Deck 14: Gene Mutation, Dna Repair, and Transposition

Question 1

In general, mutation rates in humans are _.

Answer 1

determined by defining the likelihood that a gene will undergo a mutation in a single generation or in forming a single gamete

Question 2

List five general categories of mutation.

Answer 2

induced, spontaneous, morphological, nutritional/biochemical, behavioral, regulatory, lethal, conditional

Question 3

Which of the following name two mutagens that would be classified as base analogs?

A) hydroxyurea and peroxidase
B) ethylmethane sulfonate and ethylmethylketone peroxide
C) ultraviolet light and cosmic radiation
D) 5 -bromouracil and 2 -amino purine
E) acridine orange and proflavin

Answer 3

D

Question 4

One type of mutation involves the replacement of a purine with a purine, whereas another causes the replacement of a pyrimidine with a purine or the reverse. What general terms are associated with these two mutational phenomena?

Question 5

A class of mutations that results in multiple contiguous amino acid changes in proteins is likely to be which of the following?

A) transversion
B) frameshift
C) transition
D) recombinant
E) base analog

Question 6

Barbara McClintock discovered mobile elements in corn by analyzing the genetic behavior of two elements, Ds and A c. The interplay between these two elements has become one of the most interesting stories of discovery in the field of genetics. How do Ds and Ac interact?

A) Ds moves only if Ac is present in the genome; Ac is capable of autonomous movement.
B) The movement of Ac is dependent on two forms of Ds.
C) Both elements can move only within chromosome 9.
D) Ds causes a deletion next to the insertion site of Ac.
E) Ac causes a deletion next to the insertion site of Ds.

Question 7

Two formal terms used to describe categories of mutational nucleotide substitutions in DNA are _.

A) euchromatic and heterochromatic
B) transversions and transitions
C) sense and antisense
D) error prone and spontaneous
E) base analogs and frameshift

Question 8

Assume that a new mutation occurs in the germ line of an individual. What finding would suggest that the new mutation is dominant rather than recessive?

Question 9

Transposons, or jumping genes, are DNA elements that move within the genome. In which organismic groups are transposons found?

A) ancient bacteria
B) mammals
C) eukaryotes
D) bacteria
E) all organismic groups

Question 10

Ultraviolet light causes pyrimidine dimers to form in DNA. Some individuals are genetically incapable of repairing some dimers at "normal" rates. Such individuals are likely to suffer from
________.

A) Huntington Disease
B) muscular dystrophy
C) xeroderma pigmentosum
D) phenylketonuria
E) SCID

Question 11

Mutations that arise in nature, from no particular artificial agent, are called _.

A) oblique mutations
B) spontaneous mutations
C) cosmic mutations
D) induced mutations
E) chromosomal aberrations

Question 12

Conditional mutations are more likely to result from a mutation caused by which of the following alterations to the coding region of a gene?

A) four bases added within a short region of a gene
B) deletion
C) base addition
D) X rays
E) tautomeric shift

Question 13

How was it determined that X rays are mutagenic?

Question 14

Mutations may exert a variety of effects on living systems. List at least three categories of mutations based on their biological effects.

Question 15

Three major types of RNAs are mRNA, rRNA, and tRNA. For each of the conditions below, predict the consequences in terms of the population of proteins being
synthesized in a particular cell. What qualitative and quantitative changes, if any, are expected in the individual protein involved (if one is involved) and in the population of proteins produced in that cell?
a() A frameshift mutation in mRNA. The condition is heterozygous in the involved cell.
b() A deletion (homozygous) that removes approximately half of the rRNA genes.

Question 16

All insertion sequences (IS elements) contain two features that are essential for their movement. What are these two elements?

A) integrase and oncogenes
B) integrase and pseudogenes
C) proto -oncogenes and oncogenes
D) transposase and oncogenes
E) transposase and inverted terminal repeats

Question 17

Nutritional mutations can be described as _.

A) those mutations that do not allow a bacterium or fungus to grow on minimal medium but do allow growth on complete medium
B) all strains that are not auxotrophic
C) those mutations belonging to the group called prototrophs
D) those mutations caused by site -specific mutagenesis
E) those mutations that change the composition of the medium

Question 18

Under which condition(s) might one have an amino acid substitution in a protein that does not result in an altered phenotype?

Question 19

DNA may be damaged from the by -products of normal cellular aerobic respiration.
Name three of these electrophilic oxidants that are generally classified as reactive oxidants.

Question 20

Some bacterial transposons, known as Tn elements, are larger than insertion sequences (IS elements) and contain protein -coding genes that have human health significance. What might such a bacterial transposon contain?

A) pseudogene
B) oncogene
C) drug resistance
D) proto -oncogene
E) dissociation element

Question 21

Which human condition is caused by unrepaired UV -induced lesions?

Question 22

The process of error correction of mismatched bases carried out by DNA polymerases is called _.

Question 23

What is the Ames test, and how does it work?

Question 24

Some mutagens cause genetic changes that can be "corrected" by reexposing cells to the same mutagen. Other mutagens do not behave in this way. Provide one example of
each of these two types of agents and describe the mutational changes caused in DNA. Explain why some mutagens behave in one way, whereas others do not.

Question 25

Assuming one mutational event in a gene, on average, which of the following
mutagens or mutational conditions would be expected to cause the most damage to a protein synthesized by such a mutagenized gene: 5 -bromouracil, 2 -amino purine,
ethylmethane sulfonate, or frameshift?

Question 26

What is the common influence of ultraviolet light on DNA?

Question 27

Three human disorders-fragile -X syndrome, myotonic dystrophy, and Huntington disease-are conceptually linked by a common mode of molecular upset. Describe the phenomena that link these disorders.

Question 28

In a survey of 240,000 human births, 6 achondroplastic births were recorded to parents who were unaffected. Given that this form of dwarfism is caused by a fully penetrant, dominant, autosomal gene, what is the mutation rate?

Question 29

What is meant by the term photoreactivation repair?

Question 30

Under certain conditions, the rate of mutation of a particular gene may be fairly easy to determine. Name three properties of the mutation that would favor the most direct
determination of mutation rate.

Question 31

Considering the electromagnetic spectrum, identify likely mutagens from the following list: radio waves, microwaves, infrared, ultraviolet, X rays, gamma rays, cosmic rays.

Question 32

Describe the action of the enzyme transposase.

Question 33

Apurinic sites (AP sites) involve a spontaneous loss of a(n)________ in an intact double -helix DNA molecule.

Question 34

When X rays penetrate cells, electrons are ejected from atoms of molecules. Stable molecules can be transformed into which two types of hazardous materials?

Question 35

Describe the mutagenic action of the following two mutagens: 5 -bromouracil and ultraviolet light.

Question 36

Recent discoveries on causes of fragile -X syndrome, myotonic dystrophy, and Huntington Disease indicate which type of genetic alteration?

Question 37

Recombinational repair is activated when damaged DNA has escaped repair and the distortion disrupts the process of replication. Which gene is responsible for
recombinational repair?

Question 38

A mutation that occurs naturally, without exposure to a known mutagen, is called a(n)
________.

Question 39

How were insertion sequences (IS elements) first discovered?

Question 40

It has been found that a particular "+ -" combination of frameshift mutations in gene X gives a wild -type phenotype, whereas a "- +" combination gives a mutant phenotype, even though the sites of insertion/deletion are the same. How might these results be
explained?

Question 41

Although mutation is the original source of genetic variation, its influence on changing allelic frequencies is relatively minor.

Question 42

Strand discrimination during the process of DNA repair is based on DNA methylation in E. coli.

Question 43

Of the two cell lines that can contain a mutation in an organism, somatic line and germ line, the latter is more consequential to subsequent generations.

Question 44

When treating an organism with a mutagen, although it is possible that homozygous mutations will occur, it is more likely that most new mutations will be heterozygous or hemizygous.

Question 45

What are LINES?

Question 46

Certain base analogs such as 5 -bromouracil cause mutations by chemically altering nitrogenous bases in nonreplicating DNA.

Question 47

Pyrimidine dimers are typically caused by the mutagen 2 -amino purine.

Question 48

The shorter the wavelength of a radiation source, the greater its likelihood of causing damage.

Question 49

2 -amino purine is an alkylating agent.

Question 50

Loss -of -function mutations eliminate the function of a gene product and may be dominant or recessive.

Question 51

Postreplication repair is a system that responds after damaged DNA has escaped repair and failed to be completely replicated.

Question 52

IS elements (insertion sequences) are stable DNA occupants of prokaryotic genomes that are not found among eukaryotes.

Question 53

A missense mutation causes premature chain (protein) termination.