A Review of DNA Repair Mechanisms: Nucleotide Excision Repair, Base Excision Repair, and Mismatch

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"Question: What is nucleotide excision repair?
Answer: Nucleotide excision repair is a DNA repair mechanism in which specific endonucleases remove the oligonucleotides containing damaged bases. DNA polymerase and ligase fill and reseal the gap, respectively. This repair mechanism repairs bulky helix-distorting lesions such as pyrimidine dimers. It occurs in G1 phase of cell cycle and is defective in xeroderma pigmentosum.Question: What are the symptoms of xeroderma pigmentosum?
Answer: Xeroderma pigmentosum presents with dry skin, photosensitivity, and skin cancer.Question: What is base excision repair?
Answer: Base excision repair is a DNA repair mechanism in which base-specific glycosylase removes an altered base and creates an AP site. One or more nucleotides are removed by AP-endonuclease, which cleaves the 5′ end. AP lyase cleaves the 3′ end. DNA polymerase-β fills the gap and DNA ligase seals it. This repair mechanism occurs throughout the cell cycle and is important in repairing spontaneous or toxic deamination.Question: What is the acronym for remembering the key steps in Base Excision Repair?
Answer: ""GEL Please.""Question: What is mismatch repair?
Answer: Mismatch repair is a DNA repair mechanism in which mismatched nucleotides in the newly synthesized strand are removed and the gap is filled and resealed. This repair mechanism occurs predominantly in the S phase of the cell cycle and is defective in Lynch syndrome. Question: How does nucleotide excision repair repair bulky helix-distorting lesions?
Answer: Nucleotide excision repair uses specific endonucleases to remove the oligonucleotides containing damaged bases, then DNA polymerase and ligase fill and reseal the gap. This repair mechanism is able to repair bulky helix-distorting lesions such as pyrimidine dimers.Question: When does nucleotide excision repair occur in the cell cycle?
Answer: Nucleotide excision repair occurs in the G1 phase of the cell cycle.Question: What is the defect that occurs in xeroderma pigmentosum?
Answer: Xeroderma pigmentosum is a defect in the ability to repair DNA pyrimidine dimers caused by UV exposure.Question: What is the function of base-specific glycosylase in base excision repair?
Answer: In base excision repair, base-specific glycosylase removes an altered base and creates an AP site (apurinic/apyrimidinic).Question: What are the steps of base excision repair?
Answer: The steps of base excision repair are: a base-specific glycosylase removes an altered base and creates an AP site, one or more nucleotides are removed by AP-endonuclease, which cleaves the 5′ end, AP lyase cleaves the 3′ end, DNA polymerase-β fills the gap and DNA ligase seals it.Question: What is the function of mismatch repair?
Answer: Mismatch repair is a DNA repair mechanism in which mismatched nucleotides in the newly synthesized strand are removed and the gap is filled and resealed.Question: When does mismatch repair occur in the cell cycle?
Answer: Mismatch repair occurs predominantly in the S phase of the cell cycle.Question: What is the defect that occurs in Lynch syndrome?
Answer: The defect that occurs in Lynch syndrome is a malfunction in the mismatch repair mechanism. Question: What is the purpose of DNA repair mechanisms like nucleotide excision repair, base excision repair, and mismatch repair?
Answer: DNA repair mechanisms like nucleotide excision repair, base excision repair, and mismatch repair are essential for maintaining the integrity of the genetic information in cells. They work to identify and correct errors and damage in the DNA, allowing the cell to continue functioning properly and avoiding the harmful effects of mutations.Question: What is the difference between nucleotide excision repair and base excision repair?
Answer: Nucleotide excision repair and base excision repair are both DNA repair mechanisms, but they differ in the types of damage they repair and the enzymes and processes used. Nucleotide excision repair is used to repair bul"