Structure and Function of the Genetic Material
Chromosomes are cellular structures made up of genes that carry hereditary information. Genetics is the study of how genes carry information, how they are replicated and passed to other generations, and how they affect the characteristics of an organism. A gene is a segment of DNA that codes for a functional product. The genetic information in a cell is the genome. In Chapter 2 we saw that DNA is composed of repeating nucleotides containing the bases adenine (A), thymine (T), cytosine (C), or guanine (G); a deoxyribose sugar; and a phosphate group. Bases occur in specific complementary base pairs, the hydrogen bonds from which connect strands of DNA: adenine with thymine, and cytosine with guanine. The information in DNA can be transcribed into RNA (transcription) and this information, in turn, translated into protein (translation).