Lipids Mini Lecture Radjewski

Lipids PDQ 1 Lipids are hydrocarbons (composed of C and H atoms); they are insoluble in water because of many nonpolar covalent bonds. When close together, weak but additive van der Waals interactions hold them together.

Functions of Lipids PDQ 2 Lipids Store energy in C—C and C—H bonds Play structural role in cell membranes Fat in animal bodies serves as thermal insulation

Triglycerides PDQ 3 Three fatty acids—nonpolar hydrocarbon chain attached to a polar carboxyl group (— COOH) (carboxylic acid) One glycerol—an alcohol with 3 hydroxyl (—OH) groups Synthesis of a triglyceride involves three condensation reactions.

PDQ 4 Fatty acid chains can vary in length and structure. In saturated fatty acids, all bonds between carbon atoms are single; they are saturated with hydrogens. In unsaturated fatty acids, hydrocarbon chains contain one or more double bonds. These acids cause kinks in the chain and prevent molecules from packing together tightly.

PDQ 6 Fatty acids are amphipathic; they have a hydrophilic end and a hydrophobic tail. Phospholipid—two fatty acids and a phosphate compound bound to glycerol The phosphate group has a negative charge, making that part of the molecule hydrophilic.

Figure 2.13 A Phospholipids

Figure 2.13 B Phospholipids

PDQ 5 Fatty acid – component in lipids Triglyceride – 3 fatty acids Phospholipids – 2 fatty acids

Steroids Examples of steroids 1.Cholesterol – maintains fluidity in cell membranes 2.Testosterone - hormone 3.Estrogen - hormone 4.Progesterone - hormone

Build a Triglyceride Remember triglycerides have: – 3 fatty acids – Glycerol molecule Do some condensation reactions. Attach water(s). Label one saturated fatty acid; unsaturated fatty acid; glycerol, and the ester bonds