Genetics Reading 13

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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.


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