Thymine, pairing with adenine

The two strands which make up DNA are held together by hydrogen bonds between complementary pairs of bases adenine paired with thymine and guanine paired with cytosine. The integrity of the genetic code (and of life as we know it) depends on error-free transmission of base-pairing information. 

One way in which chemical compounds can induce base substitution mutation is through their incorporation into the structure of DNA itself. Thus, 5-bromodeoxyuridine (or bromouracil) can replace thymidine in DNA, where it serves as an efficient mutagenic agent.767 2-Aminopurine, an analog of adenine, pairs with thymine, just as does adenine when incorporated into DNA. 

Figure 1.3. Watson-Crick Base Pairs. Adenine pairs with thymine (A-T), and guanine with cytosine (G-C). The dashed lines represent hydrogen bonds.

In DNA, two antiparallel polynucleotide chains are joined by pairing between their bases and are twisted to form a double helix. Adenine pairs with thymine, and guanine pairs with cytosine. One chain runs in a 5 to 3 direction and the other runs 3 to 5. ... 

The most stable DNA stracture is formed when two polynucleotide chains are joined by hydrogen bonding between the side chain bases. The base pairing is specific in that adenine pairs with thymine and guanine pairs with cytosine (A-T G-C)... 

Purines are bases found in the nucleosides and nucleotides that make up nucleic acids. In nucleic acids, the purines match up with specific pyrimidine bases. The matching between purines and pyrimidines forms "base-pairs" in which adenine pairs with thymine (in DNA) or uracil (in RNA). Guanine pairs with the base cytosine in either nucleic acid. 

DNA Structure. Genetic information is encoded by the sequence of different nucleotide bases in DNA. DNA is double-stranded it contains two antiparallel polynucleotide strands The two strands are joined by hydrogen bonding between their bases to form base-pairs Adenine pairs with thymine, and guanine pairs with cytosine The two DNA strands run in opposite directions. One strand runs 5 to 3, and the other strand runs 3 to 5. The two DNA strands wind around each other, forming a double helix... 

The X-ray diffraction pattern of DNA demonstrated the helical structure and the diameter. The combination of evidence from X-ray diffraction and chemical analysis led to the conclusion that the base pairing is complementary, meaning that adenine pairs with thymine and that guanine pairs with cytosine. Because complementary base pairing occurs along the entire double helix, the two chains are also referred to as complementary strands. By 1953, studies of the base composition of DNA from many species had already shown that, to within experimental... 

---