Thymine dimer

Definition

A thymine dimer is a type of DNA damage caused by ultraviolet (UV) radiation in which two adjacent thymine bases bond together, disrupting normal DNA structure. This can lead to mutations if not repaired.

5 Must Know Facts For Your Next Test

1. Thymine dimers are primarily induced by UVB light from the sun.
2. They cause a kink or distortion in the DNA helix, which can interfere with replication and transcription processes.
3. If unrepaired, thymine dimers can result in mutations that may lead to skin cancers like melanoma.
4. Cells repair thymine dimers through nucleotide excision repair (NER) mechanisms.
5. Thymine dimer formation is one reason why sunscreens are important for protecting skin from UV damage.

Review Questions

• What causes the formation of thymine dimers in DNA?
• How do thymine dimers affect the structure and function of DNA?
• What cellular mechanism repairs thymine dimers?

Related terms

Nucleotide Excision Repair: A DNA repair mechanism that removes bulky lesions such as thymine dimers.

Mutation: A permanent alteration in the DNA sequence that can be caused by errors during replication or external factors like UV light.

Ultraviolet Radiation: A type of electromagnetic radiation from the sun that has enough energy to cause chemical changes such as forming thymine dimers in DNA.