Both the fatty acid and protein metabolism are linked to carbohydrate metabolism. Anabolism is the phase of intermediary metabolism concerned with the energy - requiring biosynthesis of cell components from smaller precursors. An example in higher animals is the formation of glycogen from glucose or it's intermediate metabolites. Catabolism is the degradative phase of metabolism. Catabolism and anabolism proceed simultaneously in a dynamic steady state.
Enzymes are biological catalyst that affect the rate of a reaction.
All the metabolites in the metabolic pathway are converted by enzymes to other metabolites.