Which of the following are the most common building blocks of lipids?

• A. Monosaccharides and disaccharides
• B. Amino acids and nucleotides
• C. Peptides and polypeptides
• D. Fatty acids and glycerol

Answer: (D)

Verified step by step guidance

1. Understand the structure and function of lipids: Lipids are a diverse group of biomolecules that include fats, oils, phospholipids, and steroids. They are primarily composed of carbon, hydrogen, and oxygen atoms and serve as energy storage molecules, structural components of cell membranes, and signaling molecules.
2. Identify the building blocks of lipids: The most common building blocks of lipids are fatty acids and glycerol. Fatty acids are long hydrocarbon chains with a carboxyl group (-COOH) at one end, while glycerol is a three-carbon alcohol with hydroxyl groups (-OH) attached to each carbon.
3. Compare the options provided: Monosaccharides and disaccharides are carbohydrates, amino acids and nucleotides are building blocks of proteins and nucleic acids, and peptides and polypeptides are chains of amino acids. None of these are directly involved in forming lipids.
4. Explain the formation of lipids: Fatty acids and glycerol combine through esterification reactions to form triglycerides, which are a type of lipid. In this process, the hydroxyl groups of glycerol react with the carboxyl groups of fatty acids, releasing water molecules and forming ester bonds.
5. Conclude why fatty acids and glycerol are the correct answer: Fatty acids and glycerol are the fundamental components of most lipids, making them the correct answer to the question. This is consistent with the biochemical definition of lipids and their synthesis pathways.