This text is designed for the two-semester introductory biochemistry course but could be customized for a one semester course as well. Biochemistry is the application of chemistry to the study of biological processes at the cellular and molecular level. It emerged as a distinct discipline around the beginning of the 20th century when scientists combined chemistry, physiology and biology to investigate the chemistry of living systems. Biochemistry is both a life science and a chemical science - it explores the chemistry of living organisms and the molecular basis for the changes occurring in living cells. It uses the methods of chemistry, physics, molecular biology and immunology to study the structure and behaviour of the complex molecules found in biological material and the ways these molecules interact to form cells, tissues and whole organisms. The chapter organization generally follows the traditionally used biochemistry texts to allow easier adoption by faculty and use by students.