Exploring Homologous Recombination and Nonhomologous End Joining in DNA Repair

1. Major Proteins Involved in Homologous Recombination?

Insulin Receptor

Histone Proteins

RecA, Rad51, Rad54, ATM,

DNA Polymerase

Homologous recombination is a process that involves specific proteins in DNA repair and genetic recombination, such as RecA, Rad51, Rad54, and ATM. Other proteins like DNA Polymerase, Histone Proteins, and Insulin Receptor are not primarily involved in this genetic process.

Explanation

Homologous recombination is a process that involves specific proteins in DNA repair and genetic recombination, such as RecA, Rad51, Rad54, and ATM. Other proteins like DNA Polymerase, Histone Proteins, and Insulin Receptor are not primarily involved in this genetic process.

2. What are the major events of Nonhomologous End Joining?

Telomerase extends telomeres at chromosome ends

RNA splicing removes introns from DNA sequences

Ku70/80 binds DNA ends. DNA-PK bind to Ku heterodimer and autophosphorylate. XRCC (ligas IV) ligates DNA together

DNA polymerase synthesizes new DNA strands

Nonhomologous End Joining (NHEJ) is a DNA double-strand break repair pathway in eukaryotic cells. The major events include Ku70/80 binding to DNA ends, DNA-PK binding to the Ku heterodimer and autophosphorylating, and XRCC (ligase IV) ligating the DNA ends together. The incorrect answers provided do not accurately reflect the steps involved in NHEJ.

Explanation

Nonhomologous End Joining (NHEJ) is a DNA double-strand break repair pathway in eukaryotic cells. The major events include Ku70/80 binding to DNA ends, DNA-PK binding to the Ku heterodimer and autophosphorylating, and XRCC (ligase IV) ligating the DNA ends together. The incorrect answers provided do not accurately reflect the steps involved in NHEJ.

3. Major Proteins Involved in Non-Homologous End Joining (NHEJ)

RNA Polymerase, Ribosomal Proteins, Transcription Factors

RAD51, BRCA1, WRN

Topoisomerase, Helicase, Polymerase

Ku 70/80, XRCC4-Lig4, DNA-PKs

Non-Homologous End Joining (NHEJ) is a pathway for repairing double-strand breaks in DNA. The correct answer includes Ku 70/80, XRCC4-Lig4, and DNA-PKs which are essential proteins involved in this process. The incorrect answers do not play direct roles in NHEJ pathway.

Explanation

Non-Homologous End Joining (NHEJ) is a pathway for repairing double-strand breaks in DNA. The correct answer includes Ku 70/80, XRCC4-Lig4, and DNA-PKs which are essential proteins involved in this process. The incorrect answers do not play direct roles in NHEJ pathway.

4. What causes the cell to choose Homologous Recombination?

Cell in G1 phase due to high levels of DNA repair enzymes present

Cell in M phase as it has the highest DNA repair efficiency at that stage

Cell in early S phase because of the availability of nucleotides for repair synthesis

Homologous recombination occurs in late S and G2 phase as the sister chromatid is nearby for repair and CDK1 regulates end resection. The incorrect answers provided do not align with the specific requirements of Homologous Recombination in terms of cell phase and molecular regulation.

Explanation

Homologous recombination occurs in late S and G2 phase as the sister chromatid is nearby for repair and CDK1 regulates end resection. The incorrect answers provided do not align with the specific requirements of Homologous Recombination in terms of cell phase and molecular regulation.

5. What are the HR pathways?

TGF-B:FGF:TGF-RA:BMP:Wnt:

DSBR:SDSA:SSA:BIR:RecF:

CIO:CTO:COO:CFO:CEO:

HRM:CRM:HCM:ER:OD:

The correct HR pathways are DSBR:SDSA:SSA:BIR:RecF:, which stands for Double-strand break repair:Single-strand annealing:Single-strand annealing:Bulge intermediate resolution:RecF protein.

Explanation

The correct HR pathways are DSBR:SDSA:SSA:BIR:RecF:, which stands for Double-strand break repair:Single-strand annealing:Single-strand annealing:Bulge intermediate resolution:RecF protein.

6. What causes the cell to choose NHEJ?

Only occurs in G2 phase of the cell cycle.

NHEJ functions primarily during apoptosis.

NHEJ is only utilized in specialized cell types.

NHEJ is known for its quick repair abilities and flexibility to operate in all stages of the cell cycle, with a major focus on repair in G0/G1 phases. It is not limited to G2 phase, specific cell types, or apoptosis.

Explanation

NHEJ is known for its quick repair abilities and flexibility to operate in all stages of the cell cycle, with a major focus on repair in G0/G1 phases. It is not limited to G2 phase, specific cell types, or apoptosis.

7. What is a major requirement in Homologous Recombination?

End Resection only a requirement in HR

Single-strand annealing

Non-homologous end joining

Homology searching

End Resection is a critical step in homologous recombination process for generating long 3' single-stranded DNA tails for strand invasion and DNA repair.

Explanation

End Resection is a critical step in homologous recombination process for generating long 3' single-stranded DNA tails for strand invasion and DNA repair.