biolgoy chapter 5 II

biolgoy chapter 5 II - Jamie Cohen Chapter 5 77-91 Chapter...

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Jamie Cohen Chapter 5: 77-91 Chapter 16: 308-310 5.4 Proteins Have Many Structures, Resulting in a Wide Range of Functions -Enzymes are catalysts (chemical agents that selectively speed up chemical reactions without being consumed by the reaction) -Enzymatic: selective acceleration of chemical reactions -Structural: support -Storage: storage of amino acids -Transport: transport of other substances -Hormonal: coordination of an organism’s activities -receptor: response of cell to chemical stimuli -contractile/motor: movement -defensive: protection against disease -Polypeptides: polymers of amino acids (protein: 1 or more polymers, each folded and coiled into a specific 3-D structure -Amino Acids: organic molecules with a carboxyl group and an amino group -center: alpha carbon (asymmetric) H R O N C C H H OH Amino Carboxyl -physical/chemical properties of side chain (radical group) determine unique characteristics of an amino acid Amino Acids QuickTime X and a decompressor are needed to see this picture. -Peptide bond: covalent bond between 2 amino acids through dehydration
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synthesis QuickTime and a decompressor are needed to see this picture. -4 Levels of structure 1) Primary: unique sequence of amino acids 2) Secondary: result of hydrogen bonds between repeating constituents of polypeptide backbone -alpha helix: delicate coil held together by H boding between every forth amino acid -beta pleated sheet: h bonds connects between parts of the 2 parallel polypeptide backbones 3) Tertiary: interactions from radical groups -hydrophobic interaction: hydrophobic side chains usually end up in clusters at the core of the protein -disulfide bridges: form where 2 cysteine monomers with sulfhydryl groups (-SH) on their side chains are brought close together by the folding of the protein -S of one cysteine bonds to the sulfur of the 2 nd and the disulfide bridge rivets part of the protein together 4) Quaternary -2 more polypeptide chais aggregate into one functional molecule Sickle Cell Disease -substitution of valine for glutamoic acid (normal one) -abnormal red blood cells …not disk-shaped but tend to crystallize into a sickle shape -angular cells clog tiny blood vessels impeding blood flow
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What Determines Protein Structure? -pH, salt concentration, temperature, and other aspects are altered, the protein may denature (unravel and lose its native shape -most denature if they are transferred from an aqueous environment to an organic solvent-the polypeptide refolds so that its hydrophobic regions face outward toward the solvent -denaturation also from excessive heat
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biolgoy chapter 5 II - Jamie Cohen Chapter 5 77-91 Chapter...

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