dissimilation in biology

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DISSIMILATION in biology (Latin dissimilis dissimilar) — process of disintegration of organic compounds (proteins, fats, carbohydrates, etc.) on simple substances; anti-on false process of assimilation. The unity of processes of D. and assimilation provides the metabolism and energy which is the cornerstone of life activity of animal and vegetable organisms, continuity of updating of organic matter throughout all life of an organism (see. Assimilation ).

Dissimilation at plants

takes the Central place in a metabolism a number of processes — breath (see), fermentation (see) and glycolysis (see). Release of the energy concluded in molecules of complex organic compounds and used is result of these processes then at implementation of vital signs. The key end products of D. in all organisms — water, carbon dioxide gas and ammonia. If at animals these products in process of accumulation are allocated outside, then at plants carbon dioxide gas partially, and ammonia are completely used for biosynthesis of organic matters, being, thus, a starting material for assimilation.

Intensity of processes of D. at plants changes depending on a stage of an ontogeny of an organism and depends on activity of enzymes, participation of the phytohormones and other connections necessary for growth and development of plants. Under unfavorable conditions — increase or fall of temperature, a drought, diseases, a lack of oxygen, light or mineral connections — D.'s processes amplify.

Sharp dominance of D. over processes of assimilation leads to exhaustion and finally — to death of a plant.

Dissimilation at animals — see. Metabolism and energy .

Bibliography: Kretovich V. L. Fundamentals of phytochemistry, M., 1971; Rubin B. A. both Ladygina M. E. Fiziologiya and biochemistry of breath of plants, M., 1974; Skulachev V. P. Accumulation of energy in a cell, M., 1969, bibliogr.

G. M. Grineva.