A cell

A living being is made up of cells.  Everybody knows that.  But what actually is a cell?  A cell is the basic unit of living being.  However small the living thing is, it must contain at least one cell.  In a human being, there are millions and millions of cells, and there are hundreds of different type of cell.

Although there are different types of cells, the basic makeup of a cell is always the same (with red blood cell, which has no nucleus, as an exception).  The most important part of the cell is the nucleus.  The nucleus is merely a bunch of DNA enclosed by membrane called the nuclear envelop (NE).  Outside the nucleus is the cytoplasm, with all the little parts like mitochondria, which are not important for us here.  The cytoplasm is supported by a network of fibres called the cytoskeletons.  Then, everything is enclosed in a cell membrane (in plant's case, also with a cell wall).