Deck 11: Genetics of Cancer

Question 1

Karyotype analysis

A) is a surgical technique that separates chromosomes that have failed to segregate properly during meiosis.
B) is used in prenatal diagnosis to detect chromosomal mutations and metabolic disorders in embryos.
C) substitutes defective alleles with normal ones.
D) is a means of detecting and reducing mutagenic agents.
E) None of these

Answer 1

B

Question 2

Which of the following is a sex-linked disorder?

A) Alkaptonuria
B) Tay-Sachs disease
C) Lesch-Nyhan syndrome
D) Down syndrome
E) Albinism

Answer 2

C

Question 3

What does a gene actually code for?

A) A polypeptide
B) An amino acid
C) A protein
D) An enzyme
E) A nucleotide

Answer 3

A

Question 4

The cystic fibrosis gene-CFTR-codes for a protein that is essential for

A) secretion of mucus.
B) transport of oxygen in red blood cells.
C) metabolism of certain amino acids.
D) ion transport across membranes.
E) processing of gangliosides.

Question 5

Among Caucasians, the most common lethal autosomal recessive disease is

A) hemophilia.
B) muscular dystrophy.
C) cystic fibrosis.
D) sickle-cell disease.
E) phenylketonuria.

Question 6

Lesch-Nyhan syndrome individuals exhibit

A) severe anemia.
B) a cherry-colored spot on the retina.
C) compulsive self-mutilation behaviors.
D) lighter than normal pigmentation of skin, hair, and eyes.
E) urine that turns black when exposed to air.

Question 7

A person with sickle-cell trait has ________ at the beta-globin locus.

A) one mutant and one deleted allele
B) two wild-type alleles
C) two mutant alleles
D) one wild-type and one deleted allele
E) one wild-type and one mutant allele

Question 8

In people who do not have Tay-Sachs disease, the hexA gene encodes an enzyme that

A) removes a sugar group from phenylalanine.
B) cleaves acetylgalactosamine from gangliosides.
C) synthesizes glycogen from glucose monomers.
D) converts tyrosine into melanin in skin.
E) converts purines to uric acid in the kidneys.

Question 9

A lysosomal storage disease is a disease caused by

A) failure of the cell to produce lysosomes.
B) an excess in the production of lysosomic digestive enzymes.
C) mutations in genes for lysosomic membrane proteins.
D) the inability to synthesize glycolipids.
E) mutations in genes that code for lysosomic digestive enzymes.

Question 10

Cystic fibrosis is caused by a mutation in the gene that encodes which enzyme?

A) Pyruvate kinase
B) Hemoglobin
C) Tyrosine kinase
D) CFTR protein
E) Hexosaminidase A

Question 11

The synthesis of cellular components typically occurs via biochemical pathways involving

A) the simultaneous synthesis of all intermediate molecules.
B) a single enzymatic reaction.
C) a series of small steps, each catalyzed by an enzyme.
D) the accumulation of a blocked intermediate in the pathway.
E) the simultaneous activity of several enzymes.

Question 12

A person with PKU

A) can manage the disorder through dietary means.
B) converts phenylalanine to tyrosine.
C) may be characterized by mental retardation.
D) has dark skin due to an accumulation of the skin pigment melanin.
E) Both C and D

Question 13

Which genetic disease(s) are caused by defective proteins that are not enzymes?

A) Tay-Sachs disease and phenylketonuria
B) Albinism and alkaptonuria
C) Lesch-Nyhan syndrome.
D) Sickle-cell anemia and cystic fibrosis
E) All of these

Question 14

In a molecule of hemoglobin C, an aspartic acid residue is changed into a ________ residue.

A) tyrosine
B) phenylalanine
C) glutamine
D) lysine
E) leucine

Question 15

Cystic fibrosis is an autosomal recessive disorder. What is the chance that two carrier parents will have an affected child?

A) 75 percent
B) 100 percent
C) 0 percent
D) 50 percent
E) 25 percent

Question 16

A mutation that has pleiotropic consequences

A) results in a single symptom in the affected person.
B) has widespread consequences in the affected person.
C) cannot be detected by enzyme assay.
D) is only detected in homozygotes.
E) may result in only slight symptoms in a person with the mutation.

Question 17

What was the significance of the Beadle and Tatum experiment?

A) It resulted in the Central Dogma.
B) It led to the discovery of bread mold.
C) It showed that X-rays were mutagens.
D) It resulted in the one-gene-one-enzyme hypothesis.
E) It led to the discovery of the genetic code.

Question 18

What does Garrod's hypothesis indicate?

A) Human cells contain 23 pairs of chromosomes.
B) Enzymes are made of proteins.
C) DNA is found in the nucleus of eukaryotic cells.
D) There is a link between genes and enzymes.
E) Genes are made of DNA.

Question 19

Amniocentesis involves

A) taking a sample of amniotic fluid with a needle.
B) analysis for DNA and chromosome defects in a fetus.
C) prenatal diagnosis of genetic defects in a fetus.
D) tests for enzyme and protein deficiencies in a fetus.
E) all of the above.

Question 20

The difference between normal and sickle-cell hemoglobin is based upon

A) the number of amino acids in the molecule.
B) the type of bone marrow that produces it.
C) the number and orientation of the amino acid chains attached to the heme portion of the molecule.
D) the number of oxygen molecules that can be carried.
E) a single DNA point mutation leading to the substitution of one amino acid for another.

Question 21

Tay-Sachs is a lysosomal storage disease.

Question 22

Why are genetic diseases much more common among children of marriages involving first cousins than among children of marriages between unrelated partners?

Question 23

The Guthrie test screens for excessive phenylalanine in the blood of infants.

Question 24

Sickle-cell disease is more common among people who are of African descent than those who are Caucasian.

Question 25

The following is a representation of a metabolic pathway involving genes for enzymes A, B, C, and D: A→B→C→D→product A mutation in the "B" gene would result in an accumulation of which gene product?

Question 26

A person who is homozygous for the gene for hemoglobin A will have sickle-cell disease.

Question 27

How do scientists, lacking the ability to make controlled genetic crosses in humans, study the inheritance of and give genetic counseling on human genetic disorders?

Question 28

How are the diseases PKU, albinism, and alkaptonuria all related?

Question 29

Because Lesch-Nyhan syndrome is a recessive X-linked disease, females who have an allele with the mutation responsible for this disease are generally symptom-free.

Question 30

Classic albinism is an autosomal recessive mutation, yet two albino parents may produce a child with normal pigment. How can this be so?

Question 31

What is an inborn error of metabolism? Give an example.

Question 32

A Neurospora mutant that is a tryptophan auxotroph should be grown on a medium that contains all amino acids but tryptophan.

Question 33

A person with PKU controls the buildup of phenylpyruvic acid in their blood by restricting their dietary intake of phenylalanine, thus avoiding the severe symptoms of mental retardation, slow growth rate, and early death. Yet, she still exhibits the symptoms of fair skin and low adrenaline levels. Why?

Question 34

You discover a mutant strain of Neurospora crassa that will not grow on a minimal medium but that will grow on a medium supplemented by the amino acid methionine. How can you determine which step in the methionine synthesis pathway is affected by the mutation?

Question 35

Genetic counseling is the best advice a physician can give a person about their risk of having a child with a genetic disorder while lacking precise statistical evidence.

Question 36

What is an essential amino acid? Give an example.

Question 37

Cystic fibrosis is caused by a single point mutation in a gene for a membrane protein, causing loss of protein function.

Question 38

In the lab, how could you distinguish between normal hemoglobin A and hemoglobin S?

Question 39

The sickle-cell mutant allele and wild-type beta-globin allele are codominant.

Question 40

Whereas the defective gene product in patients with PKU was identified using biochemical analysis, how was cystic fibrosis gene identified?

Question 41

Explain the difference between the one-gene-one-enzyme hypothesis and the one-gene-one-polypeptide hypothesis.

Question 42

You are a doctor specializing in genetic diseases. A married couple comes to see you for genetic counseling. The woman has the disease PKU, the symptoms of which she manages by diet. The man and woman are first cousins and would like to know the probability that any of their children will have the disease. What would you tell them?

Question 43

How can enzyme assay be used to detect a person of normal phenotype who is the carrier of a recessive gene mutation?

Question 44

What are some advantages to chorionic villus sampling over amniocentesis for fetal analysis of genetic defects?