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.
2. anything resembling an arrow in form, function, or character. 3. a linear figure having a wedge-shaped end, as one used on maps or drawings to indicate direction or placement. v.t. 4. to indicate the proper position of (an insertion) by means of an arrow (often fol. by in).