Search results
Results From The WOW.Com Content Network
The breakdown of these larger macromolecules is critical for allowing their constituents to pass through the cell membrane and enter into the cell. For humans and other complex organisms, this process is best characterized by the digestive system which breaks down solid food [1] via exoenzymes. The small molecules, generated by the exoenzyme ...
Exoenzymes also aid digestion in the guts of ruminants, [6] termites, [7] humans and herbivores. By hydrolyzing plant cell wall polymers, microbes release energy that has the potential to be used by humans as biofuel. [8] Other human uses include waste water treatment, [9] composting [10] and bioethanol production. [11]
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).
Cell theory has its origins in seventeenth century microscopy observations, but it was nearly two hundred years before a complete cell membrane theory was developed to explain what separates cells from the outside world. By the 19th century it was accepted that some form of semi-permeable barrier must exist around a cell.
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.
Exocytosis and its counterpart, endocytosis, are used by all cells because most chemical substances important to them are large polar molecules that cannot pass through the hydrophobic portion of the cell membrane by passive means. Exocytosis is the process by which a large amount of molecules are released; thus it is a form of bulk transport.
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 ...
It eliminated the need to accommodate membrane proteins in thin surface layers, proposed that the variability in the protein/lipid ratios of different membranes simply means that different membranes vary in the amount of protein they contain, and showed how the exposure of lipid-head groups at the membrane surface is compatible with their ...