c. Duchenne muscular dystrophy
d. Alzheimer's disease
e. Fragile-X syndrome
50. An RFLP
a. is a restriction fragment length polymorphism.
b. is inherited in a Mendelian fashion.
c. can be used as a genetic marker.
d. can be useful to help define a discrete gene.
e. All of the above
51. Genetic markers must be polymorphic. Why is polymorphism an important characteristic of genetic markers?
a. The various phenotypes help to identify the actual gene responsible for a genetic disease.
b. Polymorphisms provide biochemical and physiological information about the disease.
c. Knowledge of the gene sequence allows for identification of the protein.
d. Radioactive labels can be added for easy identification of the disease.
e. They can be easily visualized as bands on an electrophoresis gel.
52. Which of the following statements about fragile-X syndrome is true?
a. It affects more women than men.
b. Nearly all people with the fragile-X chromosomal abnormality are mentally retarded.
c. Individuals with more triplet repeats are less likely to get the disease.
d. In families with fragile-X syndrome, later generations tend to show more and more severe symptoms of the disease.
e. None of the above
53. In fragile-X syndrome, males are said to be _______; grandchildren from their daughters have _______ repeats than their daughters have.
a. imprinted; more
b. imprinted; fewer
c. premutated; more
d. premutated; fewer
e. multifactorial; more
54. Excess numbers of the CGG triplets in the FMR1 gene lead to clinical symptoms, including mental retardation, because the
a. triplets bind to mRNAs of other genes.
b. cytosines in the repeats are more likely to be methylated, leading to inactivation of the gene.
c. triplets cause genomic imprinting.
d. triplets make the gene so large that its mRNA cannot be transported properly.
e. triplets cause the protein to fold incorrectly.
55. Expanding repeats have been found in several diseases. How do expanding repeats cause a disease?
a. All the codons are translated, causing a malfunctioning of the cell.
b. It increases methylation of the adenines, which stops transcription.
c. DNA polymerase is not able to properly attach to the promoter to start translation.
d. The repeats interfere with translation of normal mRNAs.
e. They cause a frame-shift mutation.
56. A genetic disease that is caused by a deletion in the X chromosome is
a. sickle-cell disease.
b. hemophilia.
c. Duchenne muscular dystrophy.
d. PKU.
e. Both a and b
57. The test developed in 1963 to screen newborns for PKU
a. involves positional cloning.
b. uses PCR and RFLPs to examine their DNA.
c. tests for the level of phenylalanine in their blood.
d. requires constructing a gene library.
e. None of the above
58. Which of the following techniques relies on the same principle as RFLP?
a. Amniocentesis
b. Screening by allele-specific oligonucleotide hybridization
c. Screening by allele-specific cleavage
d. Guthrie's test for PKU
e. Preimplantation screening
59. Which of the following statements is true regarding allele-specific oligonucleotide hybridization?
a. It uses oligonucleotide probes.
b. A minimum of a dozen bases is required.
c. The probe may be radioactive or fluorescent so hybridization can be easily detected.
d. It can reveal whether individuals are heterozygous.
e. All of the above
60. Which of the following treatments involves restricting the substrate?
a. Use of statin drugs to reduce cholesterol
b. Giving children with PKU Lofenalac instead of formula
c. Chemotherapy treatment with 5-fluorouracil
d. Chemotherapy treatment with arabinocytosine
e. Chemotherapy treatment with Taxol
61. Ingesting which of the following would be safest for a person with PKU?
a. Dietary products
b. Diet drinks with aspartame
c. Bread
d. Lofenalac
e. Fish
62. In one type of cancer, myelogenous leukemia, certain white blood cells undergo a gain-of-function mutation resulting in a totally new protein. The treatment involves
a. supplying the correct protein intravenously.
b. using molecular medicine to produce a drug to inactivate the protein.
c. using gene therapy to insert a new gene to supply the correct protein.
d. radiation and chemotherapy.
e. administrating large doses of adenosine deaminase.
64. For gene therapy to be successful,
a. the new sequence of DNA must become part of the patient's genome.
b. the gene must be precisely inserted into the patient's cells.
c. the gene must be attached to a promoter that will express it.
d. Both a and b
e. a, b, and c