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