BIO311: Ch. 19 Gene Mutation and DNA Repair

Which of the following are base analogs?

- 2-aminopurine - 5-bromouracil

Which of these are examples of mutagens?

- 5-Bromouracil - Nitrous acid - Nitrogen mustard - 2-Aminopurine

Which of the following are examples of base pair mismatches?

- Cytosine on parent strand and Thymine on daughter strand - Adenine on parent strand and Cytosine on daughter strand - Cytosine on parent strand and Adenine on daughter strand

Which of the following terms is associated with ionizing energy?

- Gamma rays - Short wavelength - High energy

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

10-2 ; higher

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

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

How does ionizing radiation cause mutations?

It forms free radicals that can introduce breaks into the DNA molecule.

A heritable change in the genetic material is called a(n) ______.

Mutation

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

The Ames test

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

True

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

abnormal bases

Replica plating is a technique in which ______.

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

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

Base analogs induce mutations by ______.

being incorporated instead of normal bases during DNA replication

Physical mutagens include ______.

both X-rays and UV light

Nitrous acid is a mutagen that acts via the process of ______.

deamination

The removal of an amino group from a base is called _________.

deamination

This figure highlights the process of ______.

deamination

Acridine dyes cause ______ mutations.

frameshift

Ionizing radiation produces chemically reactive molecules known as _______ . These are mutagenic because they alter the structure of DNA.

free ; radicals

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

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

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

methyl ; ethyl

The term _____ refers to an inherited change in the sequence of the genetic material.

mutation

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

mutation ; rate

Changes to DNA structure caused by reactive oxygen species (ROS) are termed ________ _______ __________ .

oxidative ; DNA ; damage

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

A breakpoint refers to the region ______.

where two chromosome pieces break and rejoin with other chromosome pieces

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

- Homologous recombination repair - Nonhomologous end joining

Which of these are examples of alkylating agents?

- Nitrogen mustard - Ethyl methanesulfonate

Which of the following statements about promoter mutations is true?

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

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

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

breakpoint

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

bulky, helix distorting lesions

A silent mutation is a mutation that results in no ______.

change to the amino acid sequence of the polypeptide

The removal of a purine from DNA is called ______

depurination

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

depurinations

Alkylating agents cause mutations by ______.

disrupting the normal pairing between nucleotides within the DNA

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

mutagen

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

photoreactivation

This figure shows a technique known as __________ .

replica ; plating

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

spontaneous ; induced

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

substitution

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

trinucleotide ; repeat ; expansion

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

less ; less

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

reactive oxygen species

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

germ ; line

Acridine dyes induce mutations by ______.

inserting themselves between adjacent bases and thus distorting DNA structure