A product of ultraviolet irradiation of thymine (free in ice or bound in nucleic acids) in which two thymine residues become linked by formation of a cyclobutane ring involving both C-5's and both C-6's at the expense of the two double bonds; several stereoisomeric forms are possible.hymine dimer.
thy·mine di·mer. a product of ultraviolet irradiation of thymine (free in ice or bound in nucleic acids) in which two thymine residues become linked by formation of a cyclobutane ring involving both C-5's and both C-6's at the expense of the two double bonds; several stereoisomeric forms are possible.  Under specific conditions, such as exposure to ultraviolet light, thymine dimers may also occur, although this is much less common that the thymine-adenine pairing. In most cases, thymine is not present in RNA structures because it is replaced by uracil. It is one of the pyrimidine bases found in the nucleic acid of DNA, along with adenine, guanine and cytosine (A, G and C). These bases are the building blocks of DNA and life form on earth. One of the common mutations of DNA involves two adjacent thymines or cytosine, which, in presence of ultraviolet light, may form thymine dimers, causing kinks in the DNA molecule that inhibit normal function. Thymine could also be a target for actions of 5- fluorouracil (5-FU) in cancer treatment. In RNA, thymine is replaced with uracil in most cases. In DNA, thymine (T) binds to adenine (A) via two hydrogen bonds, thus stabilizing the nucleic acid structures. Thymine combined with deoxyribose creates the nucleoside deoxythymidine, which is synonymous with the term thymidine. A pair of abnormally chemically bonded adjacent thymine bases in DNA, resulting from damage by ultra-violet irradiation. The cellular processes that repair this lesion often make errors that create mutations. A B C D E F G H I J K L M N O P Q R S T U V W X Y Z.  Pyrimidine dimers are molecular lesions formed from thymine or cytosine bases in DNA via photochemical reactions. Ultraviolet light induces the formation of covalent linkages by reactions localized on the C=C double bonds. In dsRNA (double-stranded RNA), uracil dimers may also accumulate as a result of UV radiation. Two common UV products are cyclobutane pyrimidine dimers (CPDs, including thymine dimers) and 6,4 photoproducts. These premutagenic lesions alter the structure of DNA and consequently inhibit polymerases and arrest replication. A cyclobutane pyrimidine dimer (CPD) contains a four membered ring arising from the coupling of the C=C double bonds of pyrimidines. T^T dimers may be repaired by two mechanisms. (a) In photoreactivation repair, the PRE enzyme activated by blue light breaks the dimer, restoring the normal base pairing. Note that blue light can affect DNA because it is at the same end of the spectrum as UV radiation.  thymine dimer. Definitions: 1. a product of ultraviolet irradiation of thymine (free in ice or bound in nucleic acids) in which two thymine residues become linked by formation of a cyclobutane ring involving both C-5's and both C-6's at the expense of the two double bonds; several stereoisomeric forms are possible.  By Yolanda Smith, BPharm. Thymine, which is often abbreviated to T or Thy, can also be referred to as 5-methyluracil. It is one of the pyrimidine bases found in the nucleic acid of DNA, along with adenine, guanine and cytosine (A, G and C). These bases are the building blocks of DNA and life form on earth. As the name suggests, thymine may be derived by methylation of uracil at the 5th carbon. In RNA, thymine is replaced with uracil in most cases. In DNA, thymine (T) binds to adenine (A) via two hydrogen bonds, thus stabilizing the nucleic acid structures. Thymine combined with deoxyribose creates the nucleoside deoxythymidine, which is synonymous with the term thymidine. Thymine /ˈθaɪmɨn/ (T, Thy) is one of the four nucleobases in the nucleic acid of DNA that are represented by the letters G–C–A–T. The others are adenine, guanine, and cytosine. Thymine is also known as 5-methyluracil, a pyrimidine nucleobase. In RNA, thymine is replaced by the nucleobase uracil. In RNA, thymine is replaced with uracil in most cases. In DNA, thymine (T) binds to adenine (A) via two hydrogen bonds, thus stabilizing the nucleic acid structures. Thymine combined with deoxyribose creates the nucleoside deoxythymidine, which is synonymous with the term thymidine.
http://medical-dictionary.thefreedictionary.com/thymine+dimer http://www.news-medical.net/health/What-is-Thymine.aspx https://en.wikipedia.org/wiki/Thymine http://groups.molbiosci.northwestern.edu/holmgren/Glossary/Definitions/Def-T/thymine_dimer.html https://en.wikipedia.org/wiki/Thymine_dimer http://www.mun.ca/biology/scarr/Thymine_Dimer_Repair.html http://www.medilexicon.com/medicaldictionary.php?t=24937 http://www.news-medical.net/health/What-is-Thymine.aspx https://en.wikipedia.org/wiki/Thymine https://en.wikipedia.org/wiki/Thymine
what is thymine dimer