Proteins - . The carboxyl or amino group may ionize...

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Proteins Importance of proteins Some important functions of proteins are listed below. enzymes (chemical reactions) hormones storage (egg whites of birds, reptiles; seeds) transport (hemoglobin) contractile (muscle) protective (antibodies) membrane proteins (receptors, membrane transport, antigens) structural toxins (botulism, diphtheria) Enzymes Enzymes are proteins that speed up the rate of chemical reactions. Example: The presence of an enzyme in the chemical reaction diagrammed below causes hypothetical chemicals A and B to react, producing C. Proteins are able to function as enzymes due to their shape. For example, enzyme molecules are shaped like the reactants, allowing the reactants to bind closely with the enzyme. Amino Acids Amino acids are the building blocks of proteins. Twenty of the amino acids are used to make protein. Each has a carboxyl group (COOH) and an amino group (NH 2 ). Each amino acid is different and therefore has its own unique properties. Some amino acids are hydrophobic, others hydrophilic
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Unformatted text preview: . The carboxyl or amino group may ionize (forming NH 3 + or COO-). The "R" group of some amino acids is nonpolar and the "R" group of some others is polar or it ionizes. Amino acids are joined together by a peptide bond . It is formed as a result of a condensation reaction between the amino group of one amino acid and the carboxyl group of another. Polypeptides Two or more amino acids bonded together are called a peptide . A chain of many amino acids is referred to as a polypeptide . The complete product, either one or more chains of amino acids, is called a protein . There is unequal sharing of electrons in a peptide bond. The O and the N are negative and the H is positive. Levels of structure The large number of charged atoms in a polypeptide chain facilitates hydrogen bonding within the molecule, causing it to fold into a specific 3-dimensional shape. The 3-dimensional shape is important in the activity of a protein....
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This note was uploaded on 11/10/2011 for the course CHEM ch 101 taught by Professor - during the Fall '10 term at Montgomery.

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Proteins - . The carboxyl or amino group may ionize...

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