1. (Biochemistry) the sum total of the chemical processes that occur in living organisms, resulting in growth, production of energy, elimination of waste material, etc. 2. (Biochemistry) the sum total of the chemical processes affecting a particular substance in the body: carbohydrate metabolism; iodine metabolism.
It is found only in cultivation, where it is the most commonly grown of all plants in the Nicotiana genus, and its leaves are commercially grown in many countries to be processed into tobacco.It grows to heights between 1 to 2 metres.he concentration of nicotine increases with the age of the plant. Tobacco leaves contain 2 to 8% nicotine combined as malate or citrate. The distribution of the nicotine in the mature plant is widely variable: 64% of the total nicotine exists in the leaves, 18% in the stem, 13% in the root, and 5% in the flowers.
APPEARANCE: Colorless to pale yellow, oily liquid that turns brown on exposure to air or light. Also available as a powder. DESCRIPTION: Nicotine is a naturally occurring toxic chemical found in tobacco plants. It has a fishy odor when warm. Cigarettes, cigars, other tobacco products, and tobacco smoke contain nicotine. Worker exposure may occur during processing and extraction of tobacco. At one time, nicotine was used in the United States as an insecticide and fumigant; however, it is no longer produced or used in this country for this purpose.