Features Of Cell (Why cell?)

A cell can be thought of as a bag of chemicals that is capable of surviving and replicating itself.

Inside the bag, the chemicals differ in various ways from those outside the bag.

Without a barrier between the bag and the environment, the chemicals would mix freely by diffusion and the differences could not be maintained. Life could not exist.

Cell Membrane:

The barrier is a very thin membrane that acts rather like a border control between two countries, controlling the traffic of molecules into and out of the cell.

All living cells are surrounded by a membrane.

It is known as a cell surface membrane to distinguish it from any membranes that occur inside the cell.

There are two models proposed for the cell membrane known as the Lock and Key Model and the other is the Fluid Mosaic Model.