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The glucose transporter (GLUTs) is a type of uniporter responsible for the facilitated diffusion of glucose molecules across cell membranes. [9] Glucose is a vital energy source for most living cells, however, due to its large size, it cannot freely move through the cell membrane. [16]
Tracer diffusion and Self-diffusion, which is a spontaneous mixing of molecules taking place in the absence of concentration (or chemical potential) gradient. This type of diffusion can be followed using isotopic tracers, hence the name. The tracer diffusion is usually assumed to be identical to self-diffusion (assuming no significant isotopic ...
Molecules are transported across an epithelial or endothelial barrier by one of two routes: 1) a transcellular route through the intracellular compartment of the cell, or 2) a paracellular route through the extracellular space between adjacent cells. [18] The transcellular route is also called transcytosis.
Fick's first law relates the diffusive flux to the gradient of the concentration. It postulates that the flux goes from regions of high concentration to regions of low concentration, with a magnitude that is proportional to the concentration gradient (spatial derivative), or in simplistic terms the concept that a solute will move from a region of high concentration to a region of low ...
A membrane transport protein is a membrane protein involved in the movement of ions, small molecules, and macromolecules, such as another protein, across a biological membrane. Transport proteins are integral transmembrane proteins ; that is they exist permanently within and span the membrane across which they transport substances.
Diffusion is the first and most important mechanism that allows the flow of small molecules across capillaries. The process depends on the difference of gradients between the interstitium and blood, with molecules moving to low concentrated spaces from high concentrated ones. [ 8 ]
The permeases are membrane transport proteins, a class of multipass transmembrane proteins that allow the diffusion of a specific molecule in or out of the cell in the direction of a concentration gradient, a form of facilitated diffusion. [1] The permease binding is the first step of translocation.
Crane in 1961 was the first to formulate the cotransport concept to explain active transport. Specifically, he proposed that the accumulation of glucose in the intestinal epithelium across the brush border membrane was [is] coupled to downhill Na+ transport cross the brush border. This hypothesis was rapidly tested, refined, and extended [to ...