Prokaryotes have only one lipid bilayer- the cell membrane (also known as the plasma membrane). Many prokaryotes also have a cell wall, but the cell wall is composed of proteins or long chain carbohydrates, not lipids.
3. countable noun. A wedge is an object with one pointed edge and one thick edge, which you put under a door to keep it firmly in position. 4. countable noun. A wedge is a piece of metal with a pointed edge which is used for splitting a material such as stone or wood, by being hammered into a crack in the material.
Medical Definition of wedge pressure. : intravascular pressure that is measured by means of a catheter wedged into the pulmonary artery so as to block the flow of blood and that is equivalent to the pressure in the left atriumâcalled also pulmonary capillary wedge pressure, pulmonary wedge pressure.