By what process can materials move in and out of cells and how are these movements regulated?

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Daniel Williams                03/05/07

Q: By what process can materials move in and out of cells and how are these movements regulated?

The human body is made of many different cells, each of these cells have different structures and carry out different functions to make the body work properly. So from this you can make the assumption that because the cells have different functions and structures the way that materials pass through the cell surface membrane are different to suit each process and cell.

My task is to investigate the ways that cells use, to move materials in and out of the cell surface membrane and look into ways that this movement can take place.  

        The surface of the membrane is designed to allow the passing of materials as it is partially permeable, this means that in the membrane there are pores, which allow smaller molecules through, but not the larger more solute molecules. Also the membrane has intrinsic proteins (which run through both layers of the membrane) and extrinsic proteins (which are situated on the outer layer of the membrane). These are used to transfer none soluble substances in lipids, that would not be able to filter through the partially permeable membrane.

        From research I have discovered four main ways that cells use to move substances in and out of cells for example in transpiration.

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  • Osmosis
  • Diffusion
  • Facilitated diffusion
  • Active transport

Osmosis is the net movement of water molecules from a region of high concentration to a region of low concentration through a partially permeable membrane, which separates the two concentrations. The solvent (e.g. water) will pass from the less concentrated solution to the one of higher until the two concentrations are equal. Once the water molecules are evenly distributed equilibrium occurs. Now the smaller solvent molecules have moved across the membrane they get impeded by the larger solute molecules (e.g. glucose) that are not able to cross the membrane. Because there are ...

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