| Abstrakt: |
The permeability of the internodal cells of Nitella mucronata to 70 nonclectrolytes has been determined by quantitative chemical analyses of the amounts taken up or given off by single cells at 20°C. in definite intervals under the influence of a concentration gradient of known magnitude. The permeability of the protoplast alone has also been calculated. The permeation power towards Nitella protoplasts is found to be roughly proportional to the 1.3rd power of the partition coefficient in the system ether/water or. still more closely, to about the same power of the olive oil/water partition coefficient. On the other hand, it is inversely proportional lo about the 1.5th power of the molecular weight. The permeation power of the smallest molecules is, however, greater than these statements would imply. The permeability properties of Chara and Nitellopsis are on the whole very similar to those of Nitella, except for one consistent difference: the P-values for Nitellopsis are approximately proportional to (kolive oil)1.15 those for Chara to the oil/water partition coefficient itself. These permeability differences are probably due to differences in the degree of hydrophobia of the plasma membrane lipoids. [ABSTRACT FROM AUTHOR] |
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