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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).

Active transport 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 is provided by the coupled hydrolysis of ATP or the cotransport of another molecule down its electrochemical gradient.

active transport
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.

Active 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.

~ 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
beating of cilia and flagella (including sperm) ...

~ 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 ...

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).
adenosine diphosphate (ADP) a product of adenosine triphosphate (ATP) breakdown.

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
Involves ATP by cells (mitochondria) / respiration ...

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 ...

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. This allows cells to take up essential molecules even when they are at a low concentration outside.

~ 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.

~ - 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
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~ involves the movement of substances through the membrane using energy from ATP. The advantage of active transport is that substances can be moved against the concentration gradient, meaning from a region of low concentration to a region of high concentration.

~ the movement of substances from where they are less concentrated to where they are more concentrated (against a concentration gradient)
Adaptation any feature of the structure or physiology of an organism that makes it well suited to its environment.

~ 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.

~ works to maintain or increase the concentration gradient of a substance between two regions while passive transport acts in a manner to reduce the concentration gradient.
14. What are the three main types of passive transport?

~ - 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 ...

Whereas active transport does require that the cells spend some energy in order to get material into the cell or toss it out of the cell. And again that is usually in the form of ATP, now those of you who have taken Physics know to move something generally it does take some energy.

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.

~ of these ions must occur. Specific carrier proteins in the plasma membrane attract and carry their specific mineral into the cell. A Proton Pump: H+ is pumped out of the cell causing a change in pH and a voltage across the membrane.

The ~ of Na+ and solute molecules depends on the proton electrochemical gradients established by proton pumps.

PS is normally sequestered in the inner leaflet of the plasma membrane bilayer by an active transporter, 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 active transport 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: What is the meaning of Trans, Membrane, Protein, Cell, Molecule?

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