Search results
Results from the WOW.Com Content Network
Enantiotopic groups are identical and indistinguishable except in chiral environments. For instance, the CH 2 hydrogens in ethanol (CH 3 CH 2 OH) are normally enantiotopic, but can be made different (diastereotopic) if combined with a chiral center, for instance by conversion to an ester of a chiral carboxylic acid such as lactic acid, or if coordinated to a chiral metal center, or if ...
Donnan equilibrium across a cell membrane (schematic). The Gibbs–Donnan effect (also known as the Donnan's effect, Donnan law, Donnan equilibrium, or Gibbs–Donnan equilibrium) is a name for the behaviour of charged particles near a semi-permeable membrane that sometimes fail to distribute evenly across the two sides of the membrane. [1]
All 11 are necessary for life. The remaining elements are trace elements, of which more than a dozen are thought on the basis of good evidence to be necessary for life. [1] All of the mass of the trace elements put together (less than 10 grams for a human body) do not add up to the body mass of magnesium, the least common of the 11 non-trace ...
One example is [Ru(NH 3) 5 (SMeEt)] 2+. The complex cis-VOCl 2 (SMeEt) 2 exists as meso- and a pair of enantiomers. [7] In complexes of thioethers of the type S(CH 2 R) 2 (R ≠ H), the methylene protons are diastereotopic. Examination of the NMR spectra of such complexes reveal that they undergo inversion at sulfur, without dissociation of the ...
Thomas began writing a monthly essay “Notes of a Biology Watcher” in the New England Journal of Medicine in 1971 while he was at Yale. In 1973 he became the president of the Sloan-Kettering Institute in New York. Lewis Thomas published multiple books throughout his career, the first being The Lives of a Cell: Notes of a Biology Watcher.
For example, the Na + /Ca 2+ exchanger, found in the plasma membrane of many cells, moves three sodium ions in one direction, and one calcium ion in the other. As with sodium in this example, antiporters rely on an established gradient that makes entry of one ion energetically favorable to force the unfavorable movement of a second molecule in ...
An example of a proton pump that is not electrogenic, is the proton/potassium pump of the gastric mucosa which catalyzes a balanced exchange of protons and potassium ions. [citation needed] The combined transmembrane gradient of protons and charges created by proton pumps is called an electrochemical gradient.
2. The cell is the most basic unit of life. Schleiden's theory of free cell formation through crystallization was refuted in the 1850s by Robert Remak, Rudolf Virchow, and Albert Kolliker. [5] In 1855, Rudolf Virchow added the third tenet to cell theory. In Latin, this tenet states Omnis cellula e cellula. This translated to: 3.