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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 ...
An electrochemical gradient is a gradient of electrochemical potential, usually for an ion that can move across a membrane. The gradient consists of two parts: The chemical gradient, or difference in solute concentration across a membrane. The electrical gradient, or difference in charge across a membrane.
Chemical diffusion occurs in a presence of concentration (or chemical potential) gradient and it results in net transport of mass. This is the process described by the diffusion equation. This is the process described by the diffusion equation.
The grey represents the concentration of a molecule. A biomolecular gradient is established by a difference in the concentration of molecules in a biological system such as individual cells, groups of cells, or an entire organism. A biomolecular gradient can exist intracellularly (within a cell) or extracellularly (between groups of cells).
In cellular biology, active transport is the movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient. Active transport requires cellular energy to achieve this movement.
An ion gradient has potential energy and can be used to power chemical reactions when the ions pass through a channel (red). Hydrogen ions, or protons, will diffuse from a region of high proton concentration to a region of lower proton concentration, and an electrochemical concentration gradient of protons across a membrane can be harnessed to ...
The mechanism of chemotaxis that eukaryotic cells employ is quite different from that in the bacteria E. coli; however, sensing of chemical gradients is still a crucial step in the process. [40] [better source needed] Due to their small size and other biophysical constraints, E. coli cannot directly detect a concentration gradient. [41]
An electrochemical gradient or concentration gradient is a difference in concentration of a chemical molecule or ion in two separate areas. [6] At equilibrium the concentrations of the ion in both areas will be equal, so if there is a difference in concentration the ions will seek to flow "down" the concentration gradient or from a high ...