Biological Membranes

Abstract

Membranes are much more than the physical boundary of each cell. In eukaryotic (nucleated) cells, the different cellular organelles, such as the chloroplasts and mitochondria, are made of elaborate membrane structures. The membranes of different organelles and cells each have a characteristic structure and function. Wherever they occur, membranes are the site of a good deal of the activity of the cell and it is part of the purpose of this chapter to give an outline of some of the ideas concerned with the relationship between membrane structure and function. There are a number of functions associated particularly with membranes; these include the rather obvious need to keep materials in or out of the cells and at the same time to allow the passage of certain substances through selectively. Membranes in certain parts of cells are also important as the sites of energyproducing activities.