Primary metabolites are compounds that are directly involved in the normal growth, development, and reproduction of organisms. They are essential for the cell's basic functions and are typically produced during the growth phase. Examples of primary metabolites include:



  1. Amino acids - building blocks of proteins (e.g., glycine, alanine)
  2. Carbohydrates - energy sources and structural components (e.g., glucose, starch)
  3. Lipids - energy storage and membrane structure (e.g., fatty acids, triglycerides)
  4. Nucleotides - DNA and RNA components (e.g., adenine, thymine)
  5. Organic acids - intermediates in metabolic cycles (e.g., citric acid in the Krebs cycle)

Secondary metabolites are compounds that are not directly involved in growth or reproduction but usually play a role in ecological interactions, such as defense mechanisms or signaling. They are often produced during the stationary phase of growth. Examples of secondary metabolites include:

  1. Alkaloids - nitrogen-containing compounds with pharmacological effects (e.g., morphine, caffeine)
  2. Terpenoids - large class of organic chemicals often used in plant defense (e.g., menthol, limonene)
  3. Phenolics - compounds with antioxidant properties (e.g., flavonoids, tannins)
  4. Antibiotics - substances produced by microorganisms to inhibit the growth of others (e.g., penicillin, streptomycin)
  5. Pigments - used for coloration and protection (e.g., chlorophyll, carotenoids)