Minimizes ph fluctuations binds or releases h oh ions

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Minimizes pH fluctuations; binds or releases H+ & OH- ions depending on conditions thus protecting organisms & their cells q Blood – H2CO3 & HCO3- ions; neutralizes H+ rise during exercise, OH- rise during hyperventilation q Excess H+ ions bind HCO3-; excess OH- ions neutralized by protons q Blood stays at pH 7.4 q pH of fluid within cell regulated by phosphate buffer system (H2PO4- & HPO4-2)
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9/1/17 4 Amphoteric Molecule q a molecule that can serve as both an acid & a base q usually both a positive & negative charge q examples: water and amino acids. H 3 O H H 2 O OH + H Acid Base Amphoteric Molecule Biomolecules q Biological molecules or biochemicals q Often contains carbon (organic molecules) q Often contains “functional groups” linked by: q Ester bonds – between carboxylic acids and alcohols q Amide bonds - between carboxylic acids and amines Types of Biomolecules q Macromolecules q Structural and functional units of the cell’s organelles. q Highly organized molecules q Polymers (composed of monomers) q Proteins, nucleic acids, polysaccharides, lipids q Low-molecular-weight precursors q Building blocks of macromolecules q Sugars, amino acids, nucleotides, fatty acids q Metabolites q Metabolic intermediates q Synthesized inside the cell thru a metabolic pathway (a series of chemical reactions starting with a specific material). q Molecules of miscellaneous function q Vitamins, steroids, hormones, ATP, cyclic AMP, urea Formation and Breakdown of Macromolecules Types of Macromolecules Carbohydrates q With sugars as building blocks q Deposits of chemical energy q Durable building material for cell parts. q With a general formula of (CH 2 O) n q Glycosidic bonds (covalent bonds) > energy source q Types: q Monosaccharides (glucose, fructose) q Trioses – 3 carbons q Tetroses – 4 carbons q Pentoses – 5 carbons q Hexoses – 6 carbons q Heptoses – 7 carbons q Disaccharides (sucrose, lactose) q Oligosaccharides (forms glycolipids, glycoproteins) q Polysaccharides (cellulose, chitin)
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9/1/17 5 Monosaccharides q Backbones of carbon atoms linked by single bonds q Each carbon linked to hydroxyl group (except for one linked to carbonyl group, C=O) Keto hexose (ketose) Aldo hexose (aldose) Pyranose Ring Planar Ring 3D Structure Ball and Socket Structure Stereoisomers q Enantiomers (mirror image) q Carbon acting as site of stereoisomerism is called “assymetric carbon” q Affects the structure of biological molecules OH - right OH - left OH - up OH - below Polysaccharides Polysaccharides q Glycogen q Animal starch (surplus chemical energy q Glucose polymer joined by 1-4 glycosidic bonds (others 1-6) q Molecular weight ranges from 1-4 million Daltons q Starch q Plant polysaccharide (cereals, potatoes) q Polymer of amylose and amylopectin q Cellulose q Structural material (cotton, linen) q Long unbranched polymers q Most abundant organic material on earth q Chitin q Polymer of N-acetylglucosamine (acetyl amino group, HNCOCH 3 ) q Shells of invertebrates (crustaceans, insects) q Glycosaminoglycans (CAGs) q Complex structures q Found in spaces surrounding cells Lipids q Non-polar biomolecules q Inability to dissolve in water q Ability to dissolve in organic solvents q Fats, steroids, phospholipids q Fats=glycerol + 3 fatty acids (linked by
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