Deck 11: Mutation: the Source of Genetic Variation

Question 1

If a mutant allele appears in a family with no history of that disorder and is fully expressed by everyone carrying that allele, it most like is a ______________ allele.

A) autosomal dominant
B) autosomal recessive
C) X-linked recessive
D) Y-linked
E) mitochondrial

Answer 1

A

Question 2

Which of the following does NOT affect the mutation rate of a gene?

A) The size of the gene.
B) The number of GC pairs versus AT pairs.
C) Whether the gene is on a maternal or paternal chromosome.
D) The number of trinucleotide sequences.
E) All of these affect the mutation rate of a gene.

Answer 2

C

Question 3

The largest source of radiation people are exposed to in the United States is from _____________.

A) medical X-rays
B) cosmic rays
C) consumer products
D) radon
E) nuclear medicine

Answer 3

D

Question 4

Fragile-X syndrome is an example of a disorder caused by trinucleotide repeats.

Question 5

Which one of the following statements about genomic imprinting is FALSE?

A) The DNA changes involved are reversible.
B) It is considered an "epigenetic" change.
C) It can occur in any gene.
D) It takes place during gamete formation or early embryonic development.
E) It affects the expression of a gene, not the gene itself.

Question 6

Which of the following could result in the most serious type of mutation?

A) A nucleotide substitution in an exon.
B) A nucleotide deletion in an exon.
C) A nucleotide insertion in an intron.
D) A nucleotide substitution in an intron.
E) More than one of these would be most serious.

Question 7

A mutation occurs that changes a C to a T in DNA such that, in the mRNA transcribed from this piece of DNA, a UGG codon is changed to UGA. This mutation is a

A) substitution mutation.
B) missense mutation.
C) nonsense mutation.
D) substitution mutation and a missense mutation.
E) substitution mutation and a nonsense mutation.

Question 8

For the average person in the U.S., the largest source of radiation exposure is

A) background radiation.
B) medical X-rays.
C) irradiated food.
D) consumer products.
E) remote-controlled devices.

Question 9

Queen Victoria had an allele for alkaptonuria that originated by mutation in one of her parents.

Question 10

Thymine can be converted to uracil by a chemical mutagen.

Question 11

Thymine dimers

A) involve mutations in purines.
B) involve adjacent nucleotides in the DNA.
C) result from exposure to chemicals.
D) do not alter the structure of DNA.
E) are formed by exposure to hydroxyurea.

Question 12

In pedigree analysis, it is easiest to identify the individual most likely to be the source of the mutation if the mutation is

A) mitochondrial.
B) recessive.
C) autosomal dominant.
D) sex-linked recessive.
E) pseudoautosomal.

Question 13

Which of the following elements, when added to a nucleotide base, will create a base analog?

A) Carbon
B) Oxygen
C) Bromine
D) Boron
E) Phosphorous

Question 14

____________ mutations are the underlying cause of most types of cancer.

A) X-linked
B) Somatic
C) Viral
D) Y-linked
E) Mitochondrial

Question 15

All chromosomally normal individuals have an equal number of autosomes from each parent.

Question 16

Which of the following will occur to a cell that undergoes a critical amount of mutational damage?

A) It will enter into senescence.
B) Apoptosis will occur.
C) It will become cancerous.
D) A and C will occur but not
E) All three will occur (A, B, and C).

Question 17

Julie has pigmented spots and tumors on her skin and nervous system. It is determined the disease Julie has is autosomal dominant. Julie most likely has _____________.

A) hemophilia
B) neurofibromatosis
C) achondroplasia
D) Marfan syndrome
E) fragile-X syndrome

Question 18

Some genes with a number of trinucleotide repeats significantly above normal produce a mutant phenotype.

Question 19

In a missense mutation:

A) All the amino acids beyond the mutation point are changed.
B) A nucleotide is added to the DNA.
C) A nucleotide is deleted from the DNA.
D) A single amino acid is altered.
E) The protein is always completely nonfunctional.

Question 20

Mutation rates of human genes are usually expressed as the number of

A) nucleotides altered per gene.
B) frameshift mutations per genome.
C) mutated alleles per genome.
D) mutant births per generation.
E) mutated alleles per generation.

Question 21

Fragile-X syndrome is an example of a genetic condition caused by a frameshift mutation.

Question 22

____________________ are mutations involving the increase of the number of repeat sequences in genes.

Question 23

Radiation from natural sources (as opposed to sources resulting from human activity) is called ____________________ radiation.

Question 24

The ability of DNA polymerase to repair its own nucleotide mismatches is called ____________________.

Question 25

Addition or deletion of a nucleotide in a gene causes a type of mutation called a ____________________.

Question 26

It is possible to have a mutation in a gene that produces no change whatsoever in the protein coded for by that gene.

Question 27

A radiation dose of 400 rem, if untreated, causes death within 60 days of about ____________________ percent of people exposed to it.

Question 28

All genes on all human chromosomes are subject to imprinting.

Question 29

A ____________________ heterozygote is an individual with two different mutant alleles of a gene.

Question 30

Genes with large numbers of _____________ base pairs are more likely to have a higher mutation rate than genes with large numbers of ___________ base pairs.

Question 31

In disorders caused by multiple trinucleotide repeats, the more repeats there are the later the symptoms of the disorder become manifested.

Question 32

Genomic imprinting is a phenomenon that does not violate Mendelian principles of segregation and independent assortment.

Question 33

Sickle cell anemia is caused by a missense mutation.

Question 34

Frameshift mutations include nucleotide substitutions.

Question 35

Common foods that we eat may contain mutagens.

Question 36

The appearance of symptoms of a genetic disorder at earlier ages in succeeding generations is ____________________.

Question 37

Chemicals that resemble base pairs and insert themselves into DNA molecules are called ____________________ agents.

Question 38

Nonsense mutations are mutations caused by nucleotide substitutions that change one amino acid into another.

Question 39

The differential expression of genes depending on parental origin is called ____________________.

Question 40

Genomic imprinting is caused by epigenetic changes to DNA

Question 41

In diseases like xeroderma pigmentosum, why is it that mutations in several different genes can produce the same phenotypic effect?

Question 42

A mutation that would change an amino acid coding codon into a termination codon is called a _____________ mutation.

Question 43

Why is it easier to detect the formation of sex-linked recessive mutations than autosomal recessive mutations?

Question 44

Explain why individuals with cystic fibrosis may have different levels of severity of the disease.

Question 45

How are thymine dimers generated? What are their effects and how are they handled by the cell?

Question 46

Explain how a deficiency in the chromosomal contribution of one parent might be compensated for by an excess in the contribution of the other parent.

Question 47

Describe three ways that DNA mutations can alter the protein product.

Question 48

Compare the effects of nonsense mutations, sense mutations, nucleotide substitutions, and frameshift mutations on protein synthesis.

Question 49

Why do some genetic disorders have a high new mutation rate (hemophilia and muscular dystrophy) while others display a very low new mutation rate (Huntington's disease)?

Question 50

A purine or pyrimidine that differs in chemical structure from a purine or pyrimidine normally found in DNA or RNA is called a _____________.

Question 51

A protein encoding region of a gene has the following DNA sequence: GTAGCGTCACAAACAAATCAGCTC. Determine how the final protein product would be altered by each of the following mutations.
a. Substitution of a T for the C in the 10th base.
b. Substitution of a G for the C in the 21st base.
c. Insertion of a T between the fourth and fifth base.
d. Insertion of a GTA between the 12th and 13th base.
e. Deletion of the first base.

Question 52

The change of the pattern of gene expression without changing the nucleotide sequence of DNA is termed _________________.

Question 53

Occasionally, individuals have eyes of different colors. How would you explain this mutation? Do you think it is heritable?

Question 54

The base analog, 5-bromouracil substitutes for the nucleotide base, _____________, in a DNA molecule.

Question 55

Describe the DNA mutation in fragile-X syndrome and how it changes from generation to generation.

Question 56

The chemical group associated with epigenetic changes to our genome is the _________ group.

Question 57

Explain why the phenomena of anticipation and genomic imprinting seemed at first, before they were understood, to violate basic concepts of Mendelian genetics.