Cellular Transport
Cellular Transport
Osmosis is the flow of water through a semi permeable membrane that blocks the transport of salts or other solutes through it. It is also defined as the net movement of water from an area of high concentration to a region of low concentration. Osmosis is a fundamental effect in all biological systems. When two water volumes are separated by a semi permeable membrane water will flow from the side of low solute concentration to the side of high solute concentration. If external pressure is applied on the area of high concentration then reverse osmosis may occur. The movement of solute molecules within a solvent is determined by the solvent molecules that surround it. Collisions of solute molecules determine movement. For example, in a u-tube, the two vessels are separated by a semi permeable membrane. The system will stabilize when the osmotic pressure is balanced. The solute molecules generate pressure on all solution boundaries, including the membrane. Osmosis is significant is plant and animal cells. In a plant cell, the water moves to the vacuole. In a hyperosmotic solution, that is, there is a lower concentration of water, if water permeates out of an animal cell, the cell becomes crenated or shriveled. In an isosmotic solution (equal concentrations) water enters and leaves the cell sufficiently, allowing the call to function properly. In a hypoosmotic solution (higher water concentration) the cell becomes lysed as too much water enters the call. When a plant cell is in a hyperosmotic solution, water leaves the cell and it becomes plasmolyzed. In an isosmotic solution, the flow of water in and out of the plant call is flaccid. In a hypoosmotic solution, the large amount of water that enters the cell causes to become turgid. Osmosis is a significant inn the functioning of cells.
Another essential type of cellular transport is facilitated diffusion. Defined as the net movement of molecules, ions and atoms from a region of high concentration to low. All particles are constantly in motion, henceforth diffusion involves the movement of particles. Diffusion results from the random motion and/or collisions of particles. It is the act measured of particles as a result of a concentration gradient, where concentration is the number of particles per unit volume and concentration gradiet is a difference in concentration of a substance across a space. Diffusion will continue until the particles become uniformly distributed in the...