Movement of substances across the cell membrane

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In the hypertonic and hypotonic solutions, more water molecules repeatedly strike the cell membrane from the side with a high solute concentration, meaning that more water molecules will be forced to pass through the pores of the semi-permeable membrane (Sperelakis, 2001). As a result of this, the water molecules move from the side with high water concentration to the side with a low water concentration until the two sides are equally concentrated. The final solution is called an isotonic solution. Looking at the cell membrane itself, it can be seen that its composition allows for the selective movement of only certain substances. The osmotic pressure in the different cells ensures that the process of osmosis is continued until all the cells in the organism are of equal concentrations. As already mentioned, the semi permeability of the cell membrane allows only for the passage of certain particles, and in the case of the organism, it only allows for the passage of water molecules. This means that the process of osmosis is used to equalize the concentration of solutions in the body cells and their environment. b.Phagocytosis One of the other process by which cell movement is achieved is through phagocytosis, which is the process by which cells engulf foreign particles and ingest them by virtue of their power of amoeboid movement (Sperelakis, 2001). The movement due to phagocytosis is two way, from the point at which the cell moves towards the invading organism to the point when the organism is engulfed into the cell. In most organisms, this process was used for nutrition, but higher organisms have developed it to be used for other functions like fighting disease in the body. In the process, the cell is attracted towards the microbe that needs to be ingested through a process of chemotaxia, which means that the microbe is identified through a chemical signature that attracts the cell. This process is called activation of