Lipids

Mini LectureRadjewski

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 steroids1.Cholesterol – maintains fluidity in cell membranes2.Testosterone - hormone3.Estrogen - hormone4.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