Membrane Properties

Membrane Properties:Selective Permeability

The phospholipid membrane itself does not allow polar or charged species to flow through it. There are channels, permeases, that allow charged and polar substances entry and exit from the cell.

Oxidative Phosphorylation in Mitochondria

Outer membrane allows passive transport of small molecules through porin (simple channel).

• Inner membrane actively transports protons from the matrix (central area) into the intermembrane space.
• ATPase is associated with a pore forming structure on inner membrane when protons are actively transported out. ATP is consumed when protons are transported out into the intermembrane space.
• However, when the gradient reverses the protons flow in from the intermembrane space into the matrix. This causes the generation of ATP from ADP.

Mechanically Deformable

Membranes can be deformed because they are fluid. Hence fluid-mosaic model. This property comes from the phospholipid bilayer. A membrane is pictured as a mosaic because it has various protein molecules embedded in the phospholipid bilayer .

Communication

Membranes serve in cell-cell communication and signal transduction in the nervous and muscular systems