The Uptake of Sucrose by Bean Leaf Tissue II. Kinetic Experiments

Abstract

Leaf tissue of Phaseolus vulgari8 takes up sucrose from external solutions by two processes. The first is an osmotic uptake into the free space. The second is a non-osmotic uptake into the osmotic volume. The kinetics of the non-osmotic uptake, from solutions less concentrated than 0 ·lM, fit the Michaelis-Menton equation. The tissue can accumulate sucrose against its concentration gradient from solutions less concentrated than 0 ·lM. There is no significant efflux of sucrose from the tissue. The correlation of the rate of carbon dioxide droduction with the internal sucrose concentration suggests that part, at least, of the cytoplasm is included in the osmotic volume for sucrose.