The movement of solutes along a concentration gradient is common in many biological processes. For a more elaborated discussion, read the Tutorial in Cell Biology where various ways substances pass through a cell membrane are described.
concentration gradient
A regular increase of decrease in the intensity or density of a chemical substance. Cells often maintain concentration gradients of H+ ions across their membranes.
concentration gradient The difference in concentration in two parts of a system.
a concentration gradient (20/0.1 = 200) and a
electrostatic gradient (moving a negative charge against a voltage of − 70 mV).
ΔG = (R)(T) x ln(20/0.1) + (z)(F)(Vm) ...
(Redirected from Concentration gradient)
Jump to: navigation, search
This article is about the physical mechanism of diffusion. For alternative meanings, see diffusion (disambiguation).
Responses to the Concentration Gradient
Coordinate genes such as bicoid lay down the grand plan, so to speak, upon which the genes downstream will act. The pattern of the developing embryo arises as these downstream genes are activated or repressed.
Movement against a concentration gradient requires energy. The energy is supplied by ATP which is released by breaking a phosphate bond to produce ADP:
ATP ® ADP + Pi + energy ...
An ion gradient is a concentration gradient of ions, it can be called an electrochemical potential gradient of ions across membranes. Ionophores are important for ion gradients.
Some of these proteins can move materials across the membrane only when assisted by the concentration gradient, a type of carrier-assisted transport known as facilitated diffusion.
Many times, proteins have to work against a concentration gradient. That term means they are pumping something (usually ions) from areas of lower to higher concentration. This happens a lot in neurons.
Active transport The transport of an ion or a molecule against a concentration gradient, where DG for the transported species is positive; the process must be coupled to an input of free energy from a source such as ATP, ...
Simple diffusion can only move material in the direction of a concentration gradient; facilitated diffusion moves materials with and against a concentration gradient.
C.
active transport 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 ...
Movement of a molecule through a membrane against its concentration gradient, using a carrier protein and energy from ATP
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z ...
Phosphorylation of ADP to ATP occurring when protons that are following a concentration gradient contact ATP synthase.
Was this definition helpful?
Would you have liked more information?
passive transport (facilitated diffusion) - movement of a molecule across a membrane down its concentration gradient
peripheral membrane proteins-proteins that can be released from the membrane ...
energy-expanding process in which cells transport materials across the cell membrane against a concentration gradient.
Source: User Submission
...
Energy in the form of ATP is required when the cell is pumping molecules in or out against the concentration gradient. This is called active transport.
 See also: Membrane, Trans, Ion gradient, Protein, Cell
|
