The reactions of the tricarboxylic acid (TCA) cycle allow the controlled combustion of fat and
carbohydrate. In principle, TCA cycle intermediates are regenerated on every turn and can
facilitate the oxidation of an infinite number of nutrient molecules. However, TCA cycle
intermediates can be lost to cataplerotic pathways that provide precursors for biosynthesis,
and they must be replaced by anaplerotic pathways that regenerate these intermediates.
Together, anaplerosis and cataplerosis help regulate rates of biosynthesis by dictating …