concentration gradient

(noun)

A concentration gradient is present when a membrane separates two different concentrations of molecules.

Related Terms

  • permeable
  • passive transport
  • diffusion

Examples of concentration 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.
  • 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.
    • 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.
    • Diffusion through a permeable membrane moves a substance from an area of high concentration (extracellular fluid, in this case) down its concentration gradient (into the cytoplasm).
  • Osmosis

    • Osmosis is the movement of water through a semipermeable membrane according to the concentration gradient of water across the membrane, which is inversely proportional to the concentration of solutes.
    • Water has a concentration gradient in this system.
    • Thus, water will diffuse down its concentration gradient, crossing the membrane to the side where it is less concentrated.
    • This diffusion of water through the membrane—osmosis—will continue until the concentration gradient of water goes to zero or until the hydrostatic pressure of the water balances the osmotic pressure.
    • Describe the process of osmosis and explain how concentration gradient affects osmosis
  • The Role of Passive Transport

    • In passive transport, substances move from an area of higher concentration to an area of lower concentration .
    • A physical space in which there is a range of concentrations of a single substance is said to have a concentration gradient.
    • In solutions containing more than one substance, each type of molecule diffuses according to its own concentration gradient, independent of the diffusion of other substances.
    • Many factors can affect the rate of diffusion, including, but not limited to, concentration gradient, size of the particles that are diffusing, and temperature of the system.
    • Diffusion through a permeable membrane moves a substance from an area of high concentration (extracellular fluid, in this case) down its concentration gradient (into the cytoplasm).
  • Electrochemical Gradient

    • Simple concentration gradients are differential concentrations of a substance across a space or a membrane, but in living systems, gradients are more complex.
    • The electrical gradient of K+, a positive ion, also tends to drive it into the cell, but the concentration gradient of K+ tends to drive K+ out of the cell.
    • 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.
    • Electrochemical gradients arise from the combined effects of concentration gradients and electrical gradients.
  • Transport of Electrolytes across Cell Membranes

    • Osmotic pressure is influenced by the concentration of solutes in a solution.
    • 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.
  • Principles of Electricity

    • Diffusion arises from the statistical tendency of particles to redistribute from regions where they are highly concentrated to regions where the concentration is low .
    • Differences in concentration of ions on opposite sides of a cellular membrane lead to a voltage called the membrane potential.
    • Many ions have a concentration gradient across the membrane, including potassium (K+), which is at a high inside and a low concentration outside the membrane.
    • Sodium (Na+) and chloride (Cl–) ions are at high concentrations in the extracellular region, and low concentrations in the intracellular regions.
    • These concentration gradients provide the potential energy to drive the formation of the membrane potential.
  • Diffusion

    • Diffusion is the movement of particles from regions of high concentration towards regions of lower concentration.
    • Diffusion is the movement of particles move from an area of high concentration to an area of low concentration until equilibrium is reached .
    • Diffusion explains the net flux of molecules from a region of higher concentration to one of lower concentration.
    • However, diffusion can still occur in the absence of a concentration gradient.
    • Particles moving from areas of high concentration to areas of low concentration.
  • 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.
    • This protein acts as a tiny generator turned by the force of the hydrogen ions diffusing through it, down their electrochemical gradient.
    • In oxidative phosphorylation, the hydrogen ion gradient formed by the electron transport chain is used by ATP synthase to form ATP.
    • ATP synthase is a complex, molecular machine that uses a proton (H+) gradient to form ATP from ADP and inorganic phosphate (Pi).
  • Proton Reduction

    • Anaerobic respiration utilizes highly reduced species - such as a proton gradient - to establish electrochemical membrane gradients.
    • An electrochemical gradient has two components.
    • Second, a chemical component is caused by a differential concentration of ions across the membrane.
    • Cellular respiration (both aerobic and anaerobic) utilizes highly reduced species such as NADH and FADH2 to establish an electrochemical gradient (often a proton gradient) across a membrane, resulting in an electrical potential or ion concentration difference across the membrane.
    • In contrast, fermentation does not utilize an electrochemical gradient.
Subjects
  • Accounting
  • Algebra
  • Art History
  • Biology
  • Business
  • Calculus
  • Chemistry
  • Communications
  • Economics
  • Finance
  • Management
  • Marketing
  • Microbiology
  • Physics
  • Physiology
  • Political Science
  • Psychology
  • Sociology
  • Statistics
  • U.S. History
  • World History
  • Writing

Except where noted, content and user contributions on this site are licensed under CC BY-SA 4.0 with attribution required.