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