1.2 Lipids

LIPIDS • the four types of lipids are: 1) FATS and OILS 2) STEROIDS 3) WAXES 4) PHOSPHOLIPIDS • functions include: • energy storage/reserve; animals can convert excess carbohydrates to fats and store fat molecules in adipose tissue • protection of organs and insulation • major component of cell membranes • chemical messengers (hormones) • ALL lipids are HYDROPHOBIC/NONPOLAR MOLECULES FATS AND OILS • formed as a result of the condensation reaction between glycerol and 1,2 or 3 fatty acid molecules Figure 2. Fatty Acid Molecule – consists of a carboxyl functional group connected to a hydrocarbon chain Figure 1. Glycerol • Figure 2 is an example of a saturated fatty acid because there are only single bonds in the hydrocarbon chain • saturated fatty acids are linear molecules and as a result tend to be packed tightly together • this means that they are found in fats, substances that are solids at room temperature; i.e. butter, lard, blubber, coconut oil, fatty meats, etc. • associated with cardiovascular disease • unsaturated fatty acids have hydrocarbon chains that have one or more double bonds • this causes bending at the double bond and prevents molecules from packing tightly together • associated with oils, substances that are liquids at room temperature; i.e. olive oil, canola oil, vegetable oil, sunflower oil, etc. • associated with health benefits Examples of Fatty Acids FORMATION OF A FAT (TRIGLYCERIDE) • Glycerol + 3 Fatty Acids → Triglyceride + 3 Water Molecules An R group is An abbreviation for any group in which a carbon or hydrogen atom is attached to the rest of the molecule. Digestion/Hydrolysis of a Triglyceride + 3 H2O STEROIDS • Function as: Hormones (chemical messengers) – i.e. testosterone and estrogen Structural Component of Cell Membrane – cholesterol • Composed of a tetracyclic hydrocarbon skeleton, consisting of three fused six-membered rings and one five membered ring • differ in their side groups (R groups) and presence or absence of double bonds in their ring structures STRUCTURES OF SOME STEROIDS Testosterone WAXES • Result of condensation reaction between a large alcohol and fatty acid with very long hydrocarbon chain • protect against water loss and barrier to bacteria, insects PHOSPHOLIPIDS PHOSPHOLIPIDS PHOSPHOLIPIDS PHOSPHOLIPIDS