Genetics SB 8
Place the steps of homologous recombination repair in the proper sequence. Start with the earliest on top.
1. DSB 2. Strand Exchange ' 3. DNA Synthesis 4. Resolution
The following are steps in the nucleotide excision repair (NER) system. Place them in order, starting with the earliest on top. Instructions
1. UvrA/UvrB 2. UvrA 3. UvrC 4. UvrD 5. UvrB 6. Dna Polymerase
Which enzyme can remove methyl or ethyl groups from guanines that have been subjected to mutagens such as nitrogen mustard? Multiple choice question. Alkyltransferase Phosphotransferase Glycosylase Photolyase
Alkyltransferase
Which enzyme can remove methyl or ethyl groups from guanines that have been subjected to mutagens such as nitrogen mustard? Multiple choice question. Glycosylase Phosphotransferase Alkyltransferase Photolyase
Alkyltransferase
Double-strand breaks are typically repaired by which of the following? Multiple select question. Homologous recombination repair Methyl-directed mismatch repair Nucleotide excision repair Photoreactivation Nonhomologous end joining
Answer Homologous recombination repair Nonhomologous end joining
True or false: The nucleotide excision repair system of DNA repair is unique to prokaryotes.
False
Eukaryotic homologs for which of the following have been found so far? Multiple choice question. MutS and MutL MutS, MutL and MutH MutS and MutH MutH and MutL
MutS and MutL
The following proteins participate in mismatch repair. Match the protein with its appropriate function. Instructions
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 Exonuclease-Digests the nonmethylated strand
In the mismatch repair system, select the two Mut proteins that form a complex, activating a third Mut protein, which is already bound to a hemimethylated DNA site. Multiple choice question. MutS/MutH ; MutL MutH/MutL ; MutS MutS/MutL ; MutH
MutS/MutL ; MutH
The enzyme that can recognize thymine dimers and split them is called .
Photolyase
Which enzyme can correct the mutation shown in this figure? Multiple choice question. Phosphodiesterase Photoligase Phosphotransferase Photolyase
Photolyase
What can cause double-strand breaks (DSBs)? Multiple select question.
X-rays Reactive oxygen species Gamma rays
Base excision repair (BER) is the main system used in the repair of ______. Multiple choice question. mismatched bases single-strand breaks abnormal bases double-strand breaks
abnormal bases
The breakage of chromosomes is referred to as a(n) - break.
double strand
The strand that is repaired in the mismatch repair system is ______. Multiple choice question. the methylated strand the nonmethylated strand either the methylated or nonmethylated strand, depending on the type of mismatch either the methylated or nonmethylated strand, depending on the size of mismatch the hemimethylated strand
the nonmethylated strand
Fill in the blank question. This child has the disease which makes her more susceptible to skin cancer.
1. xeroderma 2.Pigmentosum
In an average human individual, naturally occurring double-strand breaks occur at a rate of ______ per cell per day. Multiple choice question. 1000-2000 500-1000 10-100 1-2
10-100
Which pair of proteins is required for nucleotide excision repair (NER)? Multiple choice question. UvrA and photolyase UvrD and N-glycosylase UvrB and AP endonuclease UvrC and DNA ligase
UvrC and DNA ligase
The process by which thymine dimers are directly repaired with the help of light is called .
photoreactivation
What can cause double-strand breaks (DSBs)?
Gamma rays Reactive oxygen species X-rays
True or false: During homologous recombination repair, the two broken ends of DNA are pieced back together.
False
Bacterial strains that lack one or more DNA repair systems have a very high mutation rate. These are called strains.
Mutator
In the nucleotide excision repair (NER) system, select the complex that recognizes damaged DNA, followed by the proteins that act to remove the damaged DNA. Multiple choice question. UvrA/UvrB complex; UvrC (helicase) and UvrD (endonuclease) UvrC/UvrD complex; UvrA (endonuclease) and UvrB (helicase) UvrC/UvrD complex; UvrA (helicase) and UvrB (endonuclease) UvrA/UvrB complex; UvrC (endonuclease) and UvrD (helicase)
UvrA/UvrB complex; UvrC (endonuclease) and UvrD (helicase)
Consider a DNA that has been exposed to the alkylating agent nitrogen mustard. The protein that can remove the ethyl and methyl groups from the guanine bases is called .
alkyltransferase
Error-prone replication is a characteristic of ______. Multiple choice question. polymerases of fungi telomere-replicating polymerases lesion-replicating polymerases polymerases of archaea
lesion-replicating polymerases
The strand that is repaired in the mismatch repair system is ______. Multiple choice question. the hemimethylated strand either the methylated or nonmethylated strand, depending on the size of mismatch the methylated strand either the methylated or nonmethylated strand, depending on the type of mismatch the nonmethylated strand
the nonmethylated strand
The following are steps in the base excision repair (BER) system. Place them in order, starting with the earliest on top. Instructions
1. N-glycosylase 2. Ap endonuclease 3. Dna Polymerase 4. Dna Ligase
Translesion DNA polymerases incorporate wrong nucleotides with a frequency of approximately _____, which is ______ than the error rate for replicative DNA polymerases. Multiple choice question. 10-8 ; higher 10-2 ; lower 10-2 ; higher 10-5 ; lower 10-8 ; lower
10-2 ; higher
Which polymerase is involved in the base excision repair system of eukaryotes? Multiple choice question. DNA polymerase II DNA polymerase β DNA polymerase α DNA polymerase I
DNA polymerase β
In the mismatch repair system, how is the newly-made daughter strand distinguished from the parental strand? Multiple choice question. The daughter strand is acetylated, while the parental strand is not. The daughter strand is methylated, while the parental strand is not. The parental strand is acetylated, while the daughter strand is not. The parental strand is methylated, while the daughter strand is not.
The parental strand is methylated, while the daughter strand is not.
Homologous recombination is a process in which Multiple choice question. small segments of DNA can move to multiple locations within the chromosomal DNA. a portion of one chromosome is transferred to a new location on a non-homologous chromosome. a new combination of DNA sequences is formed through breakage and rejoining of similar or identical DNA segments. the DNA of viral genomes is integrated into host cell DNA.
a new combination of DNA sequences is formed through breakage and rejoining of similar or identical DNA segments.
DNA N-glycosylases exist in many types. Which of these abnormal DNA bases can be recognized by these enzymes? Multiple select question. 7-methylguanine 3-methyladenine 5-methylthymine Uracil
7-methylguanine 3-methyladenine Uracil
This figure shows what DNA repair system? Multiple choice question. Mismatch repair Nonhomologous end joining Nucleotide excision repair Homologous recombination repair
Homologous recombination repair
Some errors create bulky distortions of the double helix. These errors are removed primarily by a DNA repair system called NER, which stands for base
nucleotide excision
Nucleotide excision repair (NER) is the main system used in the repair of ______. Multiple choice question. small, helix non-distorting lesions bulky, helix distorting lesions mismatched bases abnormal bases
bulky, helix distorting lesions
Nucleotide excision repair (NER) is the main system used in the repair of ______. Multiple choice question. small, helix non-distorting lesions mismatched bases abnormal bases bulky, helix distorting lesions
bulky, helix distorting lesions
Which of the following enzymes participate in the base excision repair system of humans? Multiple select question. AP endonuclease Alkyltransferase Flap endonuclease Photolyase N-glycosylase
AP endonuclease Flap endonuclease N-glycosylase
Which of the following are examples of base pair mismatches? Multiple select question. Adenine on parent strand and Cytosine on daughter strand Adenine on parent strand and Thymine on daughter strand Cytosine on parent strand and Adenine on daughter strand Cytosine on parent strand and Guanine on daughter strand 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 Cytosine on parent strand and Thymine on daughter strand
Which are involved in crossing over? Multiple select question. Breakage of non-sister chromatids at analogous locations Movement of DNA from one chromosome to a new location on a non-homologous chromosome Alignment of a pair of homologous chromosomes Exchange of corresponding chromosome segments Duplication of a multi-gene region within one chromosome
Breakage of non-sister chromatids at analogous locations Alignment of a pair of homologous chromosomes Exchange of corresponding chromosome segments
In the base excision repair (BER) system of E. coli, which is the enzyme that removes a DNA segment containing the abnormal region and replaces it simultaneously with normal nucleotides? Multiple choice question. DNA polymerase I DNA polymerase δ DNA polymerase β DNA polymerase ε
DNA polymerase I
In the base excision repair (BER) system of eukaryotes, which enzyme can synthesize a short segment of DNA that displaces the original DNA, and what is generated as a result? Multiple choice question. DNA polymerase δ or ε ; flap DNA polymerase α or γ ; nick DNA polymerase α or γ ; flap DNA polymerase δ or ε ; nick
DNA polymerase δ or ε ; flap
Which of the following is least likely to occur as a result of a double-strand break? Multiple choice question. Inversions Translocations Deletions Duplications
Duplications
Which recombination processes occur in bacterial cells? Multiple select question. Homologous recombination of replicated regions during DNA duplication Transfer of a DNA segment from one chromosome to a new location on a non-homologous chromosome Exchange of segments between identical copies of the bacterial chromosome within the same cell Exchange of segments between non-sister chromatids
Homologous recombination of replicated regions during DNA duplication Exchange of segments between identical copies of the bacterial chromosome within the same cell
DNA N-glycosylases participate in the base excision repair (BER) system. These enzymes ______. Multiple choice question. add a normal base remove an abnormal nucleotide remove an abnormal base add a normal nucleotide
remove an abnormal base
In the base excision repair (BER) system of E. coli, DNA polymerase I ______. Multiple select question. replaces the abnormal region with normal nucleotides removes a segment containing abnormal DNA removes a site that is missing a single base and inserts a nucleotide with the correct base in its place seals breaks in the DNA backbone synthesizes a short segment of DNA that displaces some of the original DNA, generating a flap
replaces the abnormal region with normal nucleotides removes a segment containing abnormal DNA
AP endonucleases are enzymes involved in ______. Multiple choice question. photoreactivation nucleotide excision repair homologous recombination base excision repair
base excision repair
DNA N-glycosylases are enzymes involved in ______. Multiple choice question. base excision repair homologous recombination mismatch repair photoreactivation
base excision repair
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 ______. Multiple choice question. base pair tautomer frameshift mutation dynamic mutation base pair mismatch
base pair mismatch
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 ______. Multiple choice question. base pair tautomer frameshift mutation base pair mismatch dynamic mutation
base pair mismatch
Eukaryotic species have homologs to which of the following mismatch repair proteins of E. coli? Multiple select question. MutL UvrA MutS MutH UvrB
MutL MutS
An advantage of ______ is that it provides an error-free mechanism for repairing a DNA double-strand break. Multiple choice question. the nucleotide excision repair system the mismatch repair system homologous recombination repair nonhomologous end joining
homologous recombination repair
The protein alkyltransferase can only be used once because it ______. Multiple choice question. is inactivated by the addition of a methyl group becomes permanently attached to the DNA strand is hydrolyzed in the process of repairing the DNA becomes permanently attached to the nuclear membrane
is inactivated by the addition of a methyl group
Translesion DNA polymerases are ______ accurate and ______ sensitive to geometric distortions in DNA than replicative DNA polymerases. Multiple choice question. more ; more less ; more less ; less more ; less
less ; less
When a cell repairs a double-strand DNA break by the mechanism of nonhomologous end joining, the original DNA sequence at the repair site ______. Multiple choice question. may be changed by a short addition may be changed by a small deletion may be changed by a small inversion is always reformed with 100% accuracy
may be changed by a small deletion
When a cell repairs a double-strand DNA break by the mechanism of nonhomologous end joining, the original DNA sequence at the repair site ______. Multiple choice question. may be changed by a small deletion may be changed by a small inversion may be changed by a short addition is always reformed with 100% accuracy
may be changed by a small deletion
Hereditary nonpolyposis colorectal cancer is due, in part, to defects in ______ repair. Multiple choice question. homologous recombination photoreactivation mismatch nucleotide excision base excision
mismatch
This figure shows the first steps of the mechanism of DNA repair called ______. Multiple choice question. homologous recombination repair nonhomologous end joining
nonhomologous end joining
The proteins UvrA, UvrB, UvrC, and UvrD are required for the DNA repair system called ______ repair. Multiple choice question. homologous recombination base excision methyl-directed mismatch nucleotide excision
nucleotide excision
Xeroderma pigmentosum and Cockayne syndrome are two human diseases caused by inherited defects in ______ repair. Multiple choice question. homologous recombination base excision mismatch nucleotide excision photoreactivation
nucleotide excision
Why is rat liver extract used in the Ames test for mutagenicity? Multiple choice question. Rat liver contains enzymes that can activate the mutagen. Rat liver contains proteins that can cause mutations. Rat liver contains enzymes that neutralize the mutagen. Rat liver contains proteins that can repair mutations.
Rat liver contains enzymes that can activate the mutagen.
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.
Sister Chromatid
Nucleotide excision repair (NER) is found in ______. Multiple choice question. prokaryotes but not eukaryotes eukaryotes but not prokaryotes neither eukaryotes nor prokaryotes both prokaryotes and eukaryotes
both prokaryotes and eukaryotes
The mutation shown in this figure is most likely repaired by the enzyme ______. Multiple choice question. demethylase which removes the excess methyl group alkyltransferase that transfers the methyl group onto another protein alkyltransferase that transfers the methyl group onto itself methylesterase which removes the excess methyl group
alkyltransferase that transfers the methyl group onto itself
Defects in the human mismatch repair genes, hMSH2 and hMLH1, play a role in the development of ______. Multiple choice question. systemic lupus erythematosus cockayne syndrome hereditary nonpolyposis colorectal cancer xeroderma pigmentosum
hereditary nonpolyposis colorectal cancer
The process by which chromosomes exchange similar or identical DNA segments during meiosis is called ______. Multiple choice question. site-specific recombination non-homologous recombination homologous recombination transposition heterologous recombination
homologous recombination
Translesion synthesis refers to the ______. Multiple choice question. first step of the mechanism of homologous recombination repair replication strategy employed by nucleotide excision repair (NER) proteins last step of the mechanism of nonhomologous end joining replication of a template strand that contains DNA damage
replication of a template strand that contains DNA damage
A disadvantage of homologous recombination repair in eukaryotes is that it is dependent on ______. Multiple choice question. Uvr proteins, which require sunlight for their activity Mut proteins, which lack proofreading capabilities and so are error-prone sister chromatids, which are only available during part of the cell cycle homologous DNA sequences, which form hairpin structures that hinder replication
sister chromatids, which are only available during part of the cell cycle
Which of these human diseases are caused by mutations in genes involved in nucleotide excision repair? Multiple select question. Cockayne syndrome Lejeune syndrome Dystrophia myotonica Ataxia telangiectasia Xeroderma pigmentosum
Cockayne syndrome Xeroderma pigmentosum
Which pair of proteins is required for nucleotide excision repair (NER)? Multiple choice question. UvrA and photolyase UvrD and N-glycosylase UvrC and DNA ligase UvrB and AP endonuclease
UvrC and DNA ligase
Homologous recombination that produces a new combination of alleles occurs through ______. Multiple choice question. movement of small DNA segments to new locations in chromosomal DNA insertion of viral DNA sequences into host DNA exchange of segments between sister chromatids crossover between homologous chromosomes during meiosis
crossover between homologous chromosomes during meiosis
Fill in the blank question. 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.
1. Sister 2. Chromatid
Which of the following human diseases is associated with a high predisposition to skin cancer because of an inability to repair UV-induced lesions? Multiple choice question. Keratosis cutaneum Cutaneous porphyria Xeroderma pigmentosum Epidermolysis bullosa
Xeroderma pigmentosum
Fill in the blank question. Homologous recombination that does not produce a new combination of alleles is called exchange.
1. Sister 2. Chromatid
Which of the following human diseases is associated with a high predisposition to skin cancer because of an inability to repair UV-induced lesions? Multiple choice question. Keratosis cutaneum Cutaneous porphyria Xeroderma pigmentosum Epidermolysis bullosa
Xeroderma pigmentosum
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
Homologous recombination between genetically-identical chromatids is called ______. Multiple choice question. non-homologous recombination sister chromatid exchange site-specific recombination transposition translocation
sister chromatid exchange
Fill in the blank question. Lesion-replicating polymerases lead to a high mutation rate. This phenomenon has been termed - replication.
1. error 2. prone
Fill in the blank question. The two main mechanisms used to repair DNA double-strand breaks are recombination repair and end joining.
1. homologous 2. non-homologous
Fill in the blank question. The synthesis of DNA over a template strand that harbors some type of DNA damage is called .
1. translesion 2. synthesis
Which of the following is least likely to occur as a result of a double-strand break? Multiple choice question. Inversions Deletions Translocations Duplications
Duplications
Which process leads to a new combination of alleles in the chromosomal products? Multiple choice question. Homologous recombination during meiosis Sister chromatid exchange Site-specific recombination
Homologous recombination during meiosis
Which of the following statements about DNA N-glycosylase is true? Multiple choice question. Living organisms produce many types, each of which deals with specific types of abnormal bases. Living organisms produce many types, each of which can deal with any abnormal base. Living organisms produce only one type, which can deal only with the abnormal base 7-methylguanine. Living organisms produce only one type, which can deal with any abnormal base.
Living organisms produce many types, each of which deals with specific types of abnormal bases.
Eukaryotic species have homologs to which of the following mismatch repair proteins of E. coli? Multiple select question. MutH MutL UvrB UvrA MutS
MutL MutS
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
AP endonucleases participate in the base excision repair (BER) system. These enzymes ______ an apurinic/apyrimidinic site. Multiple choice question. add a normal base, and thus fill remove an abnormal base, and thus create cut DNA on the 3' side of cut DNA on the 5' side of
cut DNA on the 5' side of
A chemical agent is being assayed for mutagenicity using the Ames test. This agent would be judged to be a mutagen if the number of bacterial colonies on the test plate is ______. Multiple choice question. zero, and any number of colonies shows up on the control plate significantly higher than that of the control plate significantly lower than that of the control plate about the same as that of the control plate
significantly higher than that of the control plate
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? Multiple choice question. Mismatch repair system Nonhomologous end joining Base excision repair Nucleotide excision repair Homologous recombination repair
Mismatch repair system
