A genome contains the genetic material that is passed from parent to offspring. The genome embodies the "genetic blueprint" that determines or influences various characteristics, such as height, seed yield, grazing tolerance, and other characteristics of an individual plant. The nuclear genome is packaged in chromosomes found in the nucleus of the cell. Chromosomes contain deoxyribonucleic acid, better known as DNA, which is composed, in part, of the nucleotide-forming bases adenine (A), thymine (T), guanine (G), and cytosine (C). The arrangement (i.e., sequence) of these bases on the DNA molecule determines which enzymes the plant produces; in turn, these enzymes provide the biochemical basis for the expression of traits by the plant. Thus, variation in DNA sequence can lead to trait differences passed on to offspring (see Chapter 19).