Carbohydrates and Lipids
Chapter 5: Macromolecules Macromolecules Smaller organic molecules join together to form larger molecules o macromolecules 4 major classes of macromolecules: o Carbohydrates o Lipids o Proteins o Nucleic acids Polymers Long molecules built by linking chain of repeating smaller units o monomers = repeated small units o Covalent bonds How to Build a Polymer Condensation Reaction o Dehydration synthesis o Joins monomers by taking H 2 O out 1 monomer provides OH the other monomer provides H together these form H 2 O o Requires energy & enzymes How to Break Down a Polymer Hydrolysis o Use H 2 O to break apart monomers Reverse of condensation reaction H 2 O is split into H and OH H & OH group attach where the covalent bond used to be. o ex: Digestion is hydrolysis. Carbohydrates Carbohydrates are composed of C, H, O carbo - hydr - ate CH 2 O (CH 2 O) x C 6 H 12 O 6 Function: o energy energy storage o raw materials structural materials Monomer: sugars o ex: sugars & starches 1
Sugars Most names for sugars end in -ose Classified by number of carbons o 6C = hexose (glucose) o 5C = pentose (fructose, ribose) o 3C = triose (glyceraldehyde) What functional groups are used? o Carbonyl- Ketones and Aldehydes o Hydroxyl Sugar Structure 5C & 6C sugars form rings in aqueous solutions Carbons are numbered. 2
Simple & Complex Sugars Monosaccharides o Simple 1 monomer sugars o Glucose Disaccharides o 2 monomers o Sucrose Polysaccharides o Large polymers o Starch Building Sugars Dehydration Synthesis Polysaccharides Polymers of Sugars o Costs little energy to build o Easily reversible = release energy Function: o Energy Storage starch (plants) glycogen (animals) o Building Materials = structure cellulose (plants) chitin (arthropods & fungi) Polysaccharide Diversity Molecular structure determines function o Isomers of glucose o How does structure influence function 3
Digesting Starch vs. Cellulose Cellulose Most abundant organic compound on Earth. Glycemic Index Ranking of carbohydrates based on their immediate effect on blood glucose (blood sugar) levels Carbohydrate foods that breakdown quickly during digestion have the highest glycemic indices. Their blood sugar response is fast & high. Which food will get into your blood more quickly? o apple 36 o rice cakes 82 o corn flakes 84 o bagel 72 o peanut M&M 33 4
Chapter 5 Macromolecules: Lipids Lipids Lipids are composed of C, H, O o Long hydrocarbon chain Diverse Group Fats Phospholipids Steroids Do not form polymers o Big molecules made of subunit smaller molecules. o Not a continuing chain. Fats Structure: o Glycerol (3C alcohol) + fatty acid Fatty acid = long HC tail with COOH group at head. Triacylglycerol o 3 fatty acids linked to glycerol. o Ester linkage = between OH & COOH. 1
Long HC Chain o Polar or non-polar? o Hydrophilic or hydrophobic? Function: o Energy storage very rich 2x carbohydrates o Cushion organs o Insulates body Think whale blubber! Saturated Fats All C bonded to H No C=C double bonds o long, straight chain o most animal fats o solid at room temp. contributes to cardiovascular disease (atherosclerosis) = plaque deposits Unsaturated Fats C=C double bonds in the fatty acids o Plant & fish fats o Vvegetable oils o Liquid at room temperature The kinks made by double bonded C prevent the molecules from packing tightly together. Phospholipids Structure: Glycerol + 2 fatty acids + PO 4 o PO 4 negatively charged o other small molecules may also be attached Adenine (ATP) Hydrophobic or hydrophilic? o Fatty acid tails = hydrophobic o PO 4 = hydrophilic head o Dual personality o interaction with H 2 O is complex & very important! 2
Phospholipids in Water Hydrophilic heads attracted to H 2 O Hydrophobic tails hide from H 2 O o self-assemble into aggregates micelle liposome Early evolutionary stage of cell? Why is this important? o Phospholipids define outside vs. inside o Where do we find phospholipids in cells? Cell membranes Phospholipids & Cells Phospholipids of Cell Membrane o Double layer = bilayer o Hydrophilic heads on outside In contact with aqueous solution o Hydrophobic tails on inside Form core o Forms barrier between cell & external environment. 3
Steroids ex: cholesterol, sex hormones 4 fused C rings o different steroids created by attaching different functional groups to rings. Diversity in Steroids Cholesterol Important cell component o Animal cell membranes Helps keep cell membranes fluid & flexible o Precursor of all other steroids Including vertebrate sex hormones. o High levels in blood may contribute to cardiovascular disease. 4