hold fats together in biological systems and bond fatty acids to glycerol.HydroxylsCarbonylsAmines EstersEthers

In biological systems, the main molecules that hold fats together and bond fatty acids to glycerol are Esters.

Explanation:

1. Esters Formation: Fats, also known as triglycerides, are formed through a chemical reaction between glycerol and fatty acids. This reaction is called esterification, where the hydroxyl group of glycerol reacts with the carboxyl group of fatty acids to form ester bonds.

2. Structure of Triglycerides: Each triglyceride molecule consists of one glycerol molecule and three fatty acid molecules. The glycerol has three hydroxyl (-OH) groups, and each fatty acid has a carboxyl (-COOH) group. The formation of ester bonds results in the release of water molecules, hence making the process a condensation reaction.

3. Importance in Biology: These esters are significant because they store energy, provide insulation, and play crucial roles in cell membrane structure.

To summarize, Esters are the compounds that primarily hold fats together in biological systems by bonding fatty acids to glycerol through the formation of ester linkages.