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.
The wedge is an inclined plane used in a different way. Here F is applied horizontally to resist a vertical force W by an inclined interface. In the ideal case, with Î¸ = 45Â°, W = F, and the machine only changes the direction of the force.