MEMBRANES

•They regulate the passage of molecules into and out of cells and organelles .•They divide the cell into numerous compartments, each with its own specialize metabolism.•They act as surfaces that hold enzymes.

COMPOSITION OF MEMBRANES

•All biological membranes are composed of proteins and two layers of phospholipid molicules.

2 kinds of Proteins

1. Intrinsic proteins = proteins that are eve partially immersed in the lipid bilayer.2. extrinsic proteins (Peripheral proteins) = are located outside the membrane, and merely lie next to it.

Properties of Membranes•They can grow•Permeability *Selectively Permeable(Differentially permeable) = means that certain substances cross the membranes more easily and rapidly than others. *Freely Permeable membrane = allows everything to pass through quickly. *Impermeable Membrane = does not allow anything to pass through at all.•They are dynamic, constantly changing. As the nature of the membrane changes, the nature of the cell changes also.

MEMBRANES