Question

A typical fat molecule is made up of
A. Three glycerol molecule and one fatty acid molecule
B. One glycerol molecule and three fatty acid molecules
C. One glycerol molecule and one fatty acid molecule
D. Three glycerol molecule and three fatty acid molecule

Answer 1

Lipids (lipos – fat) include highly varied substances, like cooking oil, butter, ghee, waxes, cholesterol, essential oils, natural rubber etc. lipids are classified into-simple lipids. (Example: Neutral or true fats and waxes). Compound or conjugated lipids (phospholipids, glycolipids, lipoproteins, suberin, cutin) and derived lipids (steroids, terpenes etc.).

Complete answer:
Let us analyse the options and find the correct answer.

Option A, C and D: As a fat molecule is made up of one glycerol molecule and three fatty acid molecules, therefore, these options are incorrect.
Option B: Three hydroxyl (OH) groups of a glycerol molecule join with the carboxyl groups of three fatty acid molecules. Glycerol and fatty acid are linked by ester bonds by elimination of three water molecules. Therefore, this is the correct answer.
A glycerol molecule has 3 carbons, each bearing a hydroxyl (OH) group. Fatty acid molecule is an unbranched chain of carbon atoms, has a carboxyl group -COOH, hydrogen atoms are bonded to all carbon atoms, forming a hydrocarbon chain. Hydrocarbon chain does not dissolve in water as C-H bonds are nonpolar. The carboxyl group (COOH) gives acidic properties as it can dissociate into Hydrogen ions and -COOH groups.

Thus, the correct answer is option (B) One glycerol molecule and three fatty acid molecules.

Additional information: Neutral or true fats are composed of carbon, hydrogen and oxygen like carbohydrates but have far less oxygen atoms than carbon atoms unlike carbohydrates.
Fatty acid are of two types:
(a) Saturated fatty acid (all carbons are inter linked by single bond).
(b) Unsaturated fatty acid (all carbons are interlinked by double bond).

Note: Most animal fats are 16- carbon palmitic acid and 18-carbon stearic acid. The neutral fats formed with these fatty acids are tripalmitin and tristearin.
Most plant and fish lipids have unsaturated fatty acids and most animal fats have saturated fatty acids. Saturated fats lead to atherosclerosis in humans, thus have bad effects on health, so their use should be minimised.