Macromolecular Structures Really Big Molecules Macromolecular Structures l
Macromolecular Structures Really Big Molecules
Macromolecular Structures l Types of Macromolecular Structures l Covalent Network Systems l Polymers l Plastics l Biomolecules
Covalent Network
Covalent Network Solids Systems of Interlocking Covalent Bonds l Not Individual Molecules l All have very high melting points l Examples l l Carbon l Graphite l Diamond l Nanotubes l Silicon dioxide l Silica, Glass, Quartz
Graphite l Massive Sets of Fused 6 membered rings Jmol
Graphite l Properties l Good lubricant l Conducts electricity l Very high melting point
Diamond l Tetrahedral repeating pattern l Very strong network of bonds l Diamond is the hardest substance known. Jmol
Carbon Nanotubes l Similar structure to graphite l Sheet of 6 membered rings rolled into a tube. l Have high melting points Very high strength High conductivity l l
Buckeyballs l Not a covalent network l C 60 molecule l Many other possible spherical arrangements l Fullerenes Jmol
Silica l Has an empirical formula of Si. O 2 l Has a repeating tetrahedral structure l Oxygens l are parts of multiple tetrahedra. Gives glass and sand their high melting points. Jmol
Polymers
Polymers “poly-” = many l “mer” from meros = part l l Polymer – a chemical compound formed from many smaller molecules. Requires a little bit of organic chemistry shorthand.
Organic Shorthand l Drawing all those hydrogens gets tedious l Condense them l Use a line notation Each red dot represents a carbon l l It is understood that each carbon has an octet filled out with hydrogen unless otherwise noted.
Plastics l Polymers made from small organic molecules l Organic compounds are made from carbon.
Polyethylene l Made from ethylene molecules l Used in milk cartons (HDPE) 6 pack plastic rings (LDPE) l Jmol
Polypropylene l Made from propylene l Used in clothing and Gladware type containers. Jmol
Polyethylene terephthalate l Has two monomers l l l Ethylene Terephthalic acid Used in soda bottles (PETE or PET)
Teflon l Polytetrafluoroethylene l Due to high electronegativity of fluorine, the structure is not very susceptible to forming an induced dipole l Makes a very slippery surface Jmol
Polystyrene l Made from styrene monomers l Can be fluffed l l Styrofoam Can be compact l Drink lids
Biopolymers
Biopolymers Polymers made from biomolecules l 4 Basic Types of Biomolecules l l Amino Acids l Proteins are amino acid polymers l Carbohydrates l Starch and Cellulose are carbohydrate polymers l Lipids l Nucleic l DNA Acids and RNA are nucleic acid polymers
Amino Acids l Named for two parts of the structure l Amine functional group l Carboxylic acid functional group
Amino Acids l The different amino acids are different in one location l R is just a place holder l The R group in this particular case is called a “side chain”
Amino Acids
Amino Acids
Polymerizing Amino Acids Peptide Bond
Aspartame l Nutrasweet l Aspartic acid l Phenylalanine
Protein Structure l Proteins fold in on themselves. l They fold so that l l Nonpolar side chains are on the interior of the protein (away from water) Polar side chains are on the exterior of the protein.
Proteins l Hemoglobin l Collagen Jmol
Carbohydrates l Names comes from observation about formulas l C 6 H 12 O 6 – Glucose/Fructose/Galactose l C 12 H 22 O 11 – Sucrose l C 5 H 10 O 5 – Ribose l All have a 2: 1 ratio of H: O
Carbohydrate Polymers l The most important carbohydrate polymers have glucose monomers l Starch l l Amylose Amylopectin l Cellulose l These differ only by how the glucose molecules connect.
Starch l l l Used for glucose storage in plants Amylose – linear structure Amylopectin – branched structure
Cellulose l Linear polymer l Forms cell wall of plants. l Indigestible by humans
Why are they different? l Why is starch digestible and celluose isn’t? l We have the enzyme necessary to break this bond. l We lack the enzyme necessary to break down this bond.
Nucleic Acids Nucleic acid monomers are nucleotides 1. Nitrogenous base 2. Pentose (sugar with 5 carbons) l l 3. Ribose = RNA Deoxyribose = DNA Phosphate
Nucleotide Polymerization
Nucleic Acid Structure
DNA Base Pairs
DNA Double Helix Jmol
RNA l l Jmol RNA can base pair too. RNA can form helical structures too
RNA and Protein Together l Ribosome
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