Question

what are the functions of cell membranes

Answer 1

it hold the whole organs or group of cells and tissues inside it

Answer 2

The cell membrane gives the cell its structure and regulates the materials that enter and leave the cell. Like a drawbridge intended to protect a castle and keep out enemies, the cell membrane only allows certain molecules to enter or exit. Oxygen, which cells need in order to carry out metabolic functions such as cellular respiration, and carbon dioxide, a byproduct of these functions, can easily enter and exit through the membrane. Water can also freely cross the membrane, although it does so at a slower rate. However, highly charged molecules, like ions, cannot directly pass through, nor can large macromolecules like carbohydrates or amino acids. Instead, these molecules must pass through proteins that are embedded in the membrane. In this way, the cell can control the rate of diffusion of these substances.