Diffusion, Osmosis and Active Transport
Explanation:
The processes of transport between the cell and the external environment can be grouped into groups: Passive Processes - occur through the plasma membrane, without energy expenditure to the cell, to equalize cell concentration with the external medium. Examples of such processes are diffusion, facilitated diffusion and osmosis. Active processes - occur through the plasma membrane, with energy expenditure, maintaining the concentration difference between the cell and the external environment. For example, sodium-potassium pump. Diffusion In diffusion, particles move from the highest concentration medium to the lowest concentration medium, so that it can be distributed throughout the medium. Therefore diffusion is a process called passive transport. Facilitated Diffusion is the passive transport of substances across the plasma membrane, without wasting cell metabolic energy, allowing the passage of substrates (molecules or ions) from a more concentrated to a less concentrated medium through specific mediation of carrier proteins, enzymes carriers or permeases along the plasma membrane. This process is mainly used to transport carbohydrates, amino acids, vitamins and some ions: sodium, potassium, calcium. Osmosis is the name given to the movement of water between media with different concentrations of solutes separated by a semipermeable membrane. It is an important physicochemical process in cell survival.
The sodium-potassium pump is an example of active transport. Sodium concentration is higher in the extracellular environment while potassium is higher in the intracellular environment. Importantly, the energy required for this change comes from the breakdown of the ATP (adenosine triphosphate) molecule into ADP (adenosine diphosphate) and phosphate. The sodium (Na +) ion in the cytoplasm is pumped out of the cell. In the extracellular medium, the potassium ion (K +) is pumped into the internal medium. If there was no efficient active transport, the concentration of these ions would equal. Thus, the sodium and potassium pump is important as it establishes the difference in electrical charge between the two sides of the membrane that is critical for muscle and nerve cells and facilitates the penetration of amino acids and sugars.
