Question

How does the rate of diffusion vary with the solubility in lipids?

Answer 1

Diffusion:

1. The movement of molecules of any substance from high concentration to low concentration through a semi-permeable membrane is called diffusion.
2. Diffusion does not require energy (in the form of ATP).
3. The rate of diffusion is affected by many factors like pressure and temperature.
4. In the biological system, plasma membrane of a cell acts as a selective membrane.
5. Here, the diffusion of molecules into and out of the cell depends on the solubility of these molecules in lipids.
6. As we know, the cell membrane is made up of a phospho-lipid bilayer.
7. So, the molecules which are soluble in lipids can diffuse easily across the cell membrane.
8. Some molecules are hydrophilic and not soluble in lipids. Therefore, they do not diffuse easily across the cell membrane and require the involvement of specialized proteins for their transport.