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.
Also called wedge. 4. A long, narrow, or crested part of the body: the ridge of the nose. 5. The horizontal line formed by the juncture of two sloping planes, especially the line formed by the surfaces at the top of a roof. 6. A narrow, raised strip, as in cloth or on plowed ground.