NS exam 2 review guide - NS 132 Exam#2 Review Outline...

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NS 132 Exam #2 Review Outline Protein Composition and Structure Proteins are chains of ____amino acids_____________________________. Amino acids are the "building blocks" of proteins; each block is joined together by a peptide bond. Proteins can be made up of hundreds or thousands of amino acids; small proteins are called "peptides" or "polypeptides" (a peptide is a protein). Proteins can be enzymes, hormones, transporters, antibodies, carriers, cellular pumps, and receptors (and other things), and they form part of many structures (bone, teeth, etc). There are ____20 _____ different amino acids and about 100,000 different proteins in the human body. 9 amino acids are essential or indispensable. This means they must be obtained from the diet. Amino acids are composed of carbon, hydrogen, oxygen, and ____nitrogen _____(and sometimes sulfur). It is nitrogen that distinguishes protein from the other macronutrients. The body is constantly synthesizing and breaking down proteins to carry out the many functions required. The sequence for proteins is carried in DNA; DNA tells the body how to make the proteins it needs. One gene carries the "code" for one protein. A protein's amino acid sequence determines its properties . A protein's shape (e.g., whether it's coiled or folded, how it's coiled or folded) determines its function. Protein Digestion and Absorption Proteins cannot be absorbed whole; they are broken down by enzymes into amino acids and dipeptides . Proteins are denatured; this exposes certain sections of the protein, making them available for interaction. Denaturation occurs during digestion by acids in the stomach and small intestine (protein denaturation can also occur by heat - as in cooking - and by alcohol, bases, and the salts of heavy metals). In the stomach : Acid and protease begin to denature proteins. In the small intestine : Proteases continue to denature proteins until they are reduced to the absorbable units. REVIEW THE TEXT for a succinct summary of the fate of an amino acid in digestion. Protein Functions Protein's main function in our diets is to provide us with the essential amino acids we CAN'T make and to provide a source of nitrogen for the amino acids the body can make. Each cell in the body has an amino acid "pool" with amino acids supplied both by the diet and by the body's own production. List of protein functions: 1. Body constituents: Blood clotting factors Blood transport proteins (e.g., iron, hemoglobin) Lipoproteins Structural components (e.g., muscle, bone matrix, cell membranes, connective tissue) 2. Maintain fluid balance by attracting and retaining fluid in the blood via osmosis. 3.
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This note was uploaded on 03/30/2008 for the course NUTRI SCI 132 taught by Professor Anderson during the Spring '08 term at University of Wisconsin.

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NS exam 2 review guide - NS 132 Exam#2 Review Outline...

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