Book excerpt: The functional properties of any molecule are directly related to, and affected by, its structure. This is especially true for DNA, the molecular that carries the code for all life on earth. The third edition of Understanding DNA has been entirely revised and updated, and expanded to cover new advances in our understanding. It explains, step by step, how DNA forms specific structures, the nature of these structures and how they fundamentally affect the biological processes of transcription and replication. Written in a clear, concise and lively fashion, Understanding DNA is essential reading for all molecular biology, biochemistry and genetics students, to newcomers to the field from other areas such as chemistry or physics, and even for seasoned researchers, who really want to understand DNA. - Describes the basic units of DNA and how these form the double helix, and the various types of DNA double helix - Outlines the methods used to study DNA structure - Contains over 130 illustrations, some in full color, as well as exercises and further readings to stimulate student comprehension