Every cell in every organism is surrounded by a cell membrane, a border between the inside of the cell and the outside.
Every cell in every organism is surrounded by a cell membrane, a border between the inside of the cell and the outside.
Micro-level gatekeeper
The cell membrane plays an important role in all sorts of processes within and between cells. It decides what and how much water, ions and other substances enter and leave the cell and also has a signalling function.
Head and tail
Cell membrane is made up of a double layer of phospholipids. These are fatty molecules comprising a hydrophilic (attracted by water) head and hydrophobic (repelled by water) tail (fatty acids). Between the phospholipids, there are also proteins which can have various functions. Transport proteins, for instance, move molecules in and out of the cell.