Metabolism of Food

This is a tricky question because metabolism is a generalized term that refers to both the synthesis (anabolism) and breakdown (catabolism) of complex molecules. The question could be restated as: when complex molecules are synthesized is water always formed? The answer is no. Only carbohydrates and proteins release water when they are made into polymers.

However, fats, or lipids, do not always form water when a covalent bond is formed. First of all, there are several different kinds of fats including: simple fats, compound fats, derived fats, terpenes and prostaglandins. The first two fats usually contain a glycerol and at least one fatty acid. Fatty acids are chains of carbon atoms bonded to each other. When a fatty acid is combined to a glycerol, condensation occurs. Water may be formed when the other fats are synthesized, but then again, much of the bonding occurs between carbon molecules that do not form water when they combine.

• Why is the word anabolism used to refer to synthesis of organic chemicals?
• Why is the word catabolism used to refer to the breakdown of complex molecules?

Nucleic acids also do not release water when they are made into polymers.

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