Question

Q1 describe the permeability of lipid membranes? what are the relative permeability of different substances?

this question is essential biology 4th edition chapter 12

Answer 1

Plasma membrane is a dynamic, fluid structure and form the external boundary of cells . It acts as a selectively permeable membrane and regulates the molecular traffic across the boundary. It exhibits selective permeability; that is, it allows some sort of you to cross it more easily than others. It forms a barrier that blocks the free exchange of molecules between the cytoplasm and the external environment of the cell. Small molecules such as O2, and CO2, readily dissolve in lipid bilayer therefore diffuse rapidly across them.

The relative permeability of different classes of molecules across lipid bilayer- violin is permeable to small hydrophobic molecules and a small uncharged polar molecules, slightly permeable to water and urea, and essentially impermeable to ions.