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.
1 A wedge. 2  A thin piece of material, sometimes tapered, used for alignment or support. ( 3 computing) A small library that transparently intercepts and modifies calls to an API, usually for compatibility purposes.  A kind of shallow plow used in tillage to break the ground and clear it of weeds.