electrochemical gradient

Examples of electrochemical gradient in the following topics:

• Secondary Active Transport

  • In secondary active transport, a molecule is moved down its electrochemical gradient as another is moved up its concentration gradient.
  • Instead, another molecule is moved up its concentration gradient, which generates an electrochemical gradient.
  • The molecule of interest is then transported down the electrochemical gradient.
  • As sodium ion concentrations build outside the plasma membrane because of the action of the primary active transport process, an electrochemical gradient is created.
  • An electrochemical gradient, created by primary active transport, can move other substances against their concentration gradients, a process called co-transport or secondary active transport.

• Electrochemical Gradient

  • The combined gradient of concentration and electrical charge that affects an ion is called its electrochemical gradient .
  • To move substances against a concentration or electrochemical gradient, the cell must use energy.
  • Active transport mechanisms, collectively called pumps, work against electrochemical gradients.
  • Electrochemical gradients arise from the combined effects of concentration gradients and electrical gradients.
  • Define an electrochemical gradient and describe how a cell moves substances against this gradient

• Chemiosmosis and Oxidative Phosphorylation

  • Chemiosmosis is the movement of ions across a selectively permeable membrane, down their electrochemical gradient.
  • The uneven distribution of H+ ions across the membrane establishes both concentration and electrical gradients (thus, an electrochemical gradient) owing to the hydrogen ions' positive charge and their aggregation on one side of the membrane.
  • If the membrane were open to diffusion by the hydrogen ions, the ions would tend to spontaneously diffuse back across into the matrix, driven by their electrochemical gradient.
  • This protein acts as a tiny generator turned by the force of the hydrogen ions diffusing through it, down their electrochemical gradient.
  • ATP synthase is a complex, molecular machine that uses a proton (H+) gradient to form ATP from ADP and inorganic phosphate (Pi).

• Primary Active Transport

  • The sodium-potassium pump maintains the electrochemical gradient of living cells by moving sodium in and potassium out of the cell.
  • One of the most important pumps in animals cells is the sodium-potassium pump (Na+-K+ ATPase), which maintains the electrochemical gradient (and the correct concentrations of Na+ and K+) in living cells.
  • Primary active transport moves ions across a membrane, creating an electrochemical gradient (electrogenic transport).
  • Describe how a cell moves sodium and potassium out of and into the cell against its electrochemical gradient

• ATP in Metabolism

  • In this way, the cell performs work, using energy from ATP to pump ions against their electrochemical gradients.

• Processes of the Light-Dependent Reactions

  • ATP synthase uses this electrochemical gradient to make ATP.

• Transportation of Photosynthates in the Phloem

  • The sucrose is actively transported against its concentration gradient (a process requiring ATP) into the phloem cells using the electrochemical potential of the proton gradient.

• Diffusion

  • On the contrary, concentration gradients are a form of potential energy, dissipated as the gradient is eliminated.
  • Each separate substance in a medium, such as the extracellular fluid, has its own concentration gradient independent of the concentration gradients of other materials.
  • In addition, each substance will diffuse according to that gradient.
  • This lack of a concentration gradient in which there is no net movement of a substance is known as dynamic equilibrium.
  • Extent of the concentration gradient: The greater the difference in concentration, the more rapid the diffusion.

• Transport of Electrolytes across Cell Membranes

  • Water passes through semi-permeable membranes by passive diffusion, moving along a concentration gradient and equalizing the concentration on either side of the membrane.
  • Active transport requires energy in the form of ATP conversion, carrier proteins, or pumps in order to move ions against the concentration gradient.
  • Passive transport, such as diffusion, requires no energy as particles move along their gradient.
  • Active transport requires additional energy as particles move against their gradient.

• Gas Exchange across the Alveoli

  • Since this pressure gradient exists, oxygen can diffuse down its pressure gradient, moving out of the alveoli and entering the blood of the capillaries where O2 binds to hemoglobin.
  • Due to this gradient, CO2 diffuses down its pressure gradient, moving out of the capillaries and entering the alveoli.
  • Oxygen and carbon dioxide move independently of each other; they diffuse down their own pressure gradients.
  • This pressure gradient drives the diffusion of oxygen out of the capillaries and into the tissue cells.
  • The pressure gradient drives CO2 out of tissue cells and into the capillaries.