How does the process of diffusion take place across the cell membrane?
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Solution
Diffusion:
Diffusion can be defined as the random or spontaneous movement of molecules (like carbon dioxide and oxygen) from the region of higher concentration to the region of lower concentration.
The movement of molecules from the region of higher concentration to the region of lower concentration continues until both concentrations become equal.
Diffusion is an important process that is responsible for the exchange of gases in and out of the cells as well as their environment.
For example, when the concentration of carbon dioxide is higher inside the cell than in its external environment, it is released out of the cell by diffusion. Similarly, oxygen enters the cell when its concentration is less inside the cell compared to that of the external environment by diffusion.
Diffusion is divided into two types namely, simple diffusion and facilitated diffusion.
In simple diffusion, the transportation of molecules across the membrane takes place without the help of any transport proteins or carriers. During this process, the molecules pass through the phospholipid bilayer and get dissolved into the aqueous solution on the opposite side.
Facilitated diffusion is a type of passive transport in which molecules move across the membrane with the help of specific transmembrane integral proteins (proteins that facilitate the movement of molecules across the cell membrane). Facilitated diffusion is a selective process i.e. it allows only selective molecules or ions to pass through the channels formed by the proteins.
