Why is the conversion of a triglyceride molecule to fatty acids and glycerol a catabolic hydrolysis reaction? Would the reverse anabolic reaction generate water?
The correct answer and explanation is:
Correct Answer:
The conversion of a triglyceride molecule to fatty acids and glycerol is a catabolic hydrolysis reaction because it breaks down a large molecule into smaller units using water. Yes, the reverse anabolic reaction would generate water.
Explanation:
The breakdown of a triglyceride into fatty acids and glycerol is classified as a catabolic reaction because it involves the decomposition of a complex molecule into simpler ones. Triglycerides are large lipid molecules composed of one glycerol backbone bonded to three fatty acid chains. During digestion or metabolic breakdown, enzymes such as lipases catalyze the cleavage of the ester bonds that link the fatty acids to the glycerol. This process requires the addition of water molecules and is known as hydrolysis.
Each ester bond in a triglyceride requires one molecule of water to be broken. The water splits, with the hydroxyl group (OH⁻) attaching to the fatty acid and the hydrogen ion (H⁺) attaching to the glycerol. The result is the release of free fatty acids and a glycerol molecule. Since this reaction releases energy and reduces a large molecule into smaller components, it is a catabolic process.
In contrast, the reverse process, where fatty acids and glycerol combine to form a triglyceride, is an anabolic reaction. Anabolic reactions build larger molecules from smaller subunits and typically require energy. When a triglyceride is formed, the reaction joins fatty acids and glycerol by forming ester bonds through a process known as dehydration synthesis or condensation. This means that for each ester bond formed, one water molecule is removed.
Therefore, the anabolic formation of a triglyceride from fatty acids and glycerol does generate water molecules as by-products. The process is energy-requiring and involves enzyme-catalyzed synthesis, the opposite of the hydrolysis seen in catabolic pathways.