5.3 Active Transport

5.3 Active Transport

  • If the substance's concentration inside the cell is greater than its concentration in the fluid, the cell must use energy to move it.
    • Some active transport mechanisms move small-molecular weight materials.
  • In living systems, the concentration of a substance is more complex than it is in a space.
    • The cells have higher concentrations of K+) and lower concentrations of Na+) than the fluid in which they are bathed.
    • In a living cell, the concentration of Na+ tends to drive it into the cell, and the electrical gradient also drives it into the negatively charged interior.
    • The situation for other elements is more complicated.
    • The concentration of K+ drives K+ out of the cell, but the electrical gradient of K+ drives it into the cell.
  • Concentration and electrical gradients have an effect on chemical gradients.
    • There are structures labeled A.
  • It's lethal to inject a solution into a person's blood.
    • This is how capital punishment ends.
  • The cell uses energy to move substances.
    • The energy comes from the cell's metabolism.
  • Small substances pass through the blood stream.
    • Active transport maintains concentrations of ion and other substances that living cells need.
    • A cell may use a lot of its energy supply.
    • Because active transport mechanisms depend on a cell's metabolism for energy, they are sensitive to many metabolic poisons.
  • There are two mechanisms for transporting small-molecular weight material.
  • All of the transporters can carry small, un charged organic molecules.
  • Some examples of pumps for active transport are Na+-K+ATPase and H+-K+ATPase.
    • Both of these are antiporter carriers.
    • Two of the carrier proteins are Ca2+ and H+, which only carry calcium and hydrogen.
    • Both of them are pumps.
  • A uniporter carries something.
    • A symporter carries two different things in the same direction.
    • An antiporter carries two different things in different directions.
    • Secondary active transport can occur if the primary active transport is functioning.
    • The second transport method depends on using energy and is still active.
  • The primary active transport moves the ion across the membrane.
  • The correct concentrations of Na+ and K+) in living cells are maintained by the sodium-potassium pump.
    • The pump moves K+ into the cell while moving Na+ out at the same time, at a ratio of three Na+ for every two K+ ion moved in.
    • The Na+-K+ATPase can be found in two different forms, depending on its orientation to the cell's interior or exterior.
    • There are six steps in the process.
  • The carrier has a high affinity for sodium ion.
    • There are three ion bind to the protein.
  • There is a low-energy phosphate group attached to it.
  • The three sodium ion leave the carrier when the protein's affinity for sodium decreases.
  • The shape change increases the carrier's affinity for the potassium ion.
    • The low-energy group detaches from the carrier.
  • The carrierProtein has a decreased affinity for potassium and the two ion move into the cytoplasm.
    • The process starts again after the protein has a higher affinity for sodium ion.
  • There are a number of things that have happened as a result of this process.
    • At this point, there are more sodium ion outside the cell than inside.
    • Two potassium ion move in for every three sodium ion that leaves.
    • The interior is slightly more negative than the exterior.
    • The conditions needed for the secondary process are created by the difference in charge.
  • You can watch the video to see an active transport simulation.
  • Secondary active transport brings compounds into the cell.
    • The primary active transport process creates an electrochemical gradient when the concentration of sodium ion builds outside of the plasma membrane.
    • The sodium ion will pull through the membrane if the channel is open.
    • The movement transports substances that can attach themselves to the transport protein.
    • This is the way in which many acids and sugars enter a cell.
    • The secondary process stores high-energy hydrogen ion in the cells of plants and animals.
    • The potential energy that accumulates in the hydrogen ion is translated into energy by the ion surge through the channel.
  • A process scientists call co-transport or secondary active transport is when primary active transport creates an electrochemical gradient that can move other substances against their concentration gradients.