Biochemistry

The molecular content in purine DNA is equal to the content of pyrimidines, i. e., the adenine content is equal to the content of thymine (A = T or A / T = 1), the guanine content is equal to the cytosine content (G = C or G / C = 1), the total content of adenine and guanine is equal to the total content of cytosine and thymine (A + G) = (С + T) or (A + T) / (С + T) = 1. In addition, it was found that the number of amino groups (6) that make up the DNA of purine bases (adenine and guanine) is equal to the number of amino groups (6) that make up the pyrimidine bases (cytosine and thymine) (Fig. 5 .2 ). Two hydrogen bonds are formed between adenine and thymine, and three are formed between guanine and cytosine. Thymine Cytosine Figure 5.2 - Bases complementarity in DNA 119