v. /trans pawrt", -pohrt"/; n. /trans"pawrt, -pohrt/, v.t.1. to carry, move, or convey from one place to another.2. to carry away by strong emotion; enrapture.3. to send into banishment, esp. to a penal colony.n.4. the act of transporting or conveying; conveyance.5. a means of transporting or conveying, as a truck or bus.6. a ship or plane employed for transporting soldiers, military stores, etc.7. an airplane carrying freight or passengers as part of a transportation system.8. a system of public travel.9. transportation (def. 6).10. strong emotion; ecstatic joy, bliss, etc.11. a convict sent into banishment, esp. to a penal colony: The country had been colonized largely by transports.12. Recording. Also called tape transport. a mechanism that moves magnetic tape past the head in a tape deck or tape recorder.[1325-75; ME transporten (v.) < L transportare to carry across. See TRANS-, PORT5]
* * *In biochemistry, the movement of molecules and particles across a cell membrane, a selective barrier that allows some substances (fat-soluble molecules and some small molecules) to pass and blocks others (ions and large, water-soluble molecules).Transport of these vital substances occurs via several systems. Open channels allow diffusion (passive transport) of ions directly into cells; facilitators use a chemical change to help substances diffuse past the membrane; "pumps" force dilute substances through even when their concentration on the other side is higher (a form of active transport). Primary active transport is powered directly by energy released in cell metabolism (see ATP, adenosine triphosphate). In secondary active transport, a molecule is linked to a different molecule that carries it across the membrane (cotransport) or is exchanged for a different molecule crossing in the other direction (countertransport). The membrane itself opens and closes to let larger particles in or out.
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