Cell membrane

Although cells vary greatly, they contain cytoplasm enclosed by a cell membrane and have genetic material made of DNA. The position of this genetic material provides the key distinction between two broad types of cell: eukaryotic and prokaryotic.

Although different types of cell are organised differently, all the cells considered here have a cell membrane and ribosomes.

Every cell has a cell membrane surrounding its cytoplasm. The membrane is a selective barrier: it regulates which substances enter and leave, so the cell can take in what it needs and remove wastes. It also contains receptor molecules that bind particular signals outside the cell, allowing the cell to respond.

Both plant cells and prokaryotic cells, such as bacteria, have a cell membrane. It separates the inside of the cell from its surroundings. These cells also have a cell wall outside the membrane, but it is the partially permeable membrane that controls which substances can cross.