Deck 15: Gene Mutation,dna Repair,and Transposition

Question 1

Adenine methylase is an enzyme used during mismatch repair MMR).It helps determine which strand needs to be repaired by discriminating between template and new DNA strand.If this enzyme is mutated,how would MMR be affected?

A)MMR would not be hindered because adenine methylase is not directly involved in MMR.
B)MMR would be hindered because both strands would be unmethylated and both would appear as template DNA strands.
C)MMR would be hindered because both strands would be overmethylated and both would appear as template DNA strands and it would not be possible to determine which strand has the mutation.
D)MMR would be hindered because both strands would be unmethylated and both would appear as new DNA strands and it would not be able to determine which strand has the error.
E)MMR would be hindered because both strands would be overmethylated and both would appear as new DNA strands and it would not be able to determine which strand has the error.

Answer 1

D

Question 2

In bacteria and eukaryotes,a mutation is when__________ .

A)DNA is unable to be replicated
B)the expression of a gene changes without the DNA sequence being changed
C)the amino acid sequence in a protein molecule is directly changed
D)the nucleotide sequence in a DNA molecule is directly changed
E)the nucleotide sequence in an mRNA molecule is directly changed

Answer 2

the nucleotide sequence in a DNA molecule is directly changed

Question 3

Tautomeric shifts__________ .

A)are known to cause insertion or deletion mutations
B)can cause missense mutations due to mispairings
C)are likely to cause frameshifts
D)allow purines to bind to purines
E)allow pyrimidines to bind to pyrimidines

Answer 3

can cause missense mutations due to mispairings

Question 4

Thymine dimers form when __________.

A)two thymines are inserted into a DNA sequence
B)two thymines on separate strands of DNA bind to together
C)two thymines adjacent to each other are deleted from the DNA sequence
D)two thymines on the same strand and adjacent to each other bind together
E)two thymines on the same strand but not adjacent to each other bind together

Question 5

At what stage is a mutation predicted to have the effect?

A)shortly after birth
B)after birth but before puberty
C)after puberty
D)during early embryonic development
E)after the age of 60

Question 6

A geneticist is studying a particular Drosophila mutant that produces a phenotype of "no wing" due to a mutation in a gene called wingless.She takes the mutant wingless and mutagenizes it.She hypothesizes that any fly that emerges with wings will be due to the original mutated gene reverting back to the wild- type allele. From this study,she identifies a fly that now has wings.When she sequences the wingless gene,she discovers that the original mutation is still there,and there are no other mutations in the wingless gene.However,a second gene at a separate locus is mutated.The second mutation is best classified as an__________.

A)null mutation
B)intragenic suppressor mutation
C)conditional mutation
D)intergenic suppressor mutation
E)haploinsufficiency mutation

Question 7

Which f the following mutagens is matched correctly with its action?

A)2- Amino purine is an adduct- forming agent
B)acetaldehyde is a free radicle
C)5- Bromouracil is an alkylating agent
D)ethidium bromide is an intercalating agent
E)mustard gasses are base analogs

Question 8

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

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

Question 9

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

Question 10

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

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

Question 11

Which of the following mutations would be classified as a transversion?

A)CGA to a CGU
B)CGA to a GGA
C)CGA to a CCA
D)CGA to GCT
E)CGA to a CGT

Question 12

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

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

Question 13

Which repair mechanism is most likely affected if the enzyme DNA glycosylase is not functioning properly?

A)base excision repair
B)photoreactivation repair
C)SOS repair
D)double- strand break repair
E)nucleotide excision repair

Question 14

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

A)induced mutations
B)spontaneous mutations
C)nutritional mutations
D)chromosomal losses
E)cosmic mutations

Question 15

A mutation that changes an amino acid- coding codon to a stop codon is classified as what kind of codon?

A)missense
B)nonsense
C)neutral
D)conditional
E)silent

Question 16

Germ cell mutations__________ .

A)are of no consequence to the next generation
B)are only seen in females
C)are the cause of testicular cancer
D)are usually found in every cell of the next generation
E)affect somatic cell function in the current generation

Question 17

Which of the following diseases are caused by an expansion of trinucleotide repeats?

A)achondroplasia
B)cystic fibrosis
C)beta- thalassemia
D)fragile X syndrome
E)Marfan's syndrome

Question 18

From the Luria- Delbruck fluctuation test,when would mutations arise in yeast cells to allow for survival in the presence of toxic levels of hydrogen peroxide?

A)Mutations are adaptive and would have formed prior to being exposed to hydrogen peroxide.
B)Mutations are adaptive and would have appeared immediately in response to the hydrogen peroxide.
C)Mutations are random and would have appeared prior to being exposed to hydrogen peroxide.
D)Mutations are random but would not have formed until after the hydrogen peroxide was introduced.
E)Mutations are adaptive and would have appeared after most of the cells died in the presence of hydrogen peroxide.

Question 19

One would predict that bacteria that lack the enzyme photolyase would be more sensitive to what kind of mutagen?

A)base analog
B)alkylating agents
C)intercalating agents
D)UV light
E)reactive oxygen species

Question 20

During the Ames test,his- bacteria are exposed to a chemical.If the bacteria remains his+,then what can we say about the chemical?

A)The chemical is certainly a cancer- causing chemical.
B)The chemical is not safe to consume because it is likely a mutagen.
C)The chemical is not safe to consume even though it is not likely a mutagen.
D)The chemical is safe to consume even though it is likely a mutagen.
E)The chemical is safe to consume and is not likely a mutagen.

Question 21

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

Question 22

Barbara McClintock discovered mobile elements in corn by analyzing the genetic behavior of two elements,Ds and Ac.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)The movement of Ac is dependent on two forms of Ds.
B)Both elements can move only within chromosome 9.
C)Ac causes a deletion next to the insertion site of Ds.
D)While Ds moves only if Ac is present in the genome,Ac is capable of autonomous movement.
E)Ds causes a deletion next to the insertion site of Ac.

Question 23

Explain the effects of a somatic mutation on the individuals and their offspring if the mutation is recessive or dominant.

Question 24

Describe the action of the enzyme transposase.

Question 25

In World War I,mustard gas was used as a chemical weapon,and at a high dose,it would cause death. However,it is now known to be a chemical mutagen.Explain how those who came in contact with mustard gas and survived have an increase chance of developing mutations.

Question 26

What are LINES?

Question 27

How were insertion sequences IS elements)first discovered?

Question 28

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 29

Compare and contrast between the following types of mutations: missense,nonsense,silent,and neutral.

Question 30

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

Question 31

Three major types of RNAs are mRNA,rRNA,and tRNA.For each of the conditions below,predict the conseque terms of the population of proteins being synthesized in a particular cell.What qualitative and quantitative chan any,are expected in the individual protein involved if one is involved)and in the population of proteins produc 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 32

How was it determined that X- rays are mutagenic?

Question 33

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 34

A heterozygote could have a variety of phenotypes depending on whether or not the mutation is recessive,dominant,or haploinsufficient.In this example,the gene A is necessary to form a tail in mice.If the mouse is a heterozygote A/a),then what would you predict the phenotype to be if the mutation was recessive,dominant,or haploinsufficient.

Question 35

What is meant by the term photoreactivation repair?

Question 36

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 37

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

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

Question 38

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

Question 39

In a survey of 240,000 human births,six 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 40

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