Lipids Hydrophobic Elements: C H O Ratio of H:O= H greater than O C 57 H 110 O 6

Characteristics Insoluble in water (they are non-polar) Main Purpose: energy storage molecules (Fat) Can act as chemical messengers within and between cells Focus will be on fats, phospholipids, and steroids

“Fats” -- Triglycerides Made of two kinds of smaller molecules – glycerol and fatty acids (one glycerol to three fatty acids) Dehydration synthesis hooks these up – 3 waters produced for every one triglyceride glycerol Fatty Acid Tails

Figure 5.10 The synthesis and structure of a fat, or triacylglycerol

Figure 5.11 Examples of saturated and unsaturated fats and fatty acids Figure 5.11 Examples of saturated and unsaturated fats and fatty acids

Fat vs. Oil Fats these are solid at room temperature – Lard & Butter Plants and fish have unsaturated triglycerides, so are liquid at room temp – oil

Figure 5.11x Saturated and unsaturated fats and fatty acids: butter and oil

Are lipids “Bad?” Major function is energy storage Ex. 1 Gram of fat stores more than TWICE the energy of a gram of polysaccaharide Adipose tissue provides cushioning for organs and insulation for body

Steroids Characterized by four fused carbon rings Cholesterol – found in cell membranes of animals Many hormones are steroids – sex hormones

Figure 5.14 Cholesterol, a steroid Figure 5.14 Cholesterol, a steroid