PROTEINS - PROTEINS Proteins like carbohydrates provide 4 K...

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PROTEINS Proteins like carbohydrates provide 4 K calories per gram. Unlike carbohydrates their role in the body is not primarily as a source of or storage form of energy. Proteins perform a number of key functions in the body. These include Functions of Proteins Enzymes - Some proteins are enzymes. These are biological catalysts. They speed up chemical reactions. Examples would include the digestive enzymes trypsin and pepsin Storage - Some proteins are used for storage. Ovalbumin is a storage form of proteins in eggs. Ferritin is a molecule found in the liver with iron attached to it. It is the way the body stores iron for future use. Transport - Some proteins are used to transport substances through the blood stream. All cells in your body require oxygen. Oxygen is a gas and it cannot be bubbled through the blood. Hemoglobin is a protein that is designed to transport oxygen. Similarly β-lipoproteins are used to transport fatty acids and cholesterol. These molecules are not soluble in water but can be carried attached to a protein. Contractile - Some proteins function in contraction and make motion possible. Examples are actin and myosin. They are the two main proteins in muscle. Other contractile proteins allow motion within each cell. Protective - Proteins can serve to protect. Antibodies are made to destroy foreign invades while thrombin is used to form blood clots and to stop bleeding. Hormones - Some hormones like insulin and growth hormone are really very small proteins. Structural - Proteins can serve as structural entities. Keratin is the main protein in hair, collagen is used to make connective tissue and elastin provides flexibility to skin. Proteins are polymers of amino acids Proteins must be broken down (hydrolyzed) to amino acids before they can be utilized. Once absorbed amino acids are utilized to make proteins or are converted to energy. About 20% of the human body is made of protein.
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Proteins are composed of amino acids Contain an amino group ( -NH 2 ) and an acid group ( - COOH ). There are twenty amino acids that are found in proteins. Peptide Bond A bond formed by the condensation of the amino group ( -NH 2 ) of one amino acid with the acid group (-COOH ) of another amino acid resulting in the loss of water. These bonds are not easily broken. Cooking would not normally result in their breakage. Condensation - Hydrolysis Removal of water (H 2 O) and formation of a bond is called condensation. This occurs in the formation of a number of polymers The reversal of this is hydrolysis that involves the addition of water to a bond, with the result that the bond is broken. You should know the difference.
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This note was uploaded on 06/22/2011 for the course FDSCTE 201 taught by Professor Magino during the Spring '11 term at Ohio State.

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PROTEINS - PROTEINS Proteins like carbohydrates provide 4 K...

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