Here's a breakdown:
* Cell membrane: This thin, flexible layer acts as a barrier between the cell's interior and its external environment. It's made up of a phospholipid bilayer, which means two layers of phospholipid molecules arranged tail-to-tail. This bilayer creates a selectively permeable barrier, allowing some substances to pass through while blocking others.
* Other structures:
* In addition to the cell membrane, plant cells have a rigid cell wall outside the membrane. This wall provides structural support and protection.
* Some cells may also have a glycocalyx, a layer of carbohydrates on the outer surface of the cell membrane. This layer helps with cell recognition and adhesion.
So, while the cell membrane is the primary structure surrounding all cells, other structures like the cell wall and glycocalyx can also be present depending on the type of cell.
