Collegeboardcom ap biology 2008 scoring guidelines

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Unformatted text preview: AP® BIOLOGY 2008 SCORING GUIDELINES Question 1 1. The physical structure of a protein often reflects and affects its function. (a) Describe THREE types of chemical bonds/interactions found in proteins. For each type, describe its role in determining protein structure. (6 points; 1 point for bond/interaction description, 1 point for description of role) Bond/interaction Covalent/ peptide Disulfide/ covalent Hydrogen van der Waals Hydrophobic Ionic Description sharing electrons OR linking amino acids together disulfide, S–S bond (bridges); sulfur-containing R group bonding H–O or H–N interactions unequal electron clouds in R group; dipole moments nonpolar R groups charged R groups Role associated to bond/interaction amino acid sequence OR primary structure (no credit for chain or polypeptide alone) tertiary or quaternary structure α helix, β sheet; secondary, tertiary, or quaternary structure tertiary or quaternary structure tertiary or quaternary structure tertiary or quaternary structure (b) Discuss how the structure of a protein affects the function of TWO of the following. (3 points maximum) Muscle contraction (1 point for each bullet; 2 points maximum) • Actin (thin filaments) and myosin; cross-bridges OR filamentous proteins slide past each other. • Troponin/tropomyosin interaction blocks binding of myosin to actin. • Ca2+ changes troponin shape/binding of troponin-tropomyosin to actin altered. • ATP/ADP changes myosin structure. Regulation of enzyme activity (2 points maximum) • Shape change caused by (1 point for each bullet) o Binding of a...
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This note was uploaded on 11/23/2009 for the course BIOLOGY 1101 taught by Professor Keith during the Winter '05 term at The University of Oklahoma.

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