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There are two types of active transport: primary active transport that uses adenosine triphosphate (ATP), and secondary active transport that uses an electrochemical gradient. This process is in contrast to passive transport , which allows molecules or ions to move down their concentration gradient, from an area of high concentration to an area ...
Diffusion vs. Transport. In biology, an ion transporter is a transmembrane protein that moves ions (or other small molecules) across a biological membrane to accomplish many different biological functions, including cellular communication, maintaining homeostasis, energy production, etc. [1] There are different types of transporters including pumps, uniporters, antiporters, and symporters.
Facilitated diffusion may occur through three mechanisms: uniport, symport, or antiport. The difference between each mechanism depends on the direction of transport, in which uniport is the only transport not coupled to the transport of another solute. [4] Uniporter carrier proteins work by binding to one molecule or substrate at a time ...
Unlike channel proteins which only transport substances through membranes passively, carrier proteins can transport ions and molecules either passively through facilitated diffusion, or via secondary active transport. [11] A carrier protein is required to move particles from areas of low concentration to areas of high concentration.
The word diffusion derives from the Latin word, diffundere, which means "to spread out". A distinguishing feature of diffusion is that it depends on particle random walk, and results in mixing or mass transport without requiring directed bulk motion. Bulk motion, or bulk flow, is the characteristic of advection. [1]
Secondary active transport is when one solute moves down the electrochemical gradient to produce enough energy to force the transport of another solute from low concentration to high concentration. [ citation needed ] An example of where this occurs is in the movement of glucose within the proximal convoluted tubule (PCT).
The self-diffusion coefficient of neat water is: 2.299·10 −9 m 2 ·s −1 at 25 °C and 1.261·10 −9 m 2 ·s −1 at 4 °C. [ 2 ] Chemical diffusion occurs in a presence of concentration (or chemical potential) gradient and it results in net transport of mass.
Forced diffusion occurs because of the action of some external force; Diffusion can be caused by temperature gradients (thermal diffusion) Diffusion can be caused by differences in chemical potential; This can be compared to Fick's law of diffusion, for a species A in a binary mixture consisting of A and B: