Dna repair mechanisms

Definition

DNA repair mechanisms are processes that correct damage to the DNA molecule that can occur due to environmental factors, errors during replication, or normal cellular metabolism. These mechanisms are crucial for maintaining the integrity of genetic information and ensuring proper cellular function, especially during the cell cycle where DNA is replicated and divided among daughter cells.

5 Must Know Facts For Your Next Test

1. DNA repair mechanisms play a critical role during the S phase of the cell cycle when DNA is being replicated, as errors must be corrected to prevent mutations.
2. Failure of these repair systems can lead to genetic instability, contributing to diseases such as cancer.
3. Different types of DNA damage can occur, including single-strand breaks, double-strand breaks, and base modifications, each requiring specific repair strategies.
4. The presence of functional DNA repair pathways is monitored by cell cycle checkpoints, which can halt progression if damage is detected.
5. Enzymes like DNA polymerases are involved not only in replication but also in recognizing and repairing errors during the process.

Review Questions

• How do DNA repair mechanisms interact with cell cycle checkpoints during the S phase?
  • During the S phase of the cell cycle, DNA repair mechanisms are essential for correcting errors that occur during DNA replication. Cell cycle checkpoints monitor the integrity of DNA, ensuring that any detected damage triggers repair processes before the cell can proceed to mitosis. If significant damage is present and cannot be repaired, checkpoints can induce cell cycle arrest, preventing the division of potentially harmful cells.
• Discuss the consequences of defective DNA repair mechanisms on cellular health and disease progression.
  • Defective DNA repair mechanisms can lead to an accumulation of mutations, resulting in genomic instability. This instability is a hallmark of cancer progression, as it allows for uncontrolled cell growth and division. Additionally, inherited defects in specific repair pathways can lead to genetic disorders characterized by heightened sensitivity to environmental stressors or predisposition to various cancers.
• Evaluate the role of homologous recombination in maintaining genomic stability and its implications in cancer therapy.
  • Homologous recombination is a key DNA repair mechanism that ensures accurate repair of double-strand breaks using a homologous template. Its role in maintaining genomic stability is critical as it prevents mutations from being passed on during cell division. In cancer therapy, targeting homologous recombination pathways can enhance the effectiveness of treatments such as PARP inhibitors, which exploit defects in these pathways in cancer cells to induce synthetic lethality, ultimately leading to tumor regression.

Related terms

Nucleotide Excision Repair: A DNA repair mechanism that removes and replaces damaged sections of DNA, particularly those caused by UV light or chemical exposure.

Homologous Recombination: A type of DNA repair that uses a homologous sequence as a template to accurately repair double-strand breaks in DNA.

Cell Cycle Checkpoints: Control mechanisms in the cell cycle that ensure the proper progression through phases, including the detection and repair of DNA damage before cell division.