temperature Influence. Gradualnye reactions

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Speed of the majority of chemical processes steadily increases with rise in temperature.

Temperature factor Q10 shows, in how many time increases speed of reaction at rise in temperature on 10 ° in comparison with the initial: Q1o for the majority chemical (and including fermentativnyh) reactions equally at least. Whereas for physical processes, such as diffusion or photochemical reactions, Q1o makes nearby 1,1 or 1,2. At the plants which are grown up at temperatures from 0 to 30 °s, with rise in temperature speed vytjagivanija gradually increases and Q10 is equal nearby 2,0 or more (fig. 12.21). On unknown persons to us to the reasons temperature optimum for different plants very strongly differ, and it specifies that any fundamental biochemical process at them possesses various sensitivity to temperature. In a zone above an optimum absolute growth rate at all plants decreases, sometimes very sharply. For bolshej parts of plants this optimum lies in area from 28 to 32 °s.

We do not know, why the majority of plants is damaged by temperatures above approximately 30 °s though enzymes or organelly, allocated of plants, at such temperatures usually are not damaged. One of possible explanations consists that membranes of cages or them organell are sensitive to changes of temperature because of fusion or hardening of fat acids in fosfolipidah. It is known that plants at lower temperatures synthesise more than nonsaturated fats with accordingly lower temperature of fusion.

The Return phenomenon is observed at heats. Other possibility consists that at the raised temperatures any materials necessary for growth, very quickly collapse or are not formed in the necessary quantity. many organisms have genes ' sensitivity to temperature '. At plesnevogo mushroom Neurospora the gene responsible for formation of vitamin В2 (riboflavina), well functions at low temperatures, but does not operate normally at higher. Therefore at 35 °s the mushroom should receive by all means riboflavin from the outside whereas at 25 °s it can grow and for lack of this substance. Business in a similar way could be with other vitamins, amino acids or hormones at the higher plants. if it so, that, knowing a chemical basis of the delay of growth induced in the temperature at supraoptimalnyh temperatures, it would be possible to improve growth by entering of the necessary substances.