DNA Damage

Definition

DNA damage refers to alterations in the chemical structure of DNA that can impede replication and transcription, ultimately leading to cell injury or death. This damage can occur due to various factors including environmental stressors, radiation, and chemical exposure, which disrupt cellular functions and contribute to disease processes such as cancer and aging.

5 Must Know Facts For Your Next Test

1. DNA damage can be caused by external factors like UV radiation, chemicals, and ionizing radiation, as well as internal factors such as reactive oxygen species generated during cellular metabolism.
2. There are different types of DNA damage, including single-strand breaks, double-strand breaks, base modifications, and cross-linking of DNA strands, each with varying implications for cell survival.
3. Cells possess multiple repair mechanisms, including base excision repair (BER), nucleotide excision repair (NER), and homologous recombination, which work to fix DNA damage and prevent mutations.
4. If DNA damage is not repaired accurately, it can lead to genomic instability and increase the risk of developing cancer or other diseases.
5. The p53 protein plays a critical role in sensing DNA damage; it can halt the cell cycle for repair processes or initiate apoptosis if the damage is irreparable.

Review Questions

• How does DNA damage contribute to cellular injury, and what are some common causes of this damage?
  • DNA damage contributes to cellular injury by disrupting the normal functions of replication and transcription, which are essential for cell survival and function. Common causes include environmental stressors like UV light and chemical pollutants, as well as endogenous factors like reactive oxygen species. This damage can lead to mutations or cellular death if not properly repaired.
• Discuss the mechanisms by which cells repair DNA damage and the consequences of failure in these repair systems.
  • Cells utilize various repair mechanisms such as base excision repair (BER) and homologous recombination to fix different types of DNA damage. When these systems fail or are overwhelmed by excessive damage, it can lead to uncorrected mutations or genomic instability. This can result in cellular dysfunction or contribute to the development of diseases such as cancer, highlighting the importance of effective DNA repair pathways.
• Evaluate the implications of unrepaired DNA damage on long-term health outcomes in individuals exposed to carcinogens.
  • Unrepaired DNA damage significantly increases the risk of developing cancer and other health issues due to the accumulation of mutations over time. When individuals are exposed to carcinogens, the likelihood of DNA damage rises sharply; if these lesions are not adequately repaired, they may lead to malignant transformations. The connection between persistent DNA damage and long-term health emphasizes the need for effective preventive strategies against exposure to known carcinogens and highlights the importance of robust DNA repair mechanisms in maintaining genomic integrity.

Related terms

Mutagenesis: The process by which changes in the DNA sequence occur, often as a result of DNA damage, leading to mutations that may affect cell function or contribute to disease.

Apoptosis: A programmed cell death mechanism that is activated in response to severe DNA damage, allowing the organism to eliminate cells that may pose a threat due to potential malignancy.

Repair Mechanisms: Biochemical pathways within cells designed to detect and repair DNA damage, thus maintaining genomic stability and preventing the progression of diseases.