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Top 10 Inventions of The Millennium • • • • • • • Eraser Hay The Stirrup Reading Glasses Classical Music Birth control pills Transistor Sodium Polyacrylate Applications • Absorbs 80x its molecular weight in water • Used to fight forest fires • Assists in germinating seeds in arid/dry environments Why Does Sodium Polyacrylate Work? • Individual sodium polyacrylate molecules are virtually useless • Connected into long chains, water molecules are trapped between sodium atoms Polyethylene • Arrangement of styrene units into long chains • Allows strength in longitudinal directions • Lack of connections between chains makes lateral aspects weak What Is A Polymer? Polymers Defined • Substances made of three or more identical units • The individual unit is called a monomer; two units are called dimers • As more monomers are linked, the properties of the substance changes Gunther VonHagens 1993 Hamburg Exhibition of Polymer Art The Body As Polymer Four Classes of Biopolymers • • • • Carbohydrates Lipids Nucleic Acids Proteins Organic v. Inorganic • INORGANIC • Lack the element carbon • Ex: NaCl, H20, HF • ORGANIC • Contains the element carbon • Ex: CO2, C6H12O6 Why Are All Four Biopolymer Classes Organic? The Molecular Architecture of Carbon • High abundance in biosphere • Tetravalent electron arrangement (4 e- in 2nd valence shell) • Moderate electronegativity means carbon is unlikely to form ionic bonds Carbon The Compromiser • Carbon shares 4 pairs of electrons with other atoms covalently • This high number of bonds means many other atoms can be linked to carbon • Covalent bonds useful in biopolymers for resisting entropy • Silicon is also tetravalent • Silicon (in the form of silica) is frequently incorporated into living organisms as crystals, spikes or spines • However, its lower abundance in the lithosphere may explain carbon’s dominance ISOMERIZATION • Because carbon can form so many covalent bonds, substances with many carbon atoms can be arranged in many ways • Isomers are substances with the same number and type of atoms but a different structural arrangement/formula Polymerization Reactions Polymerization By Condensation • A hydrogen atom (H) is removed from one monomer • A hydroxyl (-OH) group is removed from the other monomer • Hydrogen and hydroxyl join to form water • The remaining monomers are covalently linked to form a dimer Dehydration Synthesis Kinematics • Energy required to make bonds form • This is called an ENDERGONIC reaction • About 200mL of water/day is synthesized in the human body as a result of endergonic reactions HYDROLYSIS • Literally means “to split using water” • The converse of dehydration synthesis • A water molecule splits into H and OHgroups • The polymer is divided into monomers The Kinematics of Hydrolysis • Since the two monomers have less potential energy than the original polymer, energy is “released” • This is called an EXERGONIC reaction • Hydrolysis requires energy to be put in at the start but more energy is freed at the end If all biopolymers are constructed and destructed in the same way, what makes them different? Different Organic Substances Have Different Functional Groups Carbohydrates General Characteristics of Carbohydrates • Literally means ‘water added to carbon” • Contains ONLY carbon, hydrogen and oxygen atoms in empirical formula • Ratio of hydrogen to oxygen in empirical formulae is generally 2:1 (i.e. C6H12O6) • Have caloric value of appx. 4 cal/gram • May be used for energy flow or structure Monosaccharides • Literally translates as “single sugars” • Monomers/building blocks of carbohydrate polymers • Three different forms/isomers: glucose, fructose and galactose Glucose • Need 9grams/15 minutes of metabolism in bloodstream • Can only be let into cells via the action of the hormone insulin • Does not taste sweet Fructose • Common natural sugar found in fruits and honey • Does taste sweet Glucose v. Fructose Glucose v. Galactose Disaccharides • “Double sugars” • Formed from the condensation reaction between two monosaccharides • Water is removed as a result of dehydration synthesis • Examples: Maltose, Lactose, Sucrose The bond between monosaccharides is called a GLYCOSIDIC linkage Sucrose • Formed from condensation of glucose and fructose • Table sugar • Does taste sweet Lactose • Formed by linking glucose to galactose • 20% of U.S. population cannot hydrolyze the glycosidic linkage in lactose • Lactose intolerance Maltose • Formed by linking two glucose units together • Common disaccharide in plants as intermediate storage form of glucose made in photosynthesis • Does not taste sweet • Starches consist of hundreds of glucose units connected with an alpha glycosidic linkage • Cellulose contains equal numbers of glucose units but has a beta glycosidic linkage • The beta linkage is indigestible in most organisms without the proper enzymes Characteristics of Proteins • Contain carbon, hydrogen, oxygen and nitrogen atoms • Are generally used for structural purposes in living organisms but may also be used for energy flow • 4 cal/gram if used for metabolism • Highly folded structures held in place with combination of strong covalent bonds and weak intermolecular forces There are 20 different Amino Acids: The building blocks of proteins Amino Acid Form & Function • Contain CARBOXYL (COOH) and AMINE functional groups • The 20 A.A. differ in the structure and complexity of their side groups (R-) • 16 A.A. synthesized in body / 4 must come from diet • All 20 needed to create the proteins necessary for life Phenylalanine Tryptophan Synthesis of A Dipeptide • Two A.A. monomers are joined by removing the hydrogen from one amine group and a hydroxide ion from the carboxyl group of another atom • One water molecule is formed/condensed • The resulting linkage is a strong bond called a PEPTIDE BOND Polypeptide Formation Levels of Peptide Structure • Primary: Sequence of A.A. held by peptide bonds • Secondary: Coiled A.A. chain held by disulfide and hydrogen bonds • Tertiary: Folded coil of A.A. held by hydrogen bonds • Quaternary: Globular shape held by hydrogen, VanderWaal and other intermolecular forces Ex: Levels of Structure In Proteins Preserving this quaternary structure is one of the prime components of homeostasis LIPIDS Characteristics of Lipids • Comprised of only carbon, hydrogen and oxygen atoms • Ratio of hydrogen to oxygen is always GREATER than 2:1 • Caloric value of lipids is appx. 9 cal/gram • Lipids good for long-term storage of energy due to non-polar structure, high caloric value and density Lipids are comprised of 3 fatty acid monomers linked to a glycerol molecule Bonding In Fats • Each fatty acid loses a hydroxyl (OH-) group • The glycerol backbone loses 3 hydrogen atoms • Three water molecules are condensed • The fatty acids and glycerol combine as an ESTER LINKAGE Saturated v. Unsaturated Fats • Saturated Fats • All carbon atoms are bonded to four other atoms via single bonds • Saturated fats tend to be solid and dense • Often derived from animals • Atherosclerosis and obesity may result from overconsumption • Unsaturated Fats • Some carbon atoms share more than one pair of electrons • This is called a double bond or unsaturation • Unsaturated fats tend to be liquids/oils and often come from plants or aquatic animals Saturated, Unsaturated and Polyunsaturated Fats Excess saturated fat is stored in large cells called Adipocytes Fatty acids may also combine with charged phosphate groups to create phospholipids, which simultaneously attract and repel water If heated, the glycerol in fats is changed into a carcinogen called acrolein which causes digestive distress/heartburn