The basic structure of a triglyceride is:

The basic structure of a triglyceride is:

• A. a phospholipid backbone with 3 fatty acid molecules attached via ester linkage
• B. a cholesterol backbone with 3 fatty acid molecules attached via ester linkage
• C. a glycerol backbone with 3 fatty acid molecules attached via ester linkage
• D. a fatty acid backbone with 3 glycerol molecules attached via ester linkage

Answer: (C)

At the heart of a triglyceride is a glycerol molecule acting as the backbone, to which three fatty acid molecules are attached through ester bonds. Each of glycerol’s three hydroxyl groups bonds to the carboxyl end of a fatty acid, forming three ester linkages. This yields three fatty acid tails on a single glycerol molecule, which is the hallmark of triglycerides and what is stored in adipose tissue. The alternative descriptions would describe a molecule with a phosphate-containing head group (phospholipid), a molecule built on a cholesterol framework, or a fatty acid chain serving as the backbone rather than glycerol; these do not describe triglycerides.

At the heart of a triglyceride is a glycerol molecule acting as the backbone, to which three fatty acid molecules are attached through ester bonds. Each of glycerol’s three hydroxyl groups bonds to the carboxyl end of a fatty acid, forming three ester linkages. This yields three fatty acid tails on a single glycerol molecule, which is the hallmark of triglycerides and what is stored in adipose tissue. The alternative descriptions would describe a molecule with a phosphate-containing head group (phospholipid), a molecule built on a cholesterol framework, or a fatty acid chain serving as the backbone rather than glycerol; these do not describe triglycerides.