Enzymatic Breakdown Of Food

Enzymatic Breakdown Of Food - Lab Exercise Enzymatic...

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Lab Exercise Enzymatic Breakdown of Food Adopted from Mr. Bob Nabors, Professor of Biology, retired, TCC, South Campus Introduction Food must be broken down into substances that the body can absorb and use. Digestive enzymes are proteins which speed up chemical digestion. Each enzyme has a set of optimal conditions of temperature and pH under which it performs best. A particular enzyme is very specific about the substrate with which it will bind. For example, maltose, a disaccharide sugar can bind with the enzyme maltase, but not sucrase. There are three major classes of digestive enzymes based on the types of food they affect. A series of carbohydrases act on complex carbohydrates to convert them to simple sugars (monosaccharides). For example, salivary amylase in the mouth breaks starches which are large polysaccharides into smaller ones. If food stays in the mouth long enough, this enzyme can break the polysaccharides all the way down to maltose, a disaccharide. Once the food is in the stomach, the acid soon stops the action of amylase, and carbohydrate digestion doesn’t start again until the food reaches the duodenum, where pancreatic bicarbonate ions neutralize the acid, and pancreatic amylase continues the digestive process. Here the complex carbohydrates become maltose. From intestinal glands, three enzymes – maltase, sucrase, lactase – complete the conversion of all digestible carbohydrates to the monosaccharides – glucose, fructose and galactose. Maltose becomes two glucose molecules. Sucrase action changes sucrose to glucose and fructose. Lactase action results in one glucose and one galactose from lactose. The small intestine absorbs these monosaccharides, and they are transported to the liver via the hepatic portal system. The liver stores much of the sugar as glycogen but some of it goes throughout the body as a source of fuel. If excess sugar is available, it is converted to fat. Proteases act upon proteins to release amino acids
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This note was uploaded on 04/23/2008 for the course SCI 1406 taught by Professor Sheffield during the Spring '08 term at Tarrant County.

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Enzymatic Breakdown Of Food - Lab Exercise Enzymatic...

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