Lesson 4 of 14 · 5 min
Primary and secondary metabolites
NCERT §9.2
Turmeric, chilli, a strand of rubber band and a bottle of lemon grass oil sit on Farah's table. Kabir says each holds a compound the plant never needed just to stay alive.
The lesson in notes
In short
The thousands of biomolecules in a list of living-tissue compounds, amino acids, sugars and the rest, can be called metabolites.
Animal tissues contain the classes of compounds shown for small biomolecules. These are primary metabolites, with identifiable functions in normal physiological processes.
Plant, fungal and microbial cells also hold thousands of further compounds, among them rubber, gums, spices, scents, coloured pigments, essential oils, antibiotics, flavonoids and alkaloids. These are secondary metabolites.
The roles of many secondary metabolites in the organisms that make them are not yet understood, but many are useful to people (rubber, drugs, spices, scents, pigments), and some have ecological importance.
Examples by class: pigments (carotenoids, anthocyanins); alkaloids (morphine, codeine); terpenoids (monoterpenes, diterpenes); essential oils (lemon grass oil); toxins (abrin, ricin); lectins (concanavalin A); drugs (vinblastin, curcumin); polymeric substances (rubber, gums, cellulose).