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Macromolecular Structures. Really Big Molecules. Macromolecular Structures. Types of Macromolecular Structures Covalent Network Systems Polymers Plastics Biomolecules. Covalent Network. Covalent Network Solids. Systems of Interlocking Covalent Bonds Not Individual Molecules
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Macromolecular Structures Really Big Molecules
Macromolecular Structures • Types of Macromolecular Structures • Covalent Network Systems • Polymers • Plastics • Biomolecules
Covalent Network Solids • Systems of Interlocking Covalent Bonds • Not Individual Molecules • All have very high melting points • Examples • Carbon • Graphite • Diamond • Nanotubes • Silicon • Silicon dioxide • Silica, Glass, Quartz
Graphite • Massive Sets of Fused 6 membered rings Jmol
Graphite • Properties • Good lubricant • Conducts electricity • Very high melting point
Diamond • Tetrahedral repeating pattern • Very strong network of bonds • Diamond is the hardest substance known. Jmol
Carbon Nanotubes • Similar structure to graphite • Sheet of 6 membered rings rolled into a tube. • Have high melting points • Very high strength • High conductivity
Buckeyballs • Not a covalent network • C60 molecule • Many other possible spherical arrangements • Fullerenes Jmol
Silica • Has an empirical formula of SiO2 • Has a repeating tetrahedral structure • Oxygens are parts of multiple tetrahedra. • Gives glass and sand their high melting points. Jmol
Polymers • “poly-” = many • “mer” from meros = part • Polymer – a chemical compound formed from many smaller molecules. Requires a little bit of organic chemistry shorthand.
Organic Shorthand • Drawing all those hydrogens gets tedious • Condense them • Use a line notation • Each red dot represents a carbon • It is understood that each carbon has an octet filled out with hydrogen unless otherwise noted.
Plastics • Polymers made from small organic molecules • Organic compounds are made from carbon.
Polyethylene • Made from ethylene molecules • Used in milk cartons (HDPE) • 6 pack plastic rings (LDPE) Jmol
Polypropylene • Made from propylene • Used in clothing and Gladware type containers. Jmol
Polyethylene terephthalate • Has two monomers • Ethylene • Terephthalic acid • Used in soda bottles (PETE or PET)
Teflon • Polytetrafluoroethylene • Due to high electronegativity of fluorine, the structure is not very susceptible to forming an induced dipole • Makes a very slippery surface Jmol
Polystyrene • Made from styrene monomers • Can be fluffed • Styrofoam • Can be compact • Drink lids
Biopolymers • Polymers made from biomolecules • 4 Basic Types of Biomolecules • Amino Acids • Proteins are amino acid polymers • Carbohydrates • Starch and Cellulose are carbohydrate polymers • Lipids • Nucleic Acids • DNA and RNA are nucleic acid polymers
Amino Acids • Named for two parts of the structure • Amine functional group • Carboxylic acid functional group
Amino Acids • The different amino acids are different in one location • R is just a place holder • The R group in this particular case is called a “side chain”
Polymerizing Amino Acids Peptide Bond
Aspartame • Nutrasweet • Aspartic acid • Phenylalanine
Protein Structure • Proteins fold in on themselves. • They fold so that • Nonpolar side chains are on the interior of the protein (away from water) • Polar side chains are on the exterior of the protein.
Proteins • Hemoglobin • Collagen Jmol
Carbohydrates • Names comes from observation about formulas • C6H12O6 – Glucose/Fructose/Galactose • C12H22O11 – Sucrose • C5H10O5 – Ribose • All have a 2:1 ratio of H:O
Carbohydrate Polymers • The most important carbohydrate polymers have glucose monomers • Starch • Amylose • Amylopectin • Cellulose • These differ only by how the glucose molecules connect.
Starch • Used for glucose storage in plants • Amylose – linear structure • Amylopectin – branched structure
Cellulose • Linear polymer • Forms cell wall of plants. • Indigestible by humans
Why are they different? • Why is starch digestible and celluose isn’t? • We have the enzyme necessary to break this bond. • We lack the enzyme necessary to break down this bond.
Nucleic Acids Nucleic acid monomers are nucleotides • Nitrogenous base • Pentose (sugar with 5 carbons) • Ribose = RNA • Deoxyribose = DNA • Phosphate
DNA Double Helix Jmol
RNA • RNA can base pair too. • RNA can form helical structures too Jmol
RNA and Protein Together • Ribosome