Lipids!

Examples Examples fats oils waxes hormones sex hormones testosterone (male) estrogen (female)

Lipids: the concentrated energy molecule Function: 1. energy storage (in C-H bond) very concentrated twice the energy as carbohydrates 2. cell membrane 3. cushions organs 4. insulates body think whale blubber

A little more on lipids… Structure: composed of C, H, O long hydrocarbon chains (H-C) “Family groups” fats phospholipids steroids Lipids ≠ Polymers BIG molecules of smaller subunits; NOT a continuing chain

1. Fats Structure: glycerol (3C alcohol) + fatty acid **fatty acid = long HC “tail” & carboxyl (COOH) “head”** enzyme H2O

Triglycerides – 3 fatty acids + glycerol Example: Triacylglycerol Building Fats Triglycerides – 3 fatty acids + glycerol Example: Triacylglycerol C – O – C bond = Ester Linkage via dehydration synthesis

ALL carbons bonded to 4 atoms Carbons NOT bonded 4 atoms Saturated vs. Unsaturated Fats Saturated ALL carbons bonded to 4 atoms Unsaturated Carbons NOT bonded 4 atoms Single bonds Double bonds Straight chain Kinks

Saturated Unsaturated 

Amphipathic - fats with polar and nonpolar regions 2. Phospholipids Structure: glycerol + 2 fatty acids + PO4 ** PO4 = negatively charged ** Review: tail – polar/nonpolar? PO4 – polar/nonpolar? Amphipathic - fats with polar and nonpolar regions “attracted to water” “repelled by water”

Significance of phospholipids In water: can self-assemble into “bubbles” (micelles) form phospholipid bilayer cell evolution! creates barrier → form cell membranes!

3. Steroids Structure: 4 fused C rings + functional groups ** different structure = ? ** Examples: cholesterol, sex hormones cholesterol

Role of Cholesterol Component in animal cell membranes Precursor to other steroids (Ex: sex hormones)