Question

How do cell membranes protect the cell?

Answer 1

The cell membrane, also known as the plasma membrane, is found in almost every cell and separates the interior of the cell from the outside environment having a lipid bilayer that is semipermeable. The cell membrane regulates the transport of materials coming in and out of the cell.

Complete answer:
The plasma membrane, or cell membrane, usually protects a cell by providing a fixed environment inside the cell, and that membrane consists of several different functions. First is to transport nutrients into the cell and also to transport toxic substances out of the cell. Another is that the membrane of the cell, which is the plasma membrane, has proteins on it which interact with other cells.
Those proteins are either glycoproteins, meaning there are sugar and a protein moiety, or they can be lipid proteins, meaning that there are fat and a protein. And those proteins which stick outside of the plasma membrane will allow for interaction of one cell with another cell. The cell membrane provides some structural support to the cell.
There are different types of plasma membranes in different types of cells, and the plasma membrane has in it is generally a lot of cholesterol as its lipid component. Differing from certain other membranes from within the cell.
Different microbes are present, such as bacteria and algae, having different protective mechanisms. They are having a cell wall outside of them, and that cell wall seems much tougher and is structurally more sound than a plasma membrane is.

Note: Cell membrane serving as barriers and the gatekeepers. Only Small polar molecules, like water and ethanol, can pass through membranes also, but they very slowly. On the other side, cell membranes usually restrict diffusion of highly charged molecules, such as ions and large molecules, sugars and amino acids.