Primary and Secondary Metabolites

A metabolite is generally a small organic molecule that is an intermediate or product of metabolism. Metabolites are grouped into two categories based on their role. Primary metabolites are directly required for the organism's basic, universal metabolic processes - photosynthesis, respiration, and protein and lipid metabolism - and include enzymes (e.g., protease, lipase, peroxidase), amino acids (e.g., proline, leucine), organic acids (e.g., acetic acid, lactic acid) and vitamins (A, B, C). Secondary metabolites, by contrast, have no direct role in an organism's own growth and development, but often serve ecological or defensive functions (such as deterring herbivores or attracting pollinators) and many have pharmacological importance to humans. This category includes pigments (carotenoids, anthocyanins), alkaloids (morphine, codeine), essential oils (le …