Nucleotide excision repair

Definition

Nucleotide excision repair is a critical DNA repair mechanism that removes damaged DNA segments, specifically those caused by environmental factors like UV radiation and chemical exposure. This process is vital for maintaining genomic integrity, as it prevents mutations that could lead to diseases, including cancer. By recognizing and excising bulky DNA adducts, nucleotide excision repair plays a significant role in protecting cells from genotoxicity and reducing the risk of mutagenicity and carcinogenicity.

5 Must Know Facts For Your Next Test

1. Nucleotide excision repair is crucial for fixing bulky DNA lesions, such as those formed by UV light-induced thymine dimers.
2. The mechanism involves multiple steps: damage recognition, strand unwinding, excision of the damaged segment, and synthesis of new DNA to fill the gap.
3. Defects in nucleotide excision repair are linked to disorders like xeroderma pigmentosum, which increases skin cancer risk due to impaired DNA repair.
4. Nucleotide excision repair operates in all living organisms, highlighting its fundamental role in cellular maintenance and protection against genetic damage.
5. This repair system is essential not only for preventing mutations but also for avoiding cellular aging and maintaining overall cellular health.

Review Questions

• How does nucleotide excision repair contribute to the prevention of mutations in DNA?
  • Nucleotide excision repair helps prevent mutations by identifying and removing damaged sections of DNA before they can be replicated. The mechanism recognizes bulky lesions, such as those caused by UV light or certain chemicals, and excises the damaged nucleotides. By replacing these segments with correctly synthesized DNA, this repair pathway effectively maintains the fidelity of the genetic code, thus reducing the likelihood of mutations that could lead to disease.
• Discuss the implications of defective nucleotide excision repair on human health and disease susceptibility.
  • Defective nucleotide excision repair can have severe health implications, as it compromises the cell's ability to correct DNA damage effectively. Conditions like xeroderma pigmentosum exemplify this risk, where individuals have an increased susceptibility to skin cancer due to their impaired ability to repair UV-induced DNA lesions. As a result, understanding the function of this repair pathway is essential for developing strategies to mitigate cancer risk and manage genetic disorders related to DNA repair deficiencies.
• Evaluate how understanding nucleotide excision repair mechanisms can inform therapeutic approaches in cancer treatment.
  • Understanding nucleotide excision repair mechanisms can significantly influence therapeutic strategies in cancer treatment by highlighting potential vulnerabilities in cancer cells. Many cancer therapies rely on inducing DNA damage to kill malignant cells; thus, knowledge of how these cells repair damage through nucleotide excision can help tailor treatments that either inhibit these pathways or enhance their effectiveness. By exploiting deficiencies in DNA repair mechanisms within tumors, researchers can develop more targeted and efficient therapies that minimize damage to healthy tissue while maximizing tumor cell destruction.

Related terms

DNA damage: The alteration of the DNA structure that can result from exposure to harmful agents, leading to mutations if not properly repaired.

mutagen: An agent, such as radiation or a chemical substance, that causes changes or mutations in the DNA sequence.

carcinogenesis: The process by which normal cells are transformed into cancer cells, often involving genetic mutations caused by environmental factors.