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Thermodynamically the flow of substances from one compartment to another can occur in the direction of a concentration or electrochemical gradient or against it. If the exchange of substances occurs in the direction of the gradient, that is, in the direction of decreasing potential, there is no requirement for an input of energy from outside the system; if, however, the transport is against ...
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.
A biological membrane, biomembrane or cell membrane is a selectively permeable membrane that separates the interior of a cell from the external environment or creates intracellular compartments by serving as a boundary between one part of the cell and another. Biological membranes, in the form of eukaryotic cell membranes, consist of a ...
An example is the sodium-calcium exchanger or antiporter, which allows three sodium ions into the cell to transport one calcium out. [24] This antiporter mechanism is important within the membranes of cardiac muscle cells in order to keep the calcium concentration in the cytoplasm low. [9]
Illustration of a eukaryotic cell membrane Comparison of a eukaryotic vs. a prokaryotic cell membrane. The cell membrane (also known as the plasma membrane or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of a cell from the outside environment (the extracellular space).
The solute carrier (SLC) group of membrane transport proteins include over 400 members organized into 66 families. [ 1 ] [ 2 ] Most members of the SLC group are located in the cell membrane . The SLC gene nomenclature system was originally proposed by the HUGO Gene Nomenclature Committee ( HGNC ) and is the basis for the official HGNC names of ...
Intracellular transport is unique to eukaryotic cells because they possess organelles enclosed in membranes that need to be mediated for exchange of cargo to take place. [3] Conversely, in prokaryotic cells, there is no need for this specialized transport mechanism because there are no membranous organelles and compartments to traffic between.
Passive diffusion across a cell membrane.. Passive transport is a type of membrane transport that does not require energy to move substances across cell membranes. [1] [2] Instead of using cellular energy, like active transport, [3] passive transport relies on the second law of thermodynamics to drive the movement of substances across cell membranes.