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.
Tax Wedge. What is a 'Tax Wedge'. A tax wedge is the difference between before-tax and after-tax wages. The tax wedge measures how much the government receives as a result of taxing the labor force. 2. A measure of the market inefficiency that is created when a tax is imposed on a product or service.