1. Glycerol: This is a three-carbon alcohol molecule with three hydroxyl (OH) groups.

2. Fatty acids: These are long chains of hydrocarbons with a carboxyl group (COOH) at one end.

When these two molecules combine, they form a triglyceride, which is the basic unit of fat. Three fatty acid molecules attach to each glycerol molecule, with the carboxyl group of each fatty acid bonding to a hydroxyl group on the glycerol. This process is called esterification, and it releases a water molecule for each bond formed.