Deck 15: Gene Mutation and Molecular Medicine

Question 1

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

Answer 1

D

Question 2

_______ 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

Answer 2

B

Question 3

Breaking and rejoining of chromosomes can lead to

A) deletions.
B) duplications.
C) inversions.
D) translocations.
E) All of the above

Answer 3

E

Question 4

Newborn genetic screening for PKU

A) is very expensive.
B) detects phenylketones in urine.
C) has not led to the prevention of mental retardation resulting from this disorder.
D) should be done during the second or third day of an infant's life.
E) uses bacterial growth to detect excess phenylketones in blood.

Question 5

Mutations of the gene for $\beta$ -globin

A) are usually lethal.
B) occur only at amino acid position 6.
C) number in the hundreds.
D) always result in sickling of red blood cells.
E) can always be detected by gel electrophoresis.

Question 6

Mutational "hot spots" in human DNA

A) always occur in genes that are transcribed.
B) are common at cytosines that have been modified to 5-methylcytosine.
C) involve long stretches of nucleotides.
D) occur only where there are long repeats.
E) are very rare in genes that code for proteins.

Question 7

Phenylketonuria is an example of a genetic disease in which

A) a single enzyme is not functional.
B) inheritance is sex-linked.
C) two parents without the disease cannot have a child with the disease.
D) mental retardation always occurs, regardless of treatment.
E) a transport protein does not work properly.

Question 8

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

Question 9

Most genetic diseases are rare because

A) each person is unlikely to be a carrier for harmful alleles.
B) genetic diseases are usually sex-linked and so uncommon in females.
C) genetic diseases are always dominant.
D) two parents probably do not carry the same recessive alleles.
E) mutation rates in humans are low.

Question 10

Genetic diagnosis by DNA testing

A) detects only mutant and not normal alleles.
B) can be done only on eggs or sperm.
C) involves hybridization to rRNA.
D) often utilizes restriction enzymes and a polymorphic site.
E) cannot be done with PCR.

Question 11

In fragile-X syndrome,

A) females are affected more severely than males.
B) a short sequence of DNA is repeated many times to create the fragile site.
C) both the X and Y chromosomes tend to break when prepared for microscopy.
D) all people who carry the gene that causes the syndrome are mentally retarded.
E) the basic pattern of inheritance is autosomal dominant.

Question 12

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

Question 13

Which of the following is not a way to treat a genetic disease?

A) Inhibiting a harmful biochemical reaction
B) Adding the wild-type allele to cells expressing the mutation
C) Restricting the substrate of a harmful biochemical reaction
D) Replacing a mutant allele with the wild-type allele in the fertilized egg
E) Supplying a wild-type protein that is missing due to mutation

Question 14

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

Question 15

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

Question 16

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.

Question 17

Current treatments for genetic diseases include all of the following except

A) restricting a dietary substrate.
B) replacing the mutant gene in all cells.
C) alleviating the patient's symptoms.
D) inhibiting a harmful metabolic reaction.
E) supplying a protein that is missing.

Question 18

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.

Question 19

Multifactorial (complex) diseases

A) are less common than single-gene diseases.
B) involve the interaction of many genes with the environment.
C) affect less than 1 percent of humans.
D) involve the interactions of several mRNAs.
E) are exemplified by sickle-cell disease.

Question 20

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

Question 21

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

Question 22

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

Question 23

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

Question 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

Question 25

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

Question 26

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

Question 27

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.

Question 28

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´

Question 29

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

Question 30

Most restriction sites are _______ base pairs long.

A) 1 or 2
B) 4 to 6
C) about 10
D) about 20
E) over 50

Question 31

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.

Question 32

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.

Question 33

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.

Question 34

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.

Question 35

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

Question 36

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

Question 37

The rates of DNA mutations are _______ in different organisms.

A) the same
B) constant
C) different
D) dependent on health
E) dependent on temperature

Question 38

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

Question 39

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

Question 40

Mutational "hot spots" often occur when a methyl group has been added to

A) adenine.
B) cytosine.
C) guanine.
D) thymine.
E) uracil.

Question 41

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

Question 42

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

Question 43

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

Question 44

"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

Question 45

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

Question 46

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

Question 47

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.

Question 48

Individuals with PKU have an abnormal

A) lipoprotein.
B) prion.
C) triplet repeat.
D) oncogene.
E) enzyme.

Question 49

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

Question 50

People with sickle-cell disease have a(n) _______ abnormality.

A) phenylalanine hydrolyase
B) oncogene
C) cholesterol transport
D) hemoglobin
E) None of the above

Question 51

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.

Question 52

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

Question 53

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.

Question 54

Which of the following types of variation involves changes at a single nucleotide base?

A) SNPs
B) PCRs
C) HMRs
D) STRs
E) HMOs

Question 55

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

Question 56

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.

Question 57

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

Question 58

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

Question 59

The primary consequence of untreated phenylketonuria is

A) muscle atrophy.
B) kidney failure.
C) mental retardation.
D) skeletal problems.
E) None of the above

Question 60

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

Question 61

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.

Question 62

Some bacteria use _______ enzymes as a defense mechanism; these enzymes cut up foreign _______.

Question 63

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

Question 64

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

Question 65

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.

Question 66

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

Question 67

The addition of _______ groups to their DNA is one method used by bacteria to prevent their own DNA from being cut by restriction enzymes.

Question 68

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.

Question 69

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

Question 70

Although there are 6 billion base pairs of DNA packed in 46 human chromosomes, only _______ percent of the DNA in the human genome codes for proteins.

Question 71

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

Question 72

Silent mutations have no effect on amino acid sequences because they are usually found in _______ regions of the DNA.

Question 73

The TP53 gene normally functions to inhibit the cell cycle. If a gain of function missense mutation occurs in the TP53 gene, the mutated TP53 gene will _______ (inhibit or promote) the cell cycle.

Question 74

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

Question 75

Enzymes break the bonds of the DNA backbone between the 3´ hydroxyl group of one nucleotide and the 5´ phosphate group of the next nucleotide. This process is called _______.

Question 76

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

Question 77

Mutations that exhibit the altered phenotype under certain restrictive conditions are referred to as _______ mutations

Question 78

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

Question 79

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.

Question 80

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