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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).
Cross-sectional view of the structures that can be formed by phospholipids in an aqueous solution. 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.
Conventionally, resting membrane potential can be defined as a relatively stable, ground value of transmembrane voltage in animal and plant cells. Because the membrane permeability for potassium is much higher than that for other ions, and because of the strong chemical gradient for potassium, potassium ions flow from the cytosol out to the ...
In terms of membrane transport the gradient is of interest as it contributes to decreased system entropy in the co-transport of substances against their gradient. One of the most important pumps in animal cells is the sodium potassium pump, that operates through the following mechanism: [9]
The plasma membrane is very specific in its permeability, meaning it carefully controls which substances enter and leave the cell. Because they are attracted to the water content within and outside the cell (or hydrophillic ), the phosphate heads assemble along the outer and inner surfaces of the plasma membrane, and the hydrophobic tails are ...
Where Qp is the permeate stream flowrate [kg·s −1], F w is the water flux rate [kg·m −2 ·s −1] and A is the membrane area [m 2] The permeability (k) [m·s −2 ·bar −1] of a membrane is given by the next equation: = The trans-membrane pressure (TMP) is given by the following expression:
Electroporation, or electropermeabilization, is a technique in which an electrical field is applied to cells in order to increase the permeability of the cell membrane. This may allow chemicals, drugs, electrode arrays or DNA to be introduced into the cell (also called electrotransfer). [1] [2] [3] [4]
The ionic charge determines the sign of the membrane potential contribution. During an action potential, although the membrane potential changes about 100mV, the concentrations of ions inside and outside the cell do not change significantly. They are always very close to their respective concentrations when the membrane is at their resting ...