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.
Designed to position the pelvis in the natural position that all babies discover when learning how to sit up, itÊ¼s hard to believe that something so small can accomplish so much! The Wedge is a handy tool for learning HOW to sit solidly upright with ease. Simple to use, itâs small enough to fit in your bag and can be taken anywhereâto a movie, concert or sporting event.  Refer to the included instructions. Small & portable. Heavy duty construction; made of sturdy, non-skid fabric.