BIOL 3721 Chapter 19

Which of the following are examples of base pair mismatches?

Cytosine on parent strand and adenine on daughter strand Adenine on parent strand and cytosine on daughter strand Cytosine on parent strand and thymine on daughter strand

Replica plating is a technique in which

bacterial colonies are transferred from one plate to another with a sterile piece of velvet cloth

Nucleotide excision repair (NER) is the main system used in the repair of

bulky, helix-distorting lesions

Some errors create bulky distortions of the double helix. These errors are removed primarily by a DNA repair system called NER, which stands for ___ ___ repair.

nucleotide excision

The phenomenon in which a repeated sequence of three nucleotide bases increases in number generation after generation is called

trinucleotide repeat expansion

Which of the following are base analogs?

2-aminopurine and 5-bromouracil

Which of these are examples of mutagens?

5-Bromouracil 2-Aminopurine Nitrogen mustard Nitrous acid

This figure best illustrates what type of mutation?

Base Substitution

Which of these represents the correct order of steps during a typical DNA repair system?

Detection → Removal → Replication

Which of the following statements about promoter mutations is true?

Down promoter mutations decrease the affinity of transcription factors to the promoter. Up promoter mutations cause the promoter sequence to be more like the consensus sequence.

Double-strand breaks are typically repaired by which of the following?

Homologous recombination repair Nonhomologous end joining

In this figure, two panels are shown. Panel I shows protein A. A first mutation inhibits the function of protein A. In Panel II a second mutation alters protein B to carry out the function of protein A. What is this an example of?

Intergenic suppression

Base excision repair (BER) is the main system used in the repair of

abnormal bases

A mutagen is a(n)

agent that causes mutations

A silent mutation is a mutation that results in no

change to the amino acid sequence of the polypeptide

Nitrous acid is a mutagen that acts via the process of Blank

deamination

The removal of a purine base from DNA is called

depurination

The two main mechanisms used to repair DNA double-strand breaks are ___ recombination repair and ___ end joining.

homologous; nonhomologous

Trinucleotide repeat expansions are repeated sequences of three nucleotide bases which

increase in number generation after generation

Acridine dyes induce mutations by

inserting themselves between adjacent bases and thus distorting DNA structure

Changes in DNA structure caused by reactive oxygen species (ROS) are collectively called ___ DNA ___.

oxidative; damage

The process by which thymine dimers are directly repaired with the help of light is called

photoreactivation

Oxidative DNA damage refers to changes in DNA structure that are caused by

reactive oxygen species

A change of one base for another is described as a base ___ mutation.

substitution

Translesion DNA polymerases incorporate wrong nucleotides with a frequency of approximately ______, which is ______ than the error rate for replicative DNA polymerases.

10-2 ; higher

Certain compounds have a structure similar to normal DNA bases and so can be incorporated into daughter strands during DNA replication. These compounds are called base

analogs

Base analogs induce mutations by

being incorporated instead of normal bases during DNA replication

Physical mutagens include

both X-rays and UV light

The region where two chromosome pieces break and re-attach to other chromosome pieces is called a chromosomal

breakpoint

The term germ line is used to describe the

cells that produce sperm and eggs

Mutations that remove an adenine or guanine from the DNA are known as

depurinations

An allele that has a DNA sequence different from that of the wild-type is called a(n) ___ allele.

mutant

A heritable change in the sequence of the genetic material is called a(n)

mutation

A breakpoint refers to the

region where two chromosome pieces break and rejoin with other chromosome pieces

Mutations can be caused in two main ways: (1) ___ mutations are the result of natural biological or chemical processes; and (2) ___ mutations are produced by environmental agents.

spontaneous; induced

Most DNA repair systems involve three major steps: detection of the error, removal of the abnormality, and its replacement with normal DNA.

true

Mutations that occur in a promoter sequence can be divided into two types: ___ promoter mutations increase the transcription rate, while ___ promoter mutations decrease it.

up; down

The mutagen nitrous acid changes cytosine to ___ and adenine to ___.

uracil; hypoxanthine

Which of these tests is used to evaluate the mutagenicity of an agent?

The Ames test

A permanent change in the genetic material that can be passed from mother to daughter cells during cell division is referred to as a(n)

mutation

The probability that a gene will be altered by a new mutation is referred to as the

mutation rate

Cells that give rise to the gametes such as eggs and sperm are called

germ cell

A mutant allele is best defined as an allele that

has a different DNA sequence from the wild-type

This figure shows an example of a(n) ___ ___ mutation.

intragenic suppressor

Some errors affect individual nucleotides and do not distort the DNA double helix. These errors are removed primarily by a DNA repair system called BER, which stands for ___ ___ repair.

base excision

During the normal course of DNA replication, the addition of a nucleotide that does not obey the AT/GC rule of base pairing creates a

base pair mismatch

Photoreactivation is a repair mechanism that can ______ a thymine dimer in the ______ of light.

directly split; presence

Alkylating agents cause mutations by

disrupting the normal pairing between nucleotides within the DNA

Acridine dyes cause ______ mutations.

frameshift

The Ames test assays whether an agent causes

gene mutations

The mutation rate is commonly expressed as the number of new mutations in a given

gene per cell generation

Translesion DNA polymerases are ______ accurate and ______ sensitive to geometric distortions in DNA than replicative DNA polymerases.

less; less

Alkylating agents covalently attach ___ or ___ groups to DNA bases, and thus disrupt their normal base pairing properties.

methyl; ethyl

Alkylating agents include nitrogen ___ and ethyl ___ .

mustard; methanesulfonate

An agent that can change DNA structure and cause mutations is known as a(n)

mutagen

Which of these are examples of alkylating agents?

nitrogen mustard and ethyl methanesulfonate

This figure shows a technique known as

replica plating

A mutation that does not change the amino acid sequence of a polypeptide is known as a(n) ___ mutation.

silent

Errors in DNA replication are examples of ______ mutations, while mutations caused by ultraviolet light are ______ mutations.

spontaneous; induced