The cell membrane is a flexible membrane that surrounds all eukaryotic cells. The membrane holds all of the organelles inside of the cell and keeps certain solutes from coming into or leaving the cell.
The cell membrane is a selectively permeable membrane that is composed of hydrophilic heads and hydrophobic tails. This allows the membrane to form a lipid bilayer. The cell membrane is also embedded with cell membrane proteins. These proteins float in the bilayer and allow other solutes to enter and exit the cell. These proteins also act as messengers to the cell by binding to objects outside of the cell and transferring a message to the cell's nucleus.