Thymine dimer
Thymine Dimer
Thymine dimer (pronounced: /ˈθaɪmiːn ˈdaɪmər/) is a molecular lesion, or damage, that occurs in the DNA. It is formed from two adjacent thymine bases, hence the term "dimer".
Etymology
The term "Thymine dimer" is derived from the name of the nucleobase Thymine, one of the four nucleobases in the nucleic acid of DNA, and the word "dimer", which is a general term in chemistry for a molecule or molecular complex consisting of two identical molecules linked together.
Formation
Thymine dimers are most commonly caused by exposure to ultraviolet (UV) radiation. The energy from the UV light causes the formation of a covalent bond between two adjacent thymine bases in the DNA strand. This bond formation distorts the DNA molecule and interferes with normal DNA replication.
Repair
Cells have mechanisms to repair thymine dimers and other DNA damage. The most common repair mechanism for thymine dimers is Nucleotide Excision Repair (NER), a process that removes the damaged section of DNA and replaces it with the correct sequence.
Related Terms
- Nucleotide: A nucleotide is the basic building block of nucleic acids. RNA and DNA are polymers made of long chains of nucleotides.
- DNA: Deoxyribonucleic acid (DNA) is a molecule composed of two chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses.
- Ultraviolet: Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency of approximately 30 PHz) to 400 nm (750 THz), shorter than that of visible light but longer than X-rays.
- Nucleotide Excision Repair: Nucleotide excision repair (NER) is a DNA repair mechanism. DNA damage occurs constantly because of chemicals (e.g., intercalating agents, ROS) and radiation (e.g., UV light, x-rays).
External links
- Medical encyclopedia article on Thymine dimer
- Wikipedia's article - Thymine dimer
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