Search results
Results from the WOW.Com Content Network
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.
Upon striking the sample, photons that match the energy gap of the molecules present (green light in this example) are absorbed, exciting the molecules. Other photons are scattered (not shown here) or transmitted unaffected; if the radiation is in the visible region (400–700 nm), the transmitted light appears as the complementary color (here ...
Transcellular transport often involves energy expenditure whereas paracellular transport is unmediated and passive down a concentration gradient, [4] or by osmosis (for water) and solvent drag for solutes. [5] Paracellular transport also has the benefit that absorption rate is matched to load because it has no transporters that can be saturated.
For quasi-resonant conditions, the energy of the excitation is tuned above the ground state but still below the barrier absorption edge, for example, into the continuum of the first subband. The polarization decay for these conditions is much faster than for resonant excitation and coherent contributions to the quantum well emission are negligible.
Examples of molecules that follow this process are potassium K +, sodium Na +, and calcium Ca 2+. A place in the human body where this occurs is in the intestines with the uptake of glucose . Secondary active transport is when one solute moves down the electrochemical gradient to produce enough energy to force the transport of another solute ...
Schematic of energy levels involved in two photons absorption. In atomic physics, two-photon absorption (TPA or 2PA), also called two-photon excitation or non-linear absorption, is the simultaneous absorption of two photons of identical or different frequencies in order to excite an atom or a molecule from one state (usually the ground state), via a virtual energy level, to a higher energy ...
Electron capture is an example of weak interaction, one of the four fundamental forces. Electron capture is the primary decay mode for isotopes with a relative superabundance of protons in the nucleus , but with insufficient energy difference between the isotope and its prospective daughter (the isobar with one less positive charge ) for the ...
An example of a chloride-bicarbonate antiporter is the chloride anion exchanger, also known as down-regulated in adenoma (protein DRA). It is found in the intestinal mucosa , especially in the columnar epithelium and goblet cells of the apical surface of the membrane, where it carries out the function of chloride and bicarbonate exchange. [ 39 ]