Genetics Exam 4 Review #2

Which of the following are examples of ionizing radiation?

- X-rays - gamma rays

Which of these are examples of mutagens?

- 2-aminopurine - nitrous acid - nitrogen mustard - 5-bromouracil

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.

Examples of base pair mismatches are ______ on the parent strand with ______ on the daughter strand. Multiple select question.

- adenine, cytosine - cytosine; thymine - cytosine; adenine

Which of these are examples of alkylating agents?

- ethyl methanesulfonate - nitrogen mustard

Which of these are disorders that involve trinucleotide repeat expansion?

- fragile X syndromes - Huntington disease - myotonic muscular dystrophy

Physical mutagens include ______.

both X-rays and UV light

A mutagen is a(n) ______.

agent that causes mutations

Base analogs include 2-_____ and 5-_____.

aminopurine; bromouracil

Genetic anticipation refers to which phenomenon?

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

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

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

anticipation

The arrow in this figure points to a(n) ______ site.

apurinic

Nucleotide excision repair (NER) is found in ______.

both prokaryotes and eukaryotes

Which of the following statements about nonionizing radiation are true?

- has low energy - includes ultraviolet light

Which of the following are forms of tautomers?

- imino - amino - enol - keto

What can cause double-strand breaks (DSBs)?

- reactive oxygen species - gamma rays - X-rays

Which of the following terms is associated with ionizing energy?

- short wavelength - gamma rays - high energy

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

deamination

The mutagen nitrous acid changes cytosine to uracil, and adenine to hypoxanthine, through the process of

deamination

The removal of an amino group from a base is called

deamination

This figure highlights the process of ______.

deamination

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

ionizing

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

lethal

Nonionizing radiation has ______ wavelength and thus ______ energy.

long, low

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

methyl; ethyl

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

Which type of mutation involves a change from a normal codon to a stop codon?

nonsense mutation

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

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

oxidative stress

Which term refers to the imbalance between an organism's production of ROS and the ability to break them down?

oxidative stress

A suppressor mutation is so named because it suppresses the ______.

phenotypic effect of another mutation

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

photoreactivation

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

point

A(n) ______ mutation refers to a mutation in which just one base is changed within the DNA sequence.

point

Reactive oxygen species (ROS) are ______.

products of oxygen metabolism in all aerobic organisms

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

reactive oxygen

This figure shows a technique known as

replica plating

Ionizing radiation is characterized by ______.

short wavelength and high energy

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

silent

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

the Amers test

How does ionizing radiation cause mutations?

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

Acridine dyes cause ______ mutations.

frameshift

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

germ cells

A mutation that occurs directly in a sperm or egg cell, or in one of their precursor cells, is referred to as a(n) _____ - _____ mutation.

germ line

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

increase in number from generation to generation

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

missense

Cells of the body other than germ-line cells are called ______ cells.

somatic

Muscle cells, nerve cells, and skin cells are examples of ______ cells.

somatic

Which of the following are base analogs?

5-bromouracil 2-aminopurine

The region where two chromosome pieces break apart and reattach to other chromosome pieces is called a chromosomal

breakpoint

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

depurinations

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

Deleterious mutations that cause the death of a cell are called nonsense mutations.

False called lethal mutations

A mutation that involves the removal of a purine from DNA is called

depurination

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

mutation

A germ-line mutation is one that occurs in ______.

sperm or egg cell

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

trinucleotide repeat expansion

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

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

Replica plating is a technique in which ______.

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

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

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 ______.

cells that produce sperm and eggs

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

detection → removal → replication

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

The breakage of chromosomes is referred to as a(n) _____-_____ break.

double strand

The nucleotide excision repair system of DNA repair is unique to prokaryotes.

false

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

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

The mutation rate is commonly expressed as the number of new mutations ______.

in a given gene per cell generation

Intercalating agents like acridine dyes induce mutations by ______.

inserting themselves between adjacent bases and thus distorting DNA structure

If the proofreading ability of a DNA polymerase fails, which of the following DNA repair systems is most likely to detect the resulting mutations 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

Alkylating agents include nitrogen _____ gas and ethyl _____ (EMS).

mustard; methanesulfonate

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

mutagen

Fill in the blank question. An allele that has a DNA sequence different from that of the wild type is called a(n) _____ allele.

mutant

An inherited change in the sequence of the genetic material is called a(n)

mutation

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

mutation rate

Examples of trinucleotide repeat expansion (TRNE) disorders include _____ muscular dystrophy and _____ X syndromes.

myotonic; fragile

A silent mutation is a mutation that results in ______.

no change to the amino acid sequence of the polypeptide

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

nonsense mutation

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

spontaneous; induced

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

Base analogs induce mutations by ______.

substituting for normal bases during DNA replication

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

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

thymine dimers

The synthesis of DNA over a template strand that harbors some type of DNA damage is called _____ synthesis.

translesion

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

true

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

typically

Thymine dimers are typically caused by ______.

ultraviolet light

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

A breakpoint refers to the region ______.

where two chromosome pieces break and rejoin with other chromosome pieces

In a natural population, the most common genotype is the _____-_____ genotype.

wild type