Active transport is the movement of molecules across a cell membrane in the direction against their concentration gradient, i.e. moving from a low concentration to a high concentration. Active transport is usually associated with accumulating high concentrations of molecules that the cell needs, such as ions, glucose and amino acids. If the proces...
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http://en.wikipedia.org/wiki/Active_transport
Movement of a substance across a cell membrane against an electrochemical gradient, in the direction opposite to normal diffusion and requiring the expenditure of energy.
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http://sis.nlm.nih.gov/enviro/iupacglossary/glossarya.html
(from the article `biophysics`) ...laid the groundwork in this subject; his pupil, Hans Ussing, developed the conceptual means by which the transport of ions (charged atoms) across ... ...blood and lymph. In organisms without digestive tracts, substances must also be absorbed in some way from the environment. In some instances ... Th...
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http://www.britannica.com/eb/a-z/a/14
Active transport is the carriage of a solute across a biological membrane from low to high concentration that requires the expenditure of (metabolic) energy.
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http://www.chem.qmul.ac.uk/iupac/medchem/ah.html
Active transport is the carriage of a solute across a biological membrane from low to high concentration that requires the expenditure of (metabolic) energy.
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http://www.chemistry-dictionary.com/definition/active+transport.php
The pumping of individual ions or other molecules across a cell membrane, through the use of a protein, from a region of lower concentration to one of higher concentration. Because the ion or molecule is moved in a direction other than the one in which simple diffusion would take it, this transport ...
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http://www.daviddarling.info/encyclopedia/A/active_transport.html
<biochemistry, chemistry> Transport of ions, nutrients or other molecules into a cell against a concentration gradient, this requires the expenditure of energy through ATP hydrolysis. ... (06 May 1997) ...
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(Life processes and cells) the process by which dissolved molecules (solutes) move across a cell membrane from a lower to a higher concentration
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Often defined as transport up an electrochemical gradient. More precisely defined as unidirectional or vectorial transport produced within a membrane-bound protein complex by coupling an energy-yielding process to a tranport process. In primary active transport systems the transport step is normally coupled to ATP hydrolysis within a single protein `complex'. In secondary active transport the movement of one species is coupled to the movement of …
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Type: Term Definitions: 1. the passage of ions or molecules across a cell membrane, not by passive diffusion but by an energy-consuming process at the expense of catabolic processes proceeding within the cell; in active transport, movement takes place against an electrochemical gradient.
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http://www.medilexicon.com/medicaldictionary.php?t=93362
The movement of molecules or ions across the cell membranes of epithelial cells by membrane carriers. An expenditure of cellular energy (ATP) is required.
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http://www.mhhe.com/biosci/abio/glossary.mhtml
[
n] - transport of a substance (as a protein or drug) across a cell membrane against the concentration gradient
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http://www.webdictionary.co.uk/definition.php?query=active%20transport
noun transport of a substance (as a protein or drug) across a cell membrane against the concentration gradient; requires an expenditure of energy
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https://www.encyclo.co.uk/local/20974
Movement of molecules or ions across a cell membrane using energy provided by respiration. Examples of substances that can be actively transported across membranes are sodium ions and glucose. Energy is needed because the movement occurs against a concentration gradient, with substances being moved f...
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the movement of ions or molecules across a cellular membrane from a lower to a higher concentration, requiring the consumption of energy.
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https://www.infoplease.com/dictionary/active-transport
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