. The chemical activities of bacteria. Bacteria. 66 THE POEMATION OF ENZYMES IN BACTERIA enzyme may further depend upon the presence of the substrate. The mechanism of adaptation may be that the gene controls the formation of an inactive enzyme-precursor which is only activated by the presence of the substrate; alternatively, it may be that the enzyme is formed in the presence of the gene but is itself unstable in the absence of its substrate. SELECTION. + = present - = absent during growth ADAPTATION Fig. 1. Diagram to illustrate the difference between adaptation and selection processes in en
. The chemical activities of bacteria. Bacteria. 66 THE POEMATION OF ENZYMES IN BACTERIA enzyme may further depend upon the presence of the substrate. The mechanism of adaptation may be that the gene controls the formation of an inactive enzyme-precursor which is only activated by the presence of the substrate; alternatively, it may be that the enzyme is formed in the presence of the gene but is itself unstable in the absence of its substrate. SELECTION. + = present - = absent during growth ADAPTATION Fig. 1. Diagram to illustrate the difference between adaptation and selection processes in enzyme formation. The presence of substances other than the substrate Adaptation involves a relation between the organism, the enzyme, and the substrate, but sometimes substances other than the specific substrate may play a part in the formation or activity of an enzyme. The most marked example of this is found when fermentable carbohydrate is added to the medium. This problem has been studied chiefly with respect to the effect of the presence of glucose during growth on the production of enzymes concerned in the breakdown of proteins. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Gale, E. F. (Ernest Frederick). New York, Academic Press
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectbacteria
