Part I
The molecule that is the basis for heredity, DNA, contains the patterns for constructing proteins in the body, including the various enzymes. A new understanding of heredity and hereditary disease was possible once it was determined that DNA consists of two chains twisted around each other, or double helixes, of alternating phosphate and sugar groups and that the two chains are held together by hydrogen bonds between pairs of organic bases adenine (A) with thymine (T) and guanine (G) with cytosine (C).
