BIO CH.19

Which of the following are base analogs?

5 2

Which of these are examples of mutagens?

5-Bromouracil 2-Aminopurine Nitrogen mustard Nitrous acid

In this figure, the normal DNA coding sequence of a gene is shown on top, along with four different mutations. Match the mutation to its appropriate description. A B C D

A Silent mutation B Missense mutation C Nonsense mutation D Frameshift mutation

Which changes can cause a frameshift mutation?

A base deletion A base addition

Which are examples of somatic mutations?

A mutation in an adult muscle cell A mutation in an embryonic kidney cell

Assume a tautomeric shift occurred, which was followed by two rounds of DNA replication. If the mutation is not repaired, what would be the result?

AT to GC mutation in one of the four daughter molecules

Which of the following are forms of tautomers?

Amino Imino Keto Enol

Genetic anticipation refers to what phenomenon?

An increase in severity of the symptoms as a disease is passed through future generations

This figure best illustrates what type of mutation?

Base substitution

In trinucleotide repeat expansion disorders, when the expansion occurs in the coding sequence of the gene, the repeat sequence is usually ______.

CAG

Which of the following statements about nonionizing radiation are true?

Contains low energy Includes ultraviolet light

Which of these bases is most readily deaminated?

Cytosine

Which of these are examples of alkylating agents?

Ethyl methanesulfonate Nitrogen mustard

True or false: Deleterious mutations that cause the death of a cell are called nonsense mutations.

False

Which of the following terms is associated with ionizing energy?

Gamma rays High energy Short wavelength

Which of these are trinucleotide repeat expansion disorders?

Huntington disease Fragile X syndrome Myotonic muscular dystrophy

Which of these point mutations would likely have an inhibitory effect on protein function?

Nonsense Missense Frameshift

What type of mutations involve a change from a normal codon to a stop codon?

Nonsense mutations

Which term refers to the imbalance between an organism's abilities to produce reactive oxygen species (ROS) and to break them down?

Oxidative stress

Which of these mutations changes a mutant allele back to a wild-type allele?

Reversion

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

Which of the following are examples of ionizing radiation?

X-rays and gamma rays

Some trinucleotide repeat disorders get progressively more severe in future generations. This phenomenon is termed ____.

anticipation

The covalent bond between deoxyribose and a purine base is rather unstable and can undergo a spontaneous reaction with water. The breaking of the bond releases the base, and leaves a(n) ____ site in the DNA.

apurinic

The red arrow in this figure points to a(n) _____ _____.

apurinic site

Replica plating is a technique in which ______.

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

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

Nitrous acid changes the base adenine to hypoxanthine, which pairs with the base ___. This leads to mutations in the newly-synthesized DNA strand during DNA replication.

cytosine

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

For a tautomeric shift to cause a mutation, it must occur ______.

immediately prior to DNA replication

Trinucleotide repeat expansions are repeated sequences of three nucleotide bases which ______.

increase generation after generation

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

intragenic suppressor

Gamma rays and X-rays are examples of a type of radiation called ____radiation.

ionizing

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

methyl ethyl

A base substitution in DNA that ultimately leads to a change in the encoded amino acid is called a(n) _____ mutation.

missense

A mutation in a gene that causes an amino acid change in the encoded protein is called a ______ mutation.

missense

Nitrous acid causes mutations by ______.

modifying bases and thus altering their normal base-pairing properties

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

mutation

A mutation that results in a premature termination of the synthesis of a polypeptide is called a(n) _____ mutation.

nonsense

Changes to DNA structure caused by reactive oxygen species (ROS) are termed ___ ___ ___.

oxidative DNA damage

An imbalance between the production of reactive oxygen species and an organism's ability to break them down is known as ___ ___.

oxidative stress

Reactive oxygen species (ROS) are ______.

products of oxygen metabolism in all aerobic organisms

Acridine dyes are planar molecules that include ______.

proflavin

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

reactive oxygen species

This figure shows a technique known as ___ ____.

replica plating

A chemical agent is being assayed for mutagenicity using the Ames test. This agent would be judged to be a mutagen if the number of bacterial colonies on the test plate is ______.

significantly higher than that of the control plate

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

silent

Mutations in body cells that do not go on to form gametes are known as ______ mutations.

somatic

The patch of white hair in this child is most likely caused by a ______ mutation.

somatic

If the patch of white hair in this child were larger, that would indicate a ______ mutation that occurred ______ during embryonic development.

somatic; earlier

A second mutation that occurs in a different site than the first mutation, and which converts the mutant back to the wild-type phenotype, is best referred to as a(n) ____ mutation.

suppressor

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

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 base cytosine is deaminated to produce the base ____.

uracil

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

In a natural population, a ___ ___ genotype is the most common one.

wild type

What is the effect of a suppressor mutation?

It suppresses the phenotypic effect of another mutation.

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

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

spontaneous ; induced

Base analogs include 2- ___ and 5-___.

aminopurine bromouracil

A mutagen is a(n) ______.

an agent that causes mutation

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 ___.

analog

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

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

substitution

Ultraviolet light causes the formation of crosslinked ___ ___ in DNA.

thymine dimers

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

trinucleotide repeat expansion

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

mutation

The wild type genotype or phenotype is the one that is ______ found in nature.

typically

Proteins associated with trinucleotide repeat expansion disorders typically contain long tracts of the amino acid ___.

glutamine

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

mutagens

Examples of trinucleotide repeat expansion (TRNE) disorders include ___ muscular dystrophy and ___X syndrome.

bulbar fragile

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

Alkylating agents cause mutations by ______.

disrupting the normal pairing between nucleotides within the DNA

Nonionizing radiation is characterized by ______.

long wavelength and low energy

Alkylating agents include nitrogen ____ and ethyl ___.

mustard methanesulfonate

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

mutant

Acridine dyes induce mutations by ______.

inserting themselves between adjacent bases and thus distorting DNA structure

The addition or deletion of a number of bases that is not a multiple of 3 causes a(n) _____ mutation.

frameshift

How does ionizing radiation cause mutations?

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

A temporary change in base structure due to movement of hydrogen atoms is called a(n) ___ ___.

tautomeric shift

Proflavin is best described as a(n) ______ agent.

intercalating

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

A ___ mutation is one that converts a mutant allele back to the wild-type form.

reversion

A mutation that results in the death of an organism is known as a(n) ____ mutation.

lethal

Ionizing radiation is characterized by ______.

short wavelength and high energy

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

germ line

Products of oxygen metabolism, such as hydrogen peroxide, superoxide, and hydroxyl radical, are collectively called ___ ___ species.

reactive oxygen