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Active transport

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Active transport
From Wikipedia, the free encyclopedia
Active transport is the movement of a substance against its concentration gradient (from low to high concentration).


is the mediated transport of biochemicals, and other atomic/molecular substances, across membranes. Unlike passive transport, this process requires chemical energy.

active transport
Energy-requiring movement of an ion or small molecule across a membrane against its concentration gradient or electrochemical gradient.


energy-expanding process in which cells transport materials across the cell membrane against a concentration gradient.
Source: User Submission ...

Active transport is important so that substances can move in and out of a cell across the selectively permeable cell membrane against a concentration gradient.
Compare: passive transport, diffusion.
See also: concentration gradient.

- ENERGY TO TRANSPORT
describes what happens when a cell uses energy to transport something. We're not talking about phagocytosis (cell eating) or pinocytosis (cell drinking) in this section.

active transport of molecules and ions
nerve impulses
maintenance of cell volume by osmosis
adding phosphate groups (phosphorylation) to many different proteins, e.g., to alter their activity in cell signaling.
muscle contraction ...

Transport of molecules against a concentration gradient (from regions of low concentration to regions of high concentration) with the aid of proteins in the cell membrane and energy from ATP. PICTURE ...

active transport
The movement of a substance across a biological membrane against its concentration or electrochemical gradient, with the help of energy input and specific transport proteins.
adaptation ...

the movement of molecules across a membrane from a region of low concentration to a region of high concentration that requires the expenditure of energy (ATP).

Active Transport
Movement of solute against the conc. gradient, from low to high conc.
Involves materials which will not move directly through the bilayer
Molecules bind to specific carrier proteins / intrinsic proteins ...


Movement across membrane with an energy cost (usually against concentration or electrochemical gradient, but not always)
Used to pump specific compounds in or out of the cell ...

Active transport
Sometimes substances need to be moved from where they are at a lower concentration to where they are at a higher concentration - against the concentration gradient.

The transport by a carrier protein of a molecule through a plasma-membrane against its concentration or electrochemical gradient.
Online Biology Dictionary (ACU-)
aculeolate /ak-yə-LEE-ə-lət/ Having tiny prickles.

Active transport involves the use of energy supplied by the cell to move materials across the membrane against a concentration gradient. Transport proteins are used and energy is supplied by ATP.
Diffusion ...

- The transport of molecules across a membrane and against their natural flow; mediated by carrier proteins and requiring outside energy.

[edit] Active transport
Primary active transport
Transport proteins are also used in active transport, which by definition does require an energy input.


The Southwest Environmental Health Sciences Center
The Biology Project
The University of Arizona
Monday, February 22, 1999
Contact the Development Team ...

Active transport involves the movement of substances through the membrane using energy from ATP.

the movement of substances from where they are less concentrated to where they are more concentrated (against a concentration gradient) ...

active transport A process that requires an expenditure of ATP energy to move molecules across a cell membrane; usually moved against the concentration gradient with the aid of specific transport proteins.

- movement of a molecule across a membrane or other barrier driven by energy other than that stored in the concentration gradient or electrochemical gradient of the transported molecule ...

Active transport requires the cell to spend energy, usually in the form of ATP. Examples include transport of large molecules (non-lipid soluble) and the sodium-potassium pump.

Whereas does require that the cells spend some energy in order to get material into the cell or toss it out of the cell.

ATP can power active transport by transferring a phosphate group from ATP (forming ADP) to the transport protein.
This may induce a conformational change in the transport protein, translocating the solute across the membrane.

PS is normally sequestered in the inner leaflet of the plasma membrane bilayer by an er, the aminophospholipid translocase (APLT).

Part of the pressure-flow theory is that the sucrose produced is moved by active transport into the companion cells of the phloem in leaf veins.

Many of the proteins play a role in the selective transport of certain substances across the phospholipid bilayer, either acting as channels or molecules.

This is done by a selective process involving active transport and the utilization of a lot of ATP. Nutrients are reabsorbed by the cells lining the nephron and water is reabsorbed as needed. Waste products such as urea are not reabsorbed.

See also: See also: Trans, Membrane, Cell, Protein, Molecule

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