Quiz 2: DNA Damage, Repair And Recombination
Section F – DNA damage, repair andrecombination
F1 Mutagenesis
F2 DNA damage
F3 DNA Repair
F4 Recombination
ACARA PRESENTASI KELOMPOK, Selasa, 18 Mei 2010
1. Presenter Kelompok 3 (Penyanggah Kelompok 5): Topik Mutations
2. Presenter Kelompok 4 (Penyanggah Kelompok 6): Topik DNA Repair
- 1.
Which of the following is TRUE about mutation
- A.
Acceptable variations in the ‘normal’ DNA and protein sequences
- B.
The exchange of DNA between chromosomes during meiosis.
- C.
The movement of a ribosome from one reading frame to another at an internal position within a gene
- D.
A DNA repair process that corrects various types of DNA damage by excising and resynthesizing a region of polynucleotide
- E.
Permanent, heritable alterations in the base sequence of the DNA.
Correct Answer
E. Permanent, heritable alterations in the base sequence of the DNA.Explanation
Mutation refers to permanent, heritable alterations in the base sequence of the DNA. This means that the DNA sequence is permanently changed, and this alteration can be passed on to future generations. Mutations can occur due to various factors such as errors during DNA replication or exposure to certain chemicals or radiation. These alterations in the DNA sequence can lead to changes in the protein produced, which can have significant effects on an organism's phenotype and evolution.Rate this question:
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- 2.
Mutations arise through spontaneous__________ I. in DNA replication II. in meiotic recombination III. as a consequence of the damaging effects of physical or chemical agents on the DNA
- A.
I only
- B.
II only
- C.
III only
- D.
I and II
- E.
I, II, and III
Correct Answer
E. I, II, and IIIExplanation
Mutations can arise through spontaneous processes in DNA replication, in meiotic recombination, and as a consequence of the damaging effects of physical or chemical agents on the DNA. This means that mutations can occur during the normal replication of DNA, during the process of meiotic recombination which shuffles genetic material during the formation of reproductive cells, and as a result of external factors such as exposure to radiation or certain chemicals that can cause damage to the DNA. Therefore, all three options I, II, and III are correct.Rate this question:
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- 3.
An alteration in a nucleotide sequence that changes a triplet coding for an amino acid into a termination codon.
- A.
Nonsense mutation
- B.
Mutation
- C.
Mutagenesis
- D.
Mutagen
- E.
Missense mutation
Correct Answer
A. Nonsense mutationExplanation
A nonsense mutation refers to a genetic alteration in a nucleotide sequence that causes a triplet coding for an amino acid to be changed into a termination codon. This means that instead of coding for an amino acid, the mutated sequence signals the end of protein synthesis. This type of mutation often leads to the production of nonfunctional or truncated proteins, which can have significant effects on an organism's phenotype.Rate this question:
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- 4.
A point mutation that replaces a purine with another purine, or a pyrimidine with another pyrimidine.
- A.
Transition
- B.
Transversion
- C.
Nonsense
- D.
Silent mutation
- E.
Missense mutation
Correct Answer
A. TransitionExplanation
Transition is the correct answer because it refers to a specific type of point mutation where a purine (adenine or guanine) is replaced by another purine, or a pyrimidine (thymine or cytosine) is replaced by another pyrimidine. This type of mutation does not change the amino acid sequence of the resulting protein, making it a conservative mutation.Rate this question:
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- 5.
A point mutation that involves a purine being replaced by a pyrimidine, or vice versa.
- A.
Transition
- B.
Transversion
- C.
Nonsense
- D.
Silent mutation
- E.
Missense mutation
Correct Answer
B. TransversionExplanation
A transversion is a type of point mutation where a purine (adenine or guanine) is replaced by a pyrimidine (cytosine or thymine), or vice versa. This mutation can cause a change in the DNA sequence, leading to alterations in the corresponding protein sequence. Transversions are considered more rare than transitions, which involve the replacement of one purine with another or one pyrimidine with another.Rate this question:
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- 6.
A change in a DNA sequence that has no effect on the expression or functioning of any gene or gene product.
- A.
Transition
- B.
Transversion
- C.
Nonsense
- D.
Silent mutation
- E.
Missense mutation
Correct Answer
D. Silent mutationExplanation
A silent mutation refers to a change in the DNA sequence that does not result in any observable change in the expression or functioning of a gene or gene product. This means that even though the DNA sequence has been altered, the resulting protein remains unchanged, and there is no impact on the organism's phenotype. Silent mutations often occur in the third position of a codon, where changes in the DNA sequence do not affect the amino acid that is encoded.Rate this question:
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- 7.
An alteration in a nucleotide sequence that converts a codon for one amino acid into a codon for a second amino acid.
- A.
Transition
- B.
Transversion
- C.
Nonsense
- D.
Silent mutation
- E.
Missense mutation
Correct Answer
E. Missense mutationExplanation
A missense mutation refers to a change in a nucleotide sequence that results in the substitution of one amino acid with another in the encoded protein. This alteration in the codon sequence leads to the incorporation of a different amino acid during protein synthesis. Unlike silent mutations that do not affect the final protein product, missense mutations can have functional consequences, potentially altering the structure and function of the protein. Therefore, a missense mutation is the correct answer as it accurately describes the given scenario of a nucleotide sequence alteration leading to a change in the encoded amino acid.Rate this question:
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- 8.
The frameshift mutations in genes can be produced by _________ I. transition II. deletetion III. insertion
- A.
I only
- B.
II only
- C.
III only
- D.
I and II
- E.
II and III
Correct Answer
E. II and IIIExplanation
Frameshift mutations occur when the reading frame of a gene is disrupted, causing a shift in the way the genetic code is read. This can be caused by deletions, where one or more nucleotides are removed from the gene sequence, or insertions, where one or more nucleotides are added to the gene sequence. Transition mutations, which involve the substitution of one nucleotide for another, do not typically cause frameshift mutations. Therefore, the correct answer is II and III, as both deletions and insertions can result in frameshift mutations.Rate this question:
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- 9.
An alteration to the normal chemical or physical structure of the DNA.
- A.
Transition
- B.
Transversion
- C.
Nonsense
- D.
Lesion
- E.
Missense mutation
Correct Answer
D. LesionExplanation
A lesion refers to an alteration or damage to the normal chemical or physical structure of DNA. It can be caused by various factors such as environmental factors, radiation, or errors during DNA replication. Lesions can lead to mutations in the DNA sequence, which can have various effects on gene expression and protein function. Therefore, the given answer is "Lesion".Rate this question:
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- 10.
5-Bromouracil is an analog of ___________ that can react with deoxyribonucleic acid to produce a polymer with increased susceptibility to mutation.
- A.
Thymine
- B.
Guanine
- C.
Cytosine
- D.
Uracil
- E.
Adenine
Correct Answer
A. ThymineExplanation
5-Bromouracil is an analog of thymine that can react with deoxyribonucleic acid to produce a polymer with increased susceptibility to mutation. This means that when 5-Bromouracil is present in DNA, it can cause changes in the DNA sequence during replication, leading to mutations. Thymine is one of the four nucleotide bases found in DNA, and by being an analog of thymine, 5-Bromouracil can substitute thymine in DNA, disrupting the normal base pairing and increasing the likelihood of mutations.Rate this question:
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- 11.
Cyclobutane pyrimidine dimers can be monomerized again by ________ in the presence of visible light.
- A.
Exonuclease
- B.
DNA photolyases
- C.
Transposase
- D.
DNA polymerase
- E.
Integrase
Correct Answer
B. DNA pHotolyasesExplanation
Cyclobutane pyrimidine dimers are formed when two adjacent pyrimidine bases in DNA are covalently bonded due to exposure to UV radiation. These dimers can be monomerized again, meaning the bond between the pyrimidine bases can be broken, by a process called photoreactivation. DNA photolyases are enzymes that are capable of performing this photoreactivation process in the presence of visible light. Therefore, DNA photolyases are the correct answer for this question.Rate this question:
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- 12.
All transposons encode a _________ which catalyzes the insertion.
- A.
DNA glycosylase
- B.
Excisionase
- C.
Transposase
- D.
DNA polymerase
- E.
Integrase
Correct Answer
C. TransposaseExplanation
Transposons are genetic elements that can move from one location to another within a genome. They encode a specific enzyme called transposase, which catalyzes the process of insertion, allowing the transposon to be integrated into a new genomic location. The other options listed, such as DNA glycosylase, excisionase, DNA polymerase, and integrase, are not directly involved in the insertion process of transposons.Rate this question:
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- 13.
Small DNA sequences that can move to virtually any position in a cell’s genome.
- A.
Exons
- B.
Introns
- C.
Egulons
- D.
LTRs
- E.
Transposons
Correct Answer
E. TransposonsExplanation
Transposons are small DNA sequences that have the ability to move to different positions within a cell's genome. They can "transpose" or jump from one location to another, making them capable of moving to virtually any position in the genome. This mobility allows transposons to potentially have significant effects on gene expression and genome evolution.Rate this question:
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- 14.
In base excision repair, the lesion is removed by __________
- A.
DNA glycosylase
- B.
Excisionase
- C.
Transposase
- D.
DNA polymerase
- E.
Integrase
Correct Answer
A. DNA glycosylaseExplanation
In base excision repair, the lesion is removed by DNA glycosylase. DNA glycosylase is an enzyme that recognizes and removes damaged or incorrect bases from the DNA molecule. It specifically recognizes and cleaves the glycosidic bond between the damaged base and the sugar-phosphate backbone, resulting in the removal of the damaged base. This repair process is important for maintaining the integrity of the DNA molecule and preventing the accumulation of mutations.Rate this question:
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- 15.
In nucleotide excision repair, an endonuclease makes nicks on either side of the lesion, which is then removed to leave a gap. This gap is filled by __________ to makes the final phosphodiester bond. I.DNA polymerase II.DNA ligase III. DNA glycolase
- A.
I only
- B.
II only
- C.
III only
- D.
I and II
- E.
I, II, and III
Correct Answer
D. I and IIExplanation
In nucleotide excision repair, an endonuclease creates nicks on both sides of the lesion, removing the damaged portion. This creates a gap in the DNA strand. The gap is then filled by DNA polymerase, which adds new nucleotides to the strand, and DNA ligase, which seals the newly synthesized DNA to the existing strand by forming a phosphodiester bond. Therefore, both DNA polymerase and DNA ligase are involved in filling the gap and making the final phosphodiester bond.Rate this question:
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- 16.
Which of the following common examples of alkylating agents.
- A.
Methylmethane sulfonate (MMS)
- B.
Ethylnitrosourea (ENU)
- C.
Nitrous acid
- D.
A and B
- E.
A, B, and C
Correct Answer
D. A and BExplanation
The correct answer is A and B. Methylmethane sulfonate (MMS) and ethylnitrosourea (ENU) are both examples of alkylating agents. Alkylating agents are compounds that can add alkyl groups to DNA, causing damage to the DNA structure and interfering with DNA replication and transcription. Nitrous acid is not an alkylating agent, as it does not add alkyl groups to DNA. Therefore, the correct answer is A and B.Rate this question:
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- 17.
The exchange of nonhomologous regions of DNA at specific sites is independent of _________
- A.
IS elements
- B.
Illegitimate recombination
- C.
Retrotransposons
- D.
RecA
- E.
General recombination
Correct Answer
D. RecAExplanation
The correct answer is recA because recA is a gene that plays a key role in general recombination, which is the exchange of homologous regions of DNA between two DNA molecules. However, the question asks for the exchange of nonhomologous regions of DNA, which is known as illegitimate recombination. Illegitimate recombination is independent of recA and instead involves other factors such as IS elements and retrotransposons.Rate this question:
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- 18.
The dispersed repetitive sequences found in higher eukaryotic DNA (e.g. LINES and SINES) probably spread through the genome by _________
- A.
Transposition
- B.
Homologous recombination
- C.
Site-specific recombination
- D.
Replication
- E.
General recombination
Correct Answer
A. TranspositionExplanation
The dispersed repetitive sequences found in higher eukaryotic DNA, such as LINES and SINES, are likely to spread through the genome by transposition. Transposition refers to the process by which these sequences can move from one location to another within the genome. This movement can occur through mechanisms such as "copy and paste" or "cut and paste," allowing the sequences to be duplicated and inserted into new genomic locations. Transposition is a common mechanism for the expansion and diversification of repetitive sequences in eukaryotic genomes.Rate this question:
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- 19.
The enzyme of Escherichia coli is a nuclease that initiates the repair of double-stranded DNA breaks by homologous recombination.
- A.
RNA polymerase
- B.
DNA polymerase
- C.
DNA ligase
- D.
RecBCD
- E.
DNA glycolase
Correct Answer
D. RecBCDExplanation
RecBCD is the correct answer because it is an enzyme in Escherichia coli that plays a crucial role in repairing double-stranded DNA breaks through homologous recombination. This enzyme acts as a nuclease, meaning it can cleave DNA, and it is involved in the initial steps of DNA repair by generating single-stranded DNA ends that can be used for recombination. RNA polymerase is responsible for synthesizing RNA from a DNA template, DNA polymerase is involved in DNA replication, DNA ligase is responsible for joining DNA fragments, and DNA glycolase is involved in DNA repair by removing damaged bases.Rate this question:
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- 20.
Which of the following DNA mutation that result in the appearance of a stop codon in the resulting mRNA. synthesis.
- A.
Transition
- B.
Transversion
- C.
Nonsense
- D.
Silent mutation
- E.
Missense mutation
Correct Answer
C. NonsenseExplanation
A nonsense mutation is a type of DNA mutation that results in the appearance of a stop codon in the resulting mRNA synthesis. This stop codon prematurely terminates the translation process, leading to the production of a truncated or non-functional protein. Nonsense mutations can have significant effects on protein structure and function, and are often associated with genetic disorders.Rate this question:
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