(in biochemistry) an energy-dependent process in which certain substances (including ions, some drugs, and amino acids) are able to cross cell membranes against a concentration gradient. The process is inhibited by substances that interfere with cellular metabolism (e.g. high doses of digitalis).
adj. the ethical distinction between actively doing something to a patient and simply allowing it to happen or failing to act (the acts and omissions doctrine). For instance, doctors should act to save life if possible, but when death is inevitable it is permissible to let it happen, although the prohibition against killing would not allow active intervention. See also dying.... active/passive
a series of enzymes and proteins in living cells through which electrons are transferred, via a series of oxidation-reduction reactions. This ultimately leads to the conversion of chemical energy into a readily usable and storable form. The most important electron transport chain is the respiratory chain, present in mitochondria and functioning in cellular respiration.... electron transport chain
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