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Discuss the following with your group and be prepared to discuss with the class 1. Why is the shape of a molecule important? 2. How is a covalent bond different from ionic? 3. How are hydrogen bonds different from covalent? We are beginning our first Unit today: Bio-Molecules Right now, the test is set for Tuesday, Sept 17th AP Biology Functional groups -parts of organic molecules that are involved in chemical reactions They give organic molecules distinctive properties hydroxyl amino carbonyl (ketones and aldehydes) sulfhydryl carboxyl phosphate Polymers - long molecules built by linking repeating building blocks in a chain monomers building blocks repeated small units covalent bonds H 2O HO H HO HO H H How to build a larger Bio-molecule Dehydration Synthesis (also called Condensation Reaction) joins monomers by “taking” H2O out one monomer donates OH– other monomer donates H+ together these form H2O requires energy & enzymes HO H 2O H HO H enzyme This is an example of an Anabolic, endergonic reaction. HO H How to break down a larger molecule Hydrolysis (also called Digestion) use H2O to breakdown polymers reverse of dehydration synthesis takes off one monomer at a time H2O is split into H+ and OH– H+ & OH– attach to ends requires enzymes releases energy H2O This is an example of an Catabolic, exergonic reaction. HO HO enzyme H HO H H Bio-Molecules Large organic molecules formed by smaller molecules bonding together macromolecules 4 major classes of macromolecules: carbohydrates lipids proteins nucleic acids Proteins Multipurpose molecules AP Biology 2008-2009 Proteins - Most structurally & functionally diverse group Various functions: enzymes (speed up metabolism) structure physical stability and movement (keratin-hair/nails/skin, collagenbones/cartilage/tendons, myosin-muscles) transport (hemoglobin- in red blood cells, proteins in cell membranes) cell communication/regulatory signals (insulin & other hormones) receptors defense (antibodies/recognize foreign invaders) storage (hold amino acids for later use) Amino acids Protein monomer (building block) central carbon Two functional groups: carboxyl group (acid) amino group H O H | || —C— C—OH —N— | H R R group (side chain) variable group that is different for each amino acid gives unique chemical properties to each amino acid like 20 different letters of an alphabet can make many words (proteins) Peptide Bonds – Linking of Amino Acids Effect of different R groups: Nonpolar amino acids nonpolar & hydrophobic Effect of different R groups: Polar amino acids polar or charged & hydrophilic Building proteins Peptide bonds covalent bond between NH2 (amino) of one amino acid & COOH (carboxyl) of another C–N bond H2O dehydration synthesis peptide bond Building proteins Polypeptide chains have direction N-terminus = NH2 end C-terminus = COOH end repeated sequence (N-C-C) is the polypeptide backbone Protein structure & function Function depends on structure 3-D structure twisted, folded, coiled into unique shape pepsin hemoglobin collagen Primary (1°) structure Order of amino acids in chain amino acid sequence determined by genes (DNA) slight change in amino acid sequence can affect protein’s structure & its function even just one amino acid change can make all the difference! (Example of structure determining function) Sickle Cell Anemia What type of mutation is this? Secondary (2°) structure “Local folding” folding along short sections of polypeptide interactions between adjacent amino acids H bonds weak bonds between R groups forms sections of 3-D structure helix pleated sheet Tertiary (3°) structure “Whole molecule folding” interactions between distant amino acids and R groups Quaternary (4°) structure More than one polypeptide chain bonded together collagen = skin & tendons hemoglobin Protein denaturation Unfolding a protein conditions that disrupt H bonds and ionic bonds temperature pH salinity alter 2° & 3° structure alter 3-D shape destroys functionality some proteins can return to their functional shape after being denatured, many cannot Enzymes a type of protein that acts as a catalyst, speeding up chemical reactions Substrate (sucrose) Glucose H 2O Fructose Some enzymes require other atoms or molecules in order to function: -Cofactors: inorganic ions, such as iron, copper, or zinc that bind to enzymes in order to help break down specific substances. -Coenzymes: organic molecules that are required by certain enzymes to carry out catabolic reactions.