Saccharides – Simple Carbohydrates

00:01 Carbohydrates are molecules whose name literally means hydrates of carbon. As we'll see when I talk about the structural formulas for these, that literally is true. In this lecture, I'm going to discuss the nomenclature associated with carbohydrates, the structures that they have, the ways that they form ring structures, and chemical modifications that are done to them.

00:24 This slide shows a depiction of monosaccharides, that is, carbohydrates that contain only a single sugar within them. The general formula by which we can describe these is Cx(H2O)x, where x is a small integer. In the case of the sugar glucose for example, the structural formula is C6H12O6. We see this is also true for fructose and galactose. Ribose is a sugar that has five carbons andn its overall structure C5H10O5, glyceraldehyde C3H6O3. In each case we have hydrates of carbon.

01:04 Disaccharides are carbohydrates that contain two sugar molecules. So for example if we take glucose and we add fructose to it, we get the disaccharide known as sucrose.

01:15 If we take glucose and we add galactose to it, we get the sugar known as lactose. Or if we put two glucoses together, we get the sugar known as maltose.

01:26 Polysaccharides are carbohydrates that contain many, many sugars, and usually in the case of carbohydrates, the sugar that's in the polysaccharide is the same one throughout.

01:39 Polysaccharides include molecules such as cellulose, glycogen, amylose, amylopectin and chitin, and in each case, each of these polysaccharides is a polymer of the same repeating sugar unit.