Uv radiation

Definition

Ultraviolet (UV) radiation is a form of electromagnetic radiation with wavelengths shorter than visible light, specifically from about 10 nm to 400 nm. This type of radiation is known to cause damage to DNA, leading to various mutations and ultimately contributing to processes like skin cancer and other cellular malfunctions.

5 Must Know Facts For Your Next Test

1. UV radiation is categorized into three types: UVA, UVB, and UVC, with UVC being the most harmful but mostly absorbed by the Earth's atmosphere.
2. When UV radiation hits DNA, it can cause the formation of thymine dimers, which disrupt the normal structure and function of the DNA.
3. Cells have evolved several mechanisms to repair UV-induced DNA damage, including nucleotide excision repair (NER) which removes damaged sections and synthesizes new DNA.
4. Excessive UV exposure can lead to an increased risk of skin cancers, as well as premature aging of the skin due to cumulative DNA damage.
5. Protective measures against UV radiation include using sunscreen, wearing protective clothing, and avoiding excessive sun exposure during peak hours.

Review Questions

• How does UV radiation specifically induce mutations in DNA?
  • UV radiation induces mutations primarily through the formation of thymine dimers in DNA. When adjacent thymine bases absorb UV light, they can bond together instead of pairing with their complementary adenines. This mispairing leads to errors during DNA replication, resulting in permanent mutations if not repaired. Understanding this process is crucial for studying how environmental factors contribute to genetic alterations and diseases like cancer.
• Discuss the role of nucleotide excision repair in counteracting the effects of UV radiation on DNA.
  • Nucleotide excision repair (NER) plays a vital role in fixing UV-induced DNA damage. When thymine dimers are formed, NER identifies these distortions and excises the damaged section of DNA. The gap is then filled with new nucleotides synthesized by DNA polymerase and sealed by DNA ligase. This repair mechanism is essential for maintaining genomic stability and preventing mutations that could lead to cancer.
• Evaluate the long-term implications of chronic UV exposure on human health and its relevance to public health strategies.
  • Chronic exposure to UV radiation has serious long-term implications for human health, primarily increasing the risk of skin cancers such as melanoma and non-melanoma types. Public health strategies must focus on educating people about the dangers of excessive sun exposure, promoting protective measures like sunscreen use and seeking shade. Additionally, understanding how UV radiation contributes to skin aging helps emphasize the importance of preventative actions throughout life. These strategies aim to reduce disease incidence and improve overall public health outcomes.

Related terms

DNA Repair Mechanisms: Biological processes that identify and correct damage to the DNA molecules that encode the genome, ensuring the integrity of genetic information.

Mutagenesis: The process by which changes in the DNA sequence can occur due to external factors, including UV radiation, resulting in mutations.

Thymine Dimers: Specific DNA lesions formed when UV radiation causes covalent bonds to form between adjacent thymine bases in DNA, disrupting normal base pairing and replication.