For the following modes of transport for membranes, tell whether the flow is with or against chemical potenial. Meaning +deltaG or -deltag A. Passive Diffusion B.Faciliated Diffusion C.Active Transport
For the following modes of transport for membranes, tell whether the flow is with or against chemical potenial. Meaning +deltaG or -deltag
A. Passive Diffusion
B.Faciliated Diffusion
C.Active Transport
Introduction:
The term cell membrane is used synonymously with the plasma membrane. It is 7 to 10 nm thick. The cell membrane structure is well described by the fluid mosaic model, which mentions that all the membranes comprise a double layer of lipid molecules in which proteins are embedded. These proteins are of two types, lipoproteins and glycoproteins. Some proteins are located on the inner side of the membrane (intrinsic proteins), and some are located on the external surface of the membrane (peripheral and extrinsic proteins). At the same time, some extend through the membrane (transmembrane proteins).
One of the most important features of the plasma membrane is the property of selective permeability:
- Non-polar molecules like gases (oxygen, carbon dioxide), steroid hormones, lipids, and alcohol can dissolve in the non-polar regions of the membrane and thus move rapidly across the membrane. On the other hand, polar molecules like water-soluble substances (glucose, ions, urea) have much lower solubility and penetrate the membrane much more slowly.
- The chemical and physical characteristic of membrane controls the free passage of ions and molecules into and out of the cell. This property of selective permeability of cell membrane helps maintain the difference of composition between extracellular and intracellular fluid.
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