the Mechanism floemnogo transport. Loading floemy

you are: the Mechanism floemnogo transport

In leaves sucrose, a primary mobile product of photosynthesis, should arrive in sitovidnye tubes against a concentration gradient. That sheet veins vetvjatsja repeatedly until diameter of their terminations does not appear equal to a thickness of several vessels and sitovidnyh tubes is remarkable. in this place they closely adjoin to mezofilnym to the cages taking active part in photosynthesis. At a sugar beet (Beta vulgaris) sucrose is pumped up in these trailer tubes directly from walls of surrounding cages mezofilla and small mezhkletnikov where it at first is transported from cages mezofilla (fig. 8.6). Transport of sucrose in floemu is selective and interfaced to an active metabolism. Possibly, thus there is a joint penetration (to-traneport) sucrose and hydrogen (N +) through specific permeazu, present in plazmalemme sitovidnyh tubes, thanks to a gradient rn and to an electrochemical gradient. Later at unloading energy is necessary for pumping out of ions of hydrogen from sitovidnyh tubes by means of the ATR-DEPENDENT carrier of ions N +. This enzyme uses for moving of ions N + through a membrane the energy liberated at hydrolysis ATR. Ions of hydrogen then can diffundirovat back in a cage together with sucrose, using specific protonno-saccharose permeazu and moving on an electrochemical gradient of ions N +.