Macromolecular Structures Really Big Molecules

Macromolecular Structures Types of Macromolecular Structures Types of Macromolecular Structures Covalent Network Systems Covalent Network Systems Polymers Polymers Plastics Plastics Biomolecules Biomolecules

Covalent Network

Covalent Network Solids Systems of Interlocking Covalent Bonds Systems of Interlocking Covalent Bonds Not Individual Molecules Not Individual Molecules All have very high melting points All have very high melting points Examples Examples Carbon Carbon Graphite Graphite Diamond Diamond Nanotubes Nanotubes Silicon Silicon Silicon dioxide Silicon dioxide Silica, Glass, Quartz Silica, Glass, Quartz

Graphite Massive Sets of Fused 6 membered rings Massive Sets of Fused 6 membered rings Jmol

Graphite Properties Properties Good lubricant Good lubricant Conducts electricity Conducts electricity Very high melting point Very high melting point

Diamond Tetrahedral repeating pattern Tetrahedral repeating pattern Very strong network of bonds Very strong network of bonds Diamond is the hardest substance known. Diamond is the hardest substance known. Jmol

Carbon Nanotubes Similar structure to graphite Similar structure to graphite Sheet of 6 membered rings rolled into a tube. Sheet of 6 membered rings rolled into a tube. Have high melting points Have high melting points Very high strength Very high strength High conductivity High conductivity

Buckeyballs Not a covalent network Not a covalent network C 60 molecule C 60 molecule Many other possible spherical arrangements Many other possible spherical arrangements Fullerenes Fullerenes Jmol

Silica Has an empirical formula of SiO 2 Has an empirical formula of SiO 2 Has a repeating tetrahedral structure Has a repeating tetrahedral structure Oxygens are parts of multiple tetrahedra. Oxygens are parts of multiple tetrahedra. Gives glass and sand their high melting points. Gives glass and sand their high melting points. Jmol

Polymers

Polymers “poly-” = many “poly-” = many “mer” from meros = part “mer” from meros = part Polymer – a chemical compound formed from many smaller molecules. 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 Drawing all those hydrogens gets tedious Condense them Condense them Use a line notation Use a line notation Each red dot represents a carbon Each red dot represents a carbon It is understood that each carbon has an octet filled out with hydrogen unless otherwise noted. It is understood that each carbon has an octet filled out with hydrogen unless otherwise noted.

Plastics Polymers made from small organic molecules Polymers made from small organic molecules Organic compounds are made from carbon. Organic compounds are made from carbon.

Polyethylene Made from ethylene molecules Made from ethylene molecules Used in milk cartons (HDPE) Used in milk cartons (HDPE) 6 pack plastic rings (LDPE) 6 pack plastic rings (LDPE) Jmol

Polypropylene Made from propylene Made from propylene Used in clothing and Gladware type containers. Used in clothing and Gladware type containers. Jmol

Polyethylene terephthalate Has two monomers Has two monomers Ethylene Ethylene Terephthalic acid Terephthalic acid Used in soda bottles (PETE or PET) Used in soda bottles (PETE or PET)

Teflon Polytetrafluoroethylene Polytetrafluoroethylene Due to high electronegativity of fluorine, the structure is not very susceptible to forming an induced dipole Due to high electronegativity of fluorine, the structure is not very susceptible to forming an induced dipole Makes a very slippery surface Makes a very slippery surface Jmol

Polystyrene Made from styrene monomers Made from styrene monomers Can be fluffed Can be fluffed Styrofoam Styrofoam Can be compact Can be compact Drink lids Drink lids

Biopolymers

Biopolymers Polymers made from biomolecules Polymers made from biomolecules 4 Basic Types of Biomolecules 4 Basic Types of Biomolecules Amino Acids Amino Acids Proteins are amino acid polymers Proteins are amino acid polymers Carbohydrates Carbohydrates Starch and Cellulose are carbohydrate polymers Starch and Cellulose are carbohydrate polymers Lipids Lipids Nucleic Acids Nucleic Acids DNA and RNA are nucleic acid polymers DNA and RNA are nucleic acid polymers

Amino Acids Named for two parts of the structure Named for two parts of the structure Amine functional group Amine functional group Carboxylic acid functional group Carboxylic acid functional group

Amino Acids The different amino acids are different in one location The different amino acids are different in one location R is just a place holder R is just a place holder The R group in this particular case is called a “side chain” The R group in this particular case is called a “side chain”

Amino Acids

Polymerizing Amino Acids Peptide Bond

Aspartame Nutrasweet Nutrasweet Aspartic acid Aspartic acid Phenylalanine Phenylalanine

Protein Structure Proteins fold in on themselves. Proteins fold in on themselves. They fold so that They fold so that Nonpolar side chains are on the interior of the protein (away from water) Nonpolar side chains are on the interior of the protein (away from water) Polar side chains are on the exterior of the protein. Polar side chains are on the exterior of the protein.

Proteins Hemoglobin Hemoglobin Collagen Collagen Jmol

Carbohydrates Names comes from observation about formulas Names comes from observation about formulas C 6 H 12 O 6 – Glucose/Fructose/Galactose C 6 H 12 O 6 – Glucose/Fructose/Galactose C 12 H 22 O 11 – Sucrose C 12 H 22 O 11 – Sucrose C 5 H 10 O 5 – Ribose C 5 H 10 O 5 – Ribose All have a 2:1 ratio of H:O All have a 2:1 ratio of H:O

Carbohydrate Polymers The most important carbohydrate polymers have glucose monomers The most important carbohydrate polymers have glucose monomers Starch Starch Amylose Amylose Amylopectin Amylopectin Cellulose Cellulose These differ only by how the glucose molecules connect. These differ only by how the glucose molecules connect.

Starch Used for glucose storage in plants Used for glucose storage in plants Amylose – linear structure Amylose – linear structure Amylopectin – branched structure Amylopectin – branched structure

Cellulose Linear polymer Linear polymer Forms cell wall of plants. Forms cell wall of plants. Indigestible by humans Indigestible by humans

Why are they different? Why is starch digestible and celluose isn’t? Why is starch digestible and celluose isn’t? We have the enzyme necessary to break this bond. We have the enzyme necessary to break this bond. We lack the enzyme necessary to break down this bond. 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) Ribose = RNA Ribose = RNA Deoxyribose = DNA Deoxyribose = DNA 3. Phosphate

Nucleotide Polymerization

Nucleic Acid Structure

DNA Base Pairs

DNA Double Helix Jmol

RNA RNA can base pair too. RNA can base pair too. RNA can form helical structures too RNA can form helical structures too Jmol

RNA and Protein Together Ribosome Ribosome