Cell Membrane
The cell membrane is what allows stuff to enter and leave the cell. It is made up of proteins, carbohydrates, and phospholipids. The proteins are the cells gateway. They are what opens up to bring in or kick out molecules from the cell. This action only takes place when the carbohydrates receive and send their signals. They determine what needs to be let out and brought into the cell and make the proteins function take course. The phospholipids are composed of two parts. The phospholipid head and the phospholipid tail. The phospholipid head is on the top and bottom of the cell. They attract water bringing the water either inside the cell, or pulling it out. The phospholipid tail does the opposite. They face the inner cell membrane and repel water. They keep water from sitting within the cell's membrane.