[Sophomore Biology: Organic Molecules Menu]


*They are organic molecules non-dissolvable in H2O.

*Lipids contain many C-H bonds which store energy (calories).


Most contain fatty acids (long chains of C-H bonds ending in COOH) which are then bonded to Glycerol.


Saturated Fatty Acid (F.A.)- all bonds are C-C or C-H. Contains more energy, thus more fattening.

Unsaturated F.A.- some bonds may be C=C. Contains less energy, less fattening.

Types of Lipids:

A. Triglycerides: Made of glycerol & 3 fatty acids. (EX. Fats & oils)


B. Phospholipids: Glycerol, 2 fatty acids, & 1 phosphate group (PO4). (Ex.-Cell membranes)


C. Wax: Fatty Acid & an alcohol group (OH).

D. Steroids: Consist of four 5- or 6-sided carbon rings joined together. Has no fatty acids. (Ex.- Cholesterol, hormones)

A simple diagram of a steroid.

Importance of Lipids:

1. Energy storage- Fats store glucose energy for long time periods. Highest calorie values per weight.

2. Chemical messengers- Steroid hormones (testosterone & estrogen)

3. Cell membranes (flexible, protective outer covering of cells).