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Some plants appear not to load phloem by active transport. In these cases, a mechanism known as the polymer trap mechanism was proposed by Robert Turgeon . [ 5 ] In this model, small sugars such as sucrose move into intermediary cells through narrow plasmodesmata, where they are polymerised to raffinose and other larger oligosaccharides .
Polar auxin transport (PAT) is directional and active flow of auxin molecules through the plant tissues. The flow of auxin molecules through the neighboring cells is driven by carriers (type of membrane transport protein) in the cell-to-cell fashion (from one cell to other cell and then to the next one) and the direction of the flow is determined by the localization of the carriers on the ...
Indeed, functional experiments on plant ammonium transporters and Rh proteins suggest a variety of permeation mechanisms including the passive diffusion of NH 3, the antiport of NH 4 + /H +, the transport of NH 4 +, or the cotransport of NH 3 /H +. Lamoureux et al. discuss these mechanisms in light of functional and simulation studies on the ...
In plants, sucrose transport is distributed throughout the plant by the proton-pump where the pump, as discussed above, creates a gradient of protons so that there are many more on one side of the membrane than the other. As the protons diffuse back across the membrane, the free energy liberated by this diffusion is used to co-transport sucrose ...
In cellular biology, membrane transport refers to the collection of mechanisms that regulate the passage of solutes such as ions and small molecules through biological membranes, which are lipid bilayers that contain proteins embedded in them. The regulation of passage through the membrane is due to selective membrane permeability – a ...
An intermediate type of loading exists that uses symplastic transport but utilizes a size-exclusion mechanism to ensure diffusion is a one-way process between the mesophyll and phloem cells. This process is referred to as polymer-trapping, in which simple solutes such as sucrose are synthesized into larger molecules such as stachyose or ...
Phloem (/ ˈ f l oʊ. əm /, FLOH-əm) is the living tissue in vascular plants that transports the soluble organic compounds made during photosynthesis and known as photosynthates, in particular the sugar sucrose, [1] to the rest of the plant. This transport process is called translocation. [2]
The transport mechanism depends on the material being moved. Intracellular transport that requires quick movement will use an actin-myosin mechanism while more specialized functions require microtubules for transport. [5] Microtubules function as tracks in the intracellular transport of membrane-bound vesicles and organelles.