DNA bases
DNA is a helix of two paired complementary strands, each composed of an ordered string of Nucleotides. A nucleotide is attached to one of the chemically constituents called bases attached to a phosphorylated molecule of the 5-carbon sugar deoxyribose (is also a constituent of a nucleotide).
These four bases in the DNA are:
Watson- Crick base pairing is between adenine and thymine and between cytosine and guanine in the complementary strands which holds the strands together. The base pairs are held together by hydrogen bonds in-between. Adenine (A) and Guanine (G) are called purines as they both have double-ring structure. Whereas, thymine (T) and cytosine (C) are called pyrimidines as they both have a single-ring structure. Due to the different structure of the bases, when A binds to T there will be two hydrogen bonds between the bases and when C binds to G there will be three hydrogen bonds between the bases. [2]
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