exam 4
A mutation that is a base analog is
5-bromouracil
Assume a tautomeric shift occurred for a thymine base, and was followed by two rounds of DNA replication. If the mutation is not repaired, the result would be a(n) ______ to ______ mutation in ______ of the four daughter molecules.
AT; GC; one
In trinucleotide repeat expansion disorders, when the expansion occurs in the coding sequence of the gene, the repeat sequence is usually ______.
CAG (glutamine)
How does ionizing radiation cause mutations?
It forms free radicals that can introduce breaks into the DNA molecule.
Which of these are used by cells to limit the harmful effects of reactive oxygen species?
catalase Vitamin C superoxide dismutase
Nitrous acid changes the base adenine to hypoxanthine, which pairs with the base
cytosine
Which of these bases is most readily deaminated?
cytosine
Nitrous acid replaces amino groups with keto groups, a process called
deamination
The removal of an amino group from a base is called
deamination
A mutation that involves the removal of a purine from DNA is called
depurination
A point mutation could be caused by
depurination, deamination, tautomeric shift
In the nucleotide excision repair in E. coli, the function of the UvrA/UvrB complex is to
detect DNA damage
Cells can prevent the buildup of reactive oxygen species by using enzymes such as catalase and superoxide ____
dismutase
Alkylating agents cause mutations by ______.
disrupting the normal pairing between nucleotides within the DNA
Acridine dyes cause ______ mutations.
frameshift
Double-stranded breaks can be repaired by
homologous recombination repair (HRR) or nonhomologous end joining (NHEJ)
Trinucleotide repeat expansions are repeated sequences of three bases which ______.
increase in number from generation to generation
A mutation in one gene that reverses the effects of a mutation in a different gene is
intergenic suppressor
Which of the following are forms of tautomers?
keto amino enol imino
A down promoter mutation causes the promotor of a gene to be _____ like the consensus sequence and ____ transcription
less, inhibits
Nitrous acid causes mutations by ______.
modifying bases and thus altering their normal base-pairing properties
Alkylating agents include nitrogen ____ gas and ethyl ________
mustard, methanesulfonate
The formation of a hairpin during DNA replication can lead to an increase in the length of a DNA region if it occurs in ______.
newly made daughter cell
A mutation changes a codon that specifies tyrosine into a stop codon. This type of mutation is a
nonsense mutation
Which of the following DNA repair systems may involve the removal of a segment of a DNA strand?
nucleotide excision repair, mismatch repair
An advantage of translesion-replicating polymerases is that they can replicate ____, but a disadvantage is that they ____
over damaged DNA, have low fidelity
Which term refers to the imbalance between an organism's production of ROS and the ability to break them down?
oxidative stress
Reactive oxygen species (ROS) are ______.
products of oxygen metabolism in all aerobic organisms
Acridine dyes are planar molecules that include ______.
proflavin
Products of oxygen metabolism, such as hydrogen peroxide, superoxide, and hydroxyl radical, are collectively called
reactive oxygen
Oxidative DNA damage refers to changes in DNA structure that are caused by ______.
reactive oxygen species
In an Ames test, a ____ number of colonies is observed if a substance ____ a mutagen, compared with the number of colonies for a control sample that is not exposed to the suspected mutagen
significantly higher, is
A temporary change in base structure due to movement of hydrogen atoms is called a(n)
tautomeric shift
Bases which exist in keto and enol or amino and imino forms are best described as ______.
tautomers
A tautomeric shift is a ______.
temporary change in base structure
In the replica plating experiments of the Lederbergs, bacterial colonies appeared at the same locations on each of two secondary plates because
the mutations occurred on the master plate prior to T1 exposure and prior to replica plating
The function of photolyase is to repair
thymine dimers
The phenomenon in which a repeated sequence of three bases increases in number generation after generation is called
trinucleotide repeat expansion
The base cytosine is deaminated to produce the base
uracil
Physical mutagens include ______.
x-rays and uv light
One way that TNRE may occur involves the formation of ____ that disrupts ____
a hairpin, DNA replication
Which of the following is NOT an example of a spontaneous mutation?
a mutation caused by UV light
Which of the following is an example of a somatic mutation?
a mutation in an embryonic muscle cell, a mutation in a sperm cell
Base analogs include 2-____ and 5-____
aminopurine; bromouracil
Some trinucleotide repeat disorders get progressively more severe in future generations. This phenomenon is termed
anticipation
Nitrous acid is a mutagen that acts via the process of ______.
deamination
