Bio 111 2/2/09 Functional Groups Part of a larger more complex molecule & have particular reactive characteristics (Table 3.1 Page 43) Isomers Same formula, but different structures Structural ? same atoms, different bonding relationships Stereo isomer ? same bonding relationships, but different special positions Geometric ? cis (same side) and trans (opposite sides) Enantiomers ? pair of molecules that are mirror images of each other Biological macromolecules Polymers of small similar chemical subunits Formed by linking subunits together Dehydration synthesis (requires energy input) Broken down into subunits Hydrolysis (requires energy output) Carbohydrates: C:H:O, usually in a ratio of 1:2:1 Function ? primarily as energy storage Monosaccharides: Glucose is the most important (C6H12O6) Hydroxyl group attached to each C, except 1, double bonded O (carboxyl group) C-skeleton 3-10 Carbons. 5C = pentose, 6C = hexose Form rings in aqueous solutions Two forms (anomers) ? = hydroxyl group on C-1; below the plane ? = hydroxyl group on C-1; above the plane D glucose is biologically active, L is not (it is unable to be metabolized) Disaccharides: double sugars ? play a role in sugar transport 2 monosaccharides joined by a glycosidic bond Sucrose Lactose Maltose Polysaccharides: Hundreds to thousands of monosaccharides Storage polysaccharides Starch ? glucose monomers: 1-4 linkages simplest form in mylose (unbranched) 1-6 linkages form branches Sugar storage in plants Glycogen Sugar storage in animals Store in liver and muscle Has more 1-6 linkages than starch does Structural polysaccharides Cellulose ? glucose monomers. Parallel strands held together by H bonds Few organisms can digest cellulose (bacteria in guts of cattle, termites) Chitin One of the most abundant substances on earth Modified cellulose Exoskeletons of arthropods, fungi, cell walls ? 1-4 linkages Monomers of glucose derivative called N acetylglucosomine (NAC) Peptidoglycan Cell walls of bacteria ? 1-4 linkages Short chains of amino acids attached to sugar groups Lipids: Chemically diverse, no subunits join to make polymers Non polar covalent bonds hydrophobic Fats = solid at room temperature Oils = liquid at room temperature Triglycerides are made up of 3 fatty acids and 1 glycerol
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