Lipids: Chapter 11 1. Characterize physiological roles of lipids a. Lipids are a very diverse class i. There is no structural template because they are extremely varied ii. These classes are defined by solubility b. Hydrophobicity contributes to cellular roles i. It is the one common thing held by all lipids c. Lipids largely lack a variety of functional groups d. Some general functions are: i. Sources of energy 1. They are highly reducible giving off a lot of energy 2. Their hydrophobic nature make it ideal for packing ii. Insulation from the environment 1. Low thermal conductivity 2. High heat capacity (can absorb heat) 3. Mechanical protection (can absorb shock) iii. Water repellant 1. Keeps water in and keeps us dry iv. Membrane structure 1. They are the main component of the cell membrane v. Signaling molecules 1. Steroids and other hormones can act as signals producing a signal transduction cascade leading to possible physiological changes 2. GFs or growth factors can also be lipids acting in a similar fashion to steroid hormones 3. Proinflammatory markers 2. Here are a few questions to help identify an unknown lipid. Knowing its class can tell a lot about its structurefunction a. Is there a fatty acid present? i. Things that dont are cholesterol and steroid hormones ii. Those that do are storagemembrane lipid iii. These are just samples you can use to help navigate lipid classification b. Is the lipid a membrane component? Signaling molecule?