Chapter 7: Cellular Structure and Function THE CELL THEORY -All organisims are composed of one or more cells -The cell is the basic unit of structure and organization of organisms -All cells come from pre-existing cells PROKARYOTIC CELL -Simple structure -Contains a plasma membrane -Does not contain membrane bound organelles EUKARYOTIC CELL -Contains a plasma membranre -Contains membrane-bound organelles PLASMA MEMBRANE -Thin, flexible boundary between the cell and its enviornment -Allows nutrients into the cell -Allows waste to leave the cell SELECTIVE PERMEABILITY -The plasma membrane controls the movement of substances into and out of the cell -The plasma membrane is composed of the phospholipid bilayer FLUID MOSAIC MODEL