Chapter 9 - Cellular metabolism

Abstract

Metabolism refers to the sum of all chemical reactions within the body and is subdivided into catabolism and anabolism. These two types of chemical reactions are coupled to one another. Metabolic processes occur constantly and are essential in maintaining normal functions within the body. This chapter defines metabolism and its two aspects, and discusses the role of adenosine triphosphate (ATP) in metabolism. It compares oxidation and reduction reactions. The role of nicotinamide adenine dinucleotide (NAD) and flavin adenine dinucleotide (FAD) in oxidation-reduction reactions is explained. The chapter identifies the hormones that are important in altering metabolism and how they bring about any changes. It then describes how dietary carbohydrates are digested and absorbed. Glycolysis is defined, along with the location in the cell where it occurs, and the net yield of this reaction. The cause for the conversion of glucose to lactic acid is explained. A summary of the metabolism of glucose within the mitochondrion, including the net yield of products, is provided. The chapter goes on to identify the part of the aerobic pathway where oxygen is utilized and how, and compares aerobic and anaerobic reactions. The terms gluconeogenesis, glycogenesis, and glycogenolysis are defined, as are essential and nonessential amino acids. The chapter describes how proteins can be used as energy sources. The significance of deamination and transamination is considered. Finally, the location and significance of the urea cycle are discussed.