Deoxyribonucleic acid thymine

The sugars are typically ribose (ribonucleic acids, RNA), or 2-deoxyribose (deoxyribonucleic acids, DNA). There are five common bases in nucleic acids adenine (A) thymine (T) uracil (U) cytosine (C) and guanine (G). DNA polymers incorporate the four bases. A, T, C, and G, and RNA, the set A, U, C, and G. 

Thymine was isolated from hydrolyzates of bovine thymus or spleen in 1893, several years before uracil, but it was not made synthetically until 1901. Unlike uracil, it comes not from ribonucleic but from deoxyribonucleic acids via thymidine (3-D-2 -deoxyribofuranosidothymine). 

As is well-known, nucleic acids consist of a polymeric chain of monotonously reiterating molecules of phosphoric acid and a sugar. In ribonucleic acid, the sugar component is represented by n-ribose, in deoxyribonucleic acid by D-2-deoxyribose. To this chain pyrimidine and purine derivatives are bound at the sugar moieties, these derivatives being conventionally, even if inaccurately, termed as pyrimidine and purine bases. The bases in question are uracil (in ribonucleic acids) or thymine (in deoxyribonucleic acids), cytosine, adenine, guanine, in some cases 5-methylcytosine and 5-hydroxymethylcyto-sine. In addition to these, a number of the so-called odd bases occurring in small amounts in some ribonucleic acid fractions have been isolated. 

Like RNAs (see p.82), deoxyribonucleic acids (DNAs) are polymeric molecules consisting of nucleotide building blocks. Instead of ribose, however, DNA contains 2 -deoxyribose, and the uracil base in RNA is replaced by thymine. The spatial structure of the two molecules also differs (see p.86). 

DNA, short for deoxyribonucleic acid, is the coding machinery of life. The beauty of DNA is in its simplicity that results in the complexity of life. The double helix of DNA is made of the chemicals adenine (A), guanine (G), thymine (T), and cytosine (C). These chemical are bound in long stretches as AT and CG pairs,... 

DNA (deoxyribonucleic acid)—Carrier of genetic material that determines inheritance of traits. DNA is in chromosomes in every cell of the body except red blood cells and is copied when cells divide. DNA molecules are shaped like a double helix, and are composed of sequences of four bases adenosine (A), cytosine (C), guanine (G), and thymine (T). The sequence of the bases directs production of particular proteins by determining the sequence of amino acids in proteins. The double-helk structure of DNA helps it transmit genetic information. 

The most important pyrimidine derivatives are those upon which biological organisms depend. Cytosine 1018 and uracil 1019 are found in ribonucleic acid (RNA) in the form of their ribonucleotides, cytidine 1020 and uridine 1021, while in deoxyribonucleic acid (DNA), cytosine and thymine 1022 are found in the form of their 2 -deoxyribonucleotides, 2 -deoxycytidine 1023 and thymidine 1024. 5-Methylcytosine 1025 is also found to a small extent (c. 5%) in human DNA in the form of its 2 -deoxyriboside 1026, and 5-(hydroxymethyl)cytosine-2 -deoxyriboside 1027 has also been detected in smaller amounts <2005CBI1>. Many variants of cytosine and uracil can be found in RNA including orotic acid 1028 in the form of its ribonucleotide orotidine 1029. Other pyrimidine derivatives to have been isolated from various biological sources include 2 -deoxyuridine 1030, alloxan 1031, and toxopyrimidine (pyramine) 1032 (Figure 2). 

Nucleic Acid. A nucleic acid is a natural polynucleotide. It is a sugar-phosphate chain with purine and pyrimidine bases attached to it, as shown in Chart 10. If the sugar is deoxyribose and the pyrimidine bases are cytosine and thymine, the nucleic acid is deoxyribonucleic acid, DNA if the sugar is ribose, and the pyrimidine bases are (mostly) cytosine and uracil, the nucleic acid is ribonucleic acid, RNA. The sequence of bases may appear arbitrary and random, but it constitutes a meaningful code (see Code Word). In double-stranded nucleic acids,... 

Density of states weighted Franck-Condon factor Deoxyribonucleic acid Barrier height for the adiabatic hole motion Difference in ionization potentials of adenine-thymine and guanine-cytosine base pairs... 

The pyrimidines found in the deoxyribonucleic acids are thymine and cytosine, and the purines are adenine and guanine. Their structures have been discussed in Section 8-8. 

Pyrimidine natural products are particularly important (Scheme lb). The nucleic acids contain pyrimidine and purine bases ribonucleic acids (RNA) contain D-ribose and uracil, deoxyribonucleic acids (DNA) contain 2-deoxy-D-ribose and thymine and both types contain phosphate residues,... 

Cullis PM, McClymont JD, Malone ME, Mather AN, Podmore ID, Sweeney MC, Symons MCR (1992) Effects of ionizing radiation on deoxyribonucleic acid. Part 7. Electron capture at cytosine and thymine. J Chem Soc Perkin Trans 2 1695-1702... 

Of these pyrimidines, uracil and cytosine are constituents of ribonucleic acid, whereas thymine and cytosine are components of deoxyribonucleic acid. It was generally accepted that these nitrogenous heterocycles were the only pyrimidine components of the nucleic acids. The possibility that the nucleic acids might contain moieties other than those described had been voiced by Gulland,26 Chargaff and Vischer,27 and Davidson.28 The... 

Thymine and 5-methylcytosine, at first found only as components of deoxyribonucleic acid, have since been discovered in the ribonucleic acid fraction derived from certain microorganisms.42,43 [Uracil, on the other hand, previously demonstrated as a constituent of ribonucleic acid only, has been obtained, as a deoxynucleoside, from an enzymic hydrolyzate of a commercial sample of herring-sperm deoxyribonucleic acid.44 However, this... 

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