Types+of+material+transport+for+cells

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**Diffusion:** Diffusion in basic terms is the passive movement of molecules along a concentration gradient from an area of high concentration to low concentration and the molecules are 'spread' evenly throughout the space, achieving equilibrium. On expanding this knowledge diffusion is the random movement of molecules by the use of kinetic energy, the molecules may bump into each other, the wall or pass through the pores of the membrane and onto the side where there is usually less amounts of that molecule, if more molecules move from one side to the other than the other way around this is known as **net diffusion.** The process of diffusion is spontaneous but considering that some cell membranes are selectively permeable (which means that they only allow certain substances to enter the cell) it may take longer for some molecules/particles to diffuse.


 * Facilitated Diffusion: **This type of diffusion does not require ATP (energy) but it does require cell membrane channel proteins also known as carrier proteins, to bring molecules across the cell membrane from higher concentrated area to a lower concentratio n.  Through the use of channel proteins and carrier proteins that are embedded in the cell membrane substances can be transported into the cell. Ion channel proteins allow specific ions to pass through the protein channel. The ion channels are regulated by the cell and are either open or closed to control the passage of substances into the cell. Carrier proteins bind to specific molecules, change shape and then deposit the molecules across the membrane. Once this has occurred the proteins return to their original position.



In osmosis water diffuses from a hypotonic (low solute concentrated) solution to a hypertonic (high solute concentrated) solution, the direction of water flow is osmosis determined by the solute concentration. "If a molecule, lets say a blood cell was placed in salt water solutions of different concentrations, the following will occur: > >
 * Osmosis:** Osmosis is a special type of material transport in cells as it is the diffusion and transportation of water rather than the transportation of molecules such as glucose.
 * If the salt water solution is **hypertonic** it would contain a higher concentration of solute and a lower concentration of water than the blood cells. Fluid would flow from the area of low solute concentration (the blood cells) to an area of high solute concentration (water solution). As a result the blood cells will shrink.
 * If the salt water solution is **isotonic** it would contain the same concentration of solute as the blood cells. Fluid would flow equally between the blood cells and the water solution. As a result the blood cells will remain the same size.
 * If the salt water solution is **hypotonic** it would contain a lower concentration of solute and a higher concentration of water than the blood cells. Fluid would flow from the area of low solute concentration (water solution) to an area of high solute concentration (the blood cells). As a result the blood cells will swell and even burst." - biologyabout.com

 


 * Active Transport:** Is the transportation of molecules through the cell membrane by using energy or Adenosine Triphosphate and going //against// the concentration gradient meaning they go from an area of low concentration to an area of high concentration. A molecule or ion attaches itself to a carrier molecule, the carrier delivers the molecule to the correct destination. This process uses up 40 percent of the cells energy. If the molecule is too big to enter the cell via active transport it can enter by endocytosis using ATP; the molecules and particles enter the cell in a vesicle which is formed by an indentation of the cell membrane. It can also enter the cell by exocytosis which is when the golgi apparatus synthesize and store vesicles containing molecules for export through this process.