Chapter 19

Which of the following base changes is a transition mutation? A. A to G B. A to T C. C to A D. A to C E. C to G

A to G

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

The Ames test

Oxidative DNA damage refers to changes in DNA structure that are caused by ____________________. A. tautomeric shifts B. Non-ionizing radiation C. alkylating agents D. reactive oxygen species

D. reactive oxygen species

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

Deanimation

Silent mutations are possible because the genetic code it _________. A. biased B. Non-overlapping C. Universal D. Degenerate

degenerate

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

frameshift

A mutant allele is best defined as an allele that ____________________. a. Has a different DNA sequence from wild-type B. can no longer be transcribed into mRNA C. encodes a protein that causes a disease.

A. has a different DNA sequence form wild-type

The Ames test assays whether an agent causes _____________________.

gene mutations

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

germ-line

The Ames test uses a strain of the bacterium Salmonella typhimurium that is unable to produce the amino acid ___________________.

histidine

Nitrous acid causes mutations by _____________________. A. creating thymine dimers that block DNA replication B. acting as a base analog during DNA replication C. modifying bases and thus altering their normal base-pairing properties D. forming free radicals that damage DNA structure.

C. modifying bases and thus altering their normal base-pairing properties.

The wild type genotype of phenotype is the one that is ___________________ found in nature. A. always B. rarely C. typically D. never

C. typically

Bacterial possess ______________ DNA repair systems.

several different

A ________________ is a type if base substitution that involves a change of a pyrimidine to another pyrimidine, or a purine to another purine.

transition

Thymine dimers are typically caused by?

ultraviolet light

An allele that has a DNA sequence different from that of the wild-type is called a ___________________ allele.

Mutant

Which of the following are examples of ionizing radiaton?

x-rays and gamma rays

Mutation

A heritable change in the genetic material is called a _________.

Which are examples of somatic mutations? A. a mutation in an adult muscle cell B. a mutation in a sperm cell C. a mutation in an egg cell D. a mutation in an embryonic kidney cell.

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

The DNA sequence of the coding stranding of a gene is depicted in the figure. Below it are four different types of mutations. Which of them are transverse mutations? A B C D

A,B,C

In a neutral mutation, a negatively-charged amino acid is substituted for ______________________. A. another negatively- charged amino acid B. a positively-charges amino acid C. an uncharged amino acid

A. another negatively-charged amino acid

Reactive Oxygen Species (ROS) are A. organisms that have adverse reactions when grown in oxygen B. products of oxygen metabolism in all aerobic organisms C. organisms that can only grow in the presence of oxygen D. products of metabolism in the absence of oxygen

B. products of oxygen metabolism in all aerobic organisms.

Which changes can cause a frameshift mutation? A. A base transversion B. A base transition C. A base addition D. A base deletion

Base addition and deletion

Mutations in body cells that do not go on to form gametes are known as _______________ mutations. A. somatic B. conditional C. auxotrophic D. germ-line

Somatic

Which is the following bases changes are transversion mutations?

G to C A to T A to C

What is associated with ionizing energy?

Gamma rays, high energy, short wavelength

In which of the following ways does 5-bromouracil cause a mutation?

It replaced the base thymine, and can base pair with guanine rather than adenine.

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

Missense

Why is rat liver extract used in the Ames test for mutagenicity?

Rat liver contains enzymes that can activate the mutagen

In the Ames test for mutagenicity, the control sample contains what?

Rat liver extract + Salmonella bacteria that cannot synthesize histidine.

What bacterium is used in the Ames test?

Salmonella typhimurium

Ionizing radiation is characterized by ______________.

Short wavelength and high energy

A mutation that does not change the amnio acid sequence of a polypeptide in known as a(n) _____________________ mutation.

Silent

A- Silent Mutations B- Missense mutations C- Non-sense mutations D. frameshift mutations

Silent Mutations Missense Mutations Non-sense Mutations Frameshift Mutations

What is responsible for silent mutations? A. frameshift mutations B. the degeneracy of the genetic code C. The DNA repair systems in a cell D. Reverse mutations

The degeneracy of the genetic code

You are using the Ames test to assay the mutageicity of a compound. However you forgot to add the rat liver extract. What can you say about the results?

The results will be less relevant to mammals.

The mutagen nitrous acid changes cytosine to _______________ and adenine to ______________________.

Uracil; hypoxanthine

5-bromouracil is a base ______________ that changes a _________________.

analog; AT base pair to a GC base pair

A mutagen is _____. A. organism that has undergone a mutation B. agent that causes mutations C. protein that repairs mutated DNA

b. agent that causes mutations

Physical mutagens include ________________. A. x-rays but not UV light B. UV light but not X-rays C. neither X-rays nor UV light D. both X-rays and UV light

both x-rays and UV light

Nucleotide Excision Repair (NER) is the main system used in the repair of __________________.

bulky, helix distorting lesions

The term germ line is used to describe the ________________________. A. region where cells form the cleavage furrow during mitosis B. cells that produce sperm and eggs C. cells that defend again microbes D. area where chromosomes line up during cell division

cells that produce sperm and eggs.

A silent mutation is a mutation that results in no ______________________. A. change in the nucleotide sequence of the DNA B. expression of the protein encoded by the gene C. change to the nucleotide sequence of the messenger RNA D. change to the amino acid sequence of the polypeptide

change to the amino acid sequence of the polypeptide.

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

cytosine

Which of the following statements about ionizing radiation are true?

includes ultralviolet light and contains low energy

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

ionizing

nonionizing radiation is characterized by __________________.

long wavelength and low energy

During DNA replication, a base that does not obey the normal AT/GC base pairing rule is added. This type of mutation is most likely corrected by the ________________ repair system.

mismatch

If the proofreading ability of DNA polymerase fails, which of the following DNA repair systems is most likely to detect the resulting mutation and fix them?

mismatch repair system

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

missense

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

mutagens

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

mutations

Bacterial strains that lock one or more DNA repair systems have a very high mutation rate. These are called ______________ strains.

mutator

A(n) ____________________ mutation is a missense mutation that has no detectable effect on protein function.

neutral

Which of these are examples of mutagens? A. adenosine triphosphate B. cytosine C. 2-aminopurine D. 5-Bromouracil E. Guanine F. Nitrogen mustard G. Nitrous acid

nitrous acid nitrogen mustard 5-bromouracil 2-aminopurine

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

nonsense

What type of mutations involve a change from a normal codon to a stop codon? A. missense mutation B. Inversion mutation C. Frameshift mutation D. Nonsense mutation

nonsense mutation

Changes to DNA structure by reactive oxygen species (ROS) are termed __________________ __________________ _________________________.

oxidative DNA damage

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

oxidative DNA damage

A ________ mutation refers to a mutation in which just one base is changed within the DNA sequence. A. point B. Core C. locus D. allele

point

A change in a single base pair in the genetic material is known as a _________________.

point

A change in a single base pair in the genetic material is known as a(n) _______________________ mutation.

point

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

reactive oxygen

Bacteria posses _____________ DNA repair system. A. only a single B. Several Different C. No

several different

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

significantly high than that of the control plate.

base substitution mutation

simple substitution of one base for another

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

A(n) __________________________ is a type of base substitution that involves a change of a pyrimidine to another pyrimidine, or a purine to another purine.

transition

A base substitution in which purine and pyrimidine are interchanged is called a _____________________ mutation.

transversion

In a natural population, a ______________-________________ genotype is the most common one.

wild-type