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.
Definition of QUARTZ WEDGE. : a piece of quartz cut in a thin wedge and used in the optical determination of minerals and in the study of polarized light. ADVERTISEMENT. This word doesn't usually appear in our free dictionary, but the definition from our premium Unabridged Dictionary is offered here on a limited basis.