Cells structural organisation

STRUCTURAL ORGANISATION OF CELL 

If we study a cell under a microscope, we would come across three features in almost every cell: plasma membrane, nucleus and cytoplasm.

Let's see how these features organised

PLASMA MEMBRANE(CELL MEMBRANE)

This is the outermost covering of cell that separates the content of the cell from its external environment.  

The plasma membrane allows the entry and exit of some materials in and out of the cell,and also prevents movement of some other materials. The cell membrane, therefore, is called a selectively permeable membrane.

The plasma membrane is flexible and is made up of organic molecules called lipids and proteins.

However, we can observe the structure of the plasma membrane only through an electron microscope.

CELL WALL

The cell wall lies outside the plasma membrane.

Plant cell, in addition to the plasma membrane, have another rigid outer covering called the cell wall.

The plant cell wall is mainly composed of cellulose.

When a living plant cell loses water through osmosis there is shrinkage or contraction of the contents of the cell away from the cell wall. This phenomenon is known as plasmolysis. 

NUCLEUS

The nucleus is situated inside cell has a double layered covering called nucleus membrane. The nuclear membrane has pores which allow the transfer of material from inside the nucleus to its outside.

Nucleus contains chromosomes which contain information for inheritance of features from parents to next generation in the form of DNA(Deoxyribo Nucleic Acid) molecules.

The nucleus plays a central role in cellular reproduction, the process by which a single cell divides and forms two new cells.

CYTOPLASM

There is a large region enclosed by cell membrane, it is called the cytoplasm, is the fluid content inside the plasma membrane.

cytoplasm contains many organised organelles. Each of these organelles performs a specific function for the cell.