. Biological transport. Biological transport; Biological Transport. BIOLOGICAL TRANSPORT consequence, these cells may be kept for some time in isotonic glycerol, whereas the human cell is promptly lvsed, for reasons that may be understood from Figure 6. An important spectrophoto- metry method for observation of high rates of solute uptake (0rskov, 1935) depends on the swelling of the cells occasioned by solute entry or exit. The capacity of the human cell to admit glycerol is very high, so that one can show more easily that media- tion occurs by adding an analog, 1,3-propanediol, than by addin
. Biological transport. Biological transport; Biological Transport. BIOLOGICAL TRANSPORT consequence, these cells may be kept for some time in isotonic glycerol, whereas the human cell is promptly lvsed, for reasons that may be understood from Figure 6. An important spectrophoto- metry method for observation of high rates of solute uptake (0rskov, 1935) depends on the swelling of the cells occasioned by solute entry or exit. The capacity of the human cell to admit glycerol is very high, so that one can show more easily that media- tion occurs by adding an analog, 1,3-propanediol, than by adding excess glycerol. This analog has about 100 times as much affinity for the transport site as glycerol does. As an informative point, propanediol itself enters rapidly by other means, so that mediation for its migration is not easily detected. This rapid entry is ascribed to its more lipophilic nature, which presumably permits it to pene- trate the lipid barrier easily. The behavior that has so far been shown for glycerol transport could well arise simply from the presence of a fixed site on the red KC1, KC1, 0A65M + Glycerol, KC1, + Glycerol, 3 M. (a) (b) (c) Figure 6 The swelling of a red cell in isotonic glycerol: (a) The cell has been placed in M glycerol; (b) hypothetical stage at which glycerol has reached a uniform distribution, but no water has yet entered the cell; (c) at this stage water has entered the cell until the internal salts are diluted nearly three times; at this point the cell is ready to burst, but there is still a difference in osmotic pressure, since more glycerol has penetrated with the water. Therefore, water entry will continue. [From Davson, H., and Danielli, J. F., The Permeability of Natural Mem- branes, 2nd ed., Cambridge University Press, Cambridge, 1952, p. 24; with permission.'] 18. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration a
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