ch 19
Translesion DNA polymerases have an error rate of about ______, which is much ______ than replicative polymerases. Multiple choice question. 10-2 or 10-3; lower
10-2 or 10-3; higher
What can cause a frameshift mutation?
A nucleotide deletion A nucleotide addition
11 base pair sequence. For one strand: 5'-AACGCTAGATC-3' changed to 5'-AACGCGCGATC-3'. Change of T,A base pair to G,C base pair at position 6. Length unchanged.
Base substitution
The region where two chromosome pieces break and re-attach to other chromosome pieces is called a chromosomal .
Blank 1: breakpoint
The breakage of chromosomes is referred to as a(n) - break.
Blank 1: double or double strand Blank 2: strand, stranded, double strand, or strands
The addition or deletion of a number of bases that is not a multiple of 3 causes a(n) mutation.
Blank 1: frameshift, frame-shift, or frame shift
Which of these represents the correct order of steps during a typical DNA repair system?
Detection → Removal → Replication
True or false: Deleterious mutations that cause the death of a cell are called nonsense mutations.
False
What is the effect of a suppressor mutation?
It suppresses the phenotypic effect of another mutation.
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
Double-strand breaks are typically repaired by which of the following?
Nonhomologous end joining Homologous recombination repair
What type of mutations involve a change from a normal codon to a stop codon?
Nonsense mutations
A germ-line mutation is one that occurs in
a sperm or egg cell.
Hot spots are regions of the chromosome that
are more likely to mutate than other regions.
Replica plating is a technique in which
bacterial colonies are transferred from one plate to another with a sterile piece of velvet cloth.
A mutation that enhances the survival and/or reproductive success of an individual is referred to as a(n) ______ mutation.
beneficial
The following are steps in the nucleotide excision repair (NER) system. Place them in order, starting with the earliest on top.
damaged DNA Released binds Marcks removes released seals
Silent mutations are possible because the genetic code is
degenerate.
The proteins UvrA, UvrB, UvrC, and UvrD are required for the DNA repair system called
nucleotide excision repair.
A(n) ______ mutation refers to a mutation in which just one base is changed within the DNA sequence.
point
The wild type genotype or phenotype is the one that is
typically found in nature.
A breakpoint refers to the region
where two chromosome pieces break and rejoin with other chromosome pieces.
True or false: It is healthy for a human to acquire new DNA mutations, because they are the driving force for adaptive evolution.
False
The enzyme that can recognize thymine dimers and split them is called .
Blank 1: photolyase
Eukaryotic homologs for which of the following have been found so far?
MutS and MutL
What is responsible for silent mutations?
The degeneracy of the genetic code
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
In the nucleotide excision repair (NER) system, the damaged DNA is recognized by the ______, and removed by the action of the proteins ______.
UvrA/UvrB complex; UvrC (endonuclease) and UvrD (helicase)
Which pair of proteins is required for nucleotide excision repair (NER)?
UvrC and DNA ligase
What can cause double-strand breaks (DSBs)?
X-rays Gamma rays Reactive oxygen species
Nucleotide excision repair (NER) is found in
both prokaryotes and eukaryotes.
If an individual possesses a germ-line mutation, then ______ of the gametes produced by the individual will carry the mutation. If an individual possesses a somatic mutation, then ______ of the gametes produced by the individual will carry the mutation.
half; none
A new mutation in a gene is MOST LIKELY to be ______ to the organism.
harmful
When a cell repairs a double-strand DNA break by the mechanism of nonhomologous end joining, the original DNA sequence at the repair site
may be changed by a small deletion.
A mutation in a gene that causes an amino acid change in the encoded protein is called a
missense mutation.
A silent mutation is a mutation that results in
no change to the amino acid sequence of the polypeptide
The term germ line is used to describe
the cells that produce sperm and eggs.
The strand that is repaired in the mismatch repair system is
the nonmethylated strand.
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 enzyme can correct the mutation shown in this figure?
Photolyase
What feature is common to diseases caused by defects in the NER system?
Sensitivity to sun damage
The restoration of function by a second mutation at a different site in the same gene is known as a(n)
intragenic suppressor.
If the patch of white hair in this child were larger, that would indicate a ______.
somatic mutation that occurred earlier during embryonic development
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.
Blank 1: suppressor
An allele that has a DNA sequence different from that of the wild type is called a(n) allele.
Blank 1: mutant
This figure shows the first steps of the mechanism of DNA repair called .
Blank 1: nonhomologous or non-homologous Blank 2: end Blank 3: joining
A mutation that results in a premature termination of the synthesis of a polypeptide is called a(n) mutation.
Blank 1: nonsense or non-sense
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.
Blank 1: nucleotide or nucleotide excision Blank 2: excision
A change in a single base pair in the genetic material is known as a(n) mutation.
Blank 1: point, point mutation, or points
The eye color gene in this Drosophila mutant (panel B) has been relocated to a heterochromatic chromosomal region, which results in its inactivation in some cells, causing a variegated appearance. This change in the gene's location is said to have a(n) .
Blank 1: position Blank 2: effect
A mutation is one that converts a mutant allele back to the wild type form.
Blank 1: reverse or reversion
A mutation that does not change the amino acid sequence of a polypeptide is known as a(n) mutation.
Blank 1: silent
In the mismatch repair system, the proteins ______ form a complex that activates _____, which is already bound to a ______ DNA site.
MutS/MutL ; MutH ; hemimethylated
Which of these mutations changes a mutant allele back to a wild type allele?
Reversion
The embryo on the left carries a germ-line mutation; the one on the right carries a somatic mutation. Which embryo(s) will be able to pass this mutation on to future progeny?
The embryo on the left
In the mismatch repair system, how is the newly-made daughter strand distinguished from the parental strand?
The parental strand is methylated, while the daughter strand is not.
Which of these human diseases are caused by mutations in genes involved in nucleotide excision repair?
Xeroderma pigmentosum Cockayne syndrome
Examples of somatic mutations include a mutation occurring in a(n)
brain cell. adult muscle cell. embryonic kidney cell.
Nucleotide excision repair (NER) is the main system used in the repair of
bulky, helix distorting lesions.
True or false: During homologous recombination repair, the two broken ends of DNA are pieced back together.
f
True or false: The nucleotide excision repair system of DNA repair is unique to prokaryotes.
f
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
Translesion DNA polymerases are ______ accurate and ______ sensitive to geometric distortions in DNA than replicative DNA polymerases.
less ; less
The patch of white hair in this child is most likely caused by a ______ mutation.
somatic
Muscle cells, nerve cells, skin cells are examples of
somatic cells.
Mutations in body cells that do not go on to form gametes are known as
somatic mutations.
A deleterious mutation is best defined as one that decreases the chance of
survival and reproduction.
Translesion synthesis refers to
the replication of a template strand that contains DNA damage.
A deleterious mutation that results in the death of an organism is known as a(n) mutation.
Blank 1: lethal
In this figure, the Xs represent mutations in two different protein subunits. The second mutation restores function. What concept does this represent?
Intergenic suppression
The following proteins participate in mismatch repair. Match the protein with its appropriate function.
MutS Detects the mismatch MutL Acts as a linker that helps loop the DNA MutH Makes a cut in a nonmethylated strand MutU Separates strands at the cleavage site Separates strands at the cleavage site Exonuclease matches Choice, Digests the nonmethylated strand Digests the nonmethylated strand
Cells that give rise to the gametes such as eggs and sperm are called .
Blank 1: germ Blank 2: line or cells
In this figure, the Xs represent amino acids that are altered due to mutation in a transporter gene. In the last panel, transport is restored due to a(n) mutation.
Blank 1: intragenic Blank 2: suppressor
A base substitution in DNA that ultimately leads to a change in the encoded amino acid is called a(n) mutation.
Blank 1: missense or mis-sense
In a natural population, a - genotype is the most common one.
Blank 1: wild or wild type Blank 2: type
Which of the following are examples of base pair mismatches?
Cytosine on parent strand and Adenine on daughter strand Cytosine on parent strand and Thymine on daughter strand Adenine on parent strand and Cytosine on daughter strand
A change of one base for another is described as a base mutation.
Blank 1: substitution or point
Areas within a single gene that are more likely to mutate than other regions are called .
Blank 1: hot Blank 2: spots
Suppressor mutations that occur within the same gene as the first are called suppressors.
Blank 1: intragenic
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.
Blank 1: mismatch
The synthesis of DNA over a template strand that harbors some type of DNA damage is called .
Blank 1: translesion Blank 2: synthesis or replication
Mutations that occur in a promoter sequence can be divided into two types: promoter mutations increase the transcription rate, while promoter mutations decrease it.
Blank 1: up Blank 2: down
The two main mechanisms used to repair DNA double-strand breaks are recombination repair and end joining.
Blank 1: homologous Blank 2: nonhomologous or non-homologous
A main advantage of nonhomologous end joining is that it does not require a(n) , and thus it can take place throughout the cell cycle.
Blank 1: sister Blank 2: chromatid
Eukaryotic species have homologs to which of the following mismatch repair proteins of E. coli?
MutL MutS
A mutant allele is best defined as an allele that
has a different DNA sequence from the wild type.
The expression of an intact gene may be altered when it is moved to a new location. This is due to a(n) ______.
position effect
Cells of the body other than germ-line cells are called ______ cells.
somatic
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.
