Lecture _3 - Amino Acids and Proteins

Lecture_3 Amino - The Structure and Function of Large Large Biological Molecules Lecture#3 Amino Acids and Proteins Campbell Reece 8th Edition

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The Structure and Function of arge Biological Molecules Large Biological Molecules Lecture #3 – Amino Acids and Proteins Campbell Reece, 8th Edition Reading Assignment: Chapters 5 BIOL 203 – Spring 2010 Ralph Feuer
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Functional Groups Here “R” represents the rest of the molecule H H QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture. CC H HH OH QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture. C C C O H H H H QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture. C C H H H OH O Ethanol Acetone H H H Acetic Acid Organic compounds can contain atoms other than C and H Form “Functional Groups” Characterized by the types of atoms present and the way they are bonded Giving these groups special properties Bonds between C and O or N - polar covalent bonds Can form Hydrogen Bonds.
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Linking Functional Groups To Polymers Organic molecules with certain functional groups can be joined by a covalent bond formed when a molecule of water is removed Allows the creation of new types of organic molecules An ester is formed by combining An amide is formed by combining an alcohol and a carboxylic acid. an amine and a carboxylic acid . O O R-OH + HO-P-OH O - R-O-P-OH + H 2 O O - •A phosphoester is formed from an alcohol and phosphoric acid. •More than one phosphoester bond can be formed in this way linking two molecules together
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Ester Bonds Link Fatty Acid Carboxyl Groups To OH- Groups Of Glycerol Fat droplets (stained red)
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utline Outline α -Amino Acids: Carboxyl and amino groups bonded to α -carbon Acid/Base properties Carboxyl group is proton donor Î weak acid Polypeptides and Proteins Peptide Bond join amino group of one amino acid with carboxyl roup of another by forming and amide bond yg p p Amino group is proton acceptor Î weak base At physiological pH: H 3 N+-Ca-COO- Alpha carbon is tetrahedral and bonded to 4 different groups L configuration for all natural amino acids (few xceptions) group of another by forming and amide between them Î Peptide Bond C-N bond has partial double bond character Peptides and Polypeptides Peptides contain relatively few amino acids linked by peptide bonds: dipeptide, tripeptide, trapeptide exceptions) 20 different R groups Classification based on R-group - know one example from each Aliphatic-hydrophobic Aromatic-hydrophobic tetrapeptide, …. Polypeptide contains many amino acids and if there are very many amino acids one can call it protein Proteins have molecular weights > several thousand and have 3-4 levels of structure Polar Uncharged-hydrophilic Acidic-hydrophilic Basic-hydrophilic Primary Structure (1°) sequence of amino acids connected by peptide bonds Secondary Structure (2°) local conformation of peptide bond backbone stabilized by H- bonds: a-helix: intrachain H-bonds & b- sheet: interchain H-bonds Tertiary Structure (3°): The complete 3-
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This note was uploaded on 03/07/2010 for the course BIO 203 taught by Professor Feuer during the Spring '10 term at San Diego State.

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Lecture_3 Amino - The Structure and Function of Large Large Biological Molecules Lecture#3 Amino Acids and Proteins Campbell Reece 8th Edition

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