membranes

Ch. 7 Membrane Structure and Function Plasma membrane separates living cell from its surroundings Controls traffic into and out of the cell it surrounds Selectively permeable: allows some substances to cross easier than others One of the earliest episodes in the evolution of life may have been the formation of a membrane that enclosed a solution different from the surrounding solution while still permitting the uptake of nutrients and elimination of waste products. Ability of cell to discriminate in chemical exchanges with its environment is fundamental to life Lipids and proteins are the staple of membranes; carbohydrates are also important Phospholipid is amphipathic meaning it has hydrophilic and hydrophobic regions