Genetics Reading 13
Translesion DNA polymerases incorporate wrong nucleotides with a frequency of approximately _____, which is ______ than the error rate for replicative DNA polymerases.
10-2 ; higher
In recombination, what is the process that synthesizes small stretches of DNA to replace those removed by strand degradation?
DNA gap repair synthesis
Which of these represents the correct order of steps during a typical DNA repair system?
Detection → Removal → Replication
Which of the following statements about promoter mutations is true?
Down promoter mutations decrease the affinity of transcription factors to the promoter Up promoter mutations cause the promoter sequence to be more like the consensus sequence
Which of these are examples of mutagens?
Nitrous acid 5-Bromouracil Nitrogen mustard 2-Aminopurine
Double-strand breaks are typically repaired by which of the following?
Nonhomologous end joining Homologous recombination repair
Homologous recombination is a process in which
a new combination of DNA sequences is formed through breakage and rejoining of similar or identical DNA segments.
Base excision repair (BER) is the main system used in the repair of
abnormal bases
Which of these tests is used to evaluate the mutagenicity of an agent?
ames test
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 mutation
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
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
A silent mutation is a mutation that results in no
change to the amino acid sequence of the polypeptide
The first proposal for a set of steps at the molecular level that lead to homologous recombination is called the __ model.
holliday
Trinucleotide repeat expansions are repeated sequences of three nucleotide bases which
increase generation after generation
An allele that has a DNA sequence different from that of the wild-type is called a(n) __ allele.
mutant
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, escision
Changes to DNA structure caused by reactive oxygen species (ROS) are termed
oxidative DNA damage
In addition to the DNA strands of the chromosomes involved in homologous recombination, the multiple steps in the pathway require the action of
protein catalyst
Oxidative DNA damage refers to changes in DNA structure that are caused by ______.
reactive oxygen species
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
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
A mutant allele is best defined as an allele that
has a different DNA sequence from the wild-type
Translesion DNA polymerases are ______ accurate and ______ sensitive to geometric distortions in DNA than replicative DNA polymerases.
less, less
Gene conversion occurs by the action of
mismatch repair DNA gap repair synthesis
The probability that a gene will be altered by a new mutation is referred to as the
mutation rate
A mutation that does not change the amino acid sequence of a polypeptide is known as a(n) __ mutation
silent
The phenomenon in which a repeated sequence of three nucleotide bases increases in number generation after generation is called
trinucleotide repeat expansion
The removal of a purine from DNA is called
depurination
Mutations that remove an adenine or guanine from the DNA are known as
depurinations
Photoreactivation is a repair mechanism that can ______ a thymine dimer in the ______ of light.
directly split; presence
Trinucleotide repeat expansions are repeated sequences of three nucleotide bases which _
increase generation after generation
A heritable change in the genetic material is called a(n) ______.
mutation
The term __ refers to an inherited change in the sequence of the genetic material.
mutation
DNA gap repair synthesis
restores the stretches of DNA removed by strand degradation at the initiation of recombination.
