According to the cell theory, living organisms are composed of cells.
Organisms consisting of only one cell carry out all functions of life in that cell.
All living organisms consist of cells. Cell is a complex multicomponent system, performing a number of functions.
The living beings can be unicellular (amoeba or bacteria, for example) and multicellular (animals, plants, fungi). Multicellular organisms are larger and consist of many cells.
All living cells have the same number of features:
- every living cell is surrounded by a membrane, which separates the cell contents frome everything else outside;
- cells contain genetic material which stores all of the instructions needed for the cell's activities;
- most of these activities are chemical reactions and enzymws, which are produced inside the cell, take part in these proccesses;
- cell is a generator of energy for all living proccesses, reactions and activities.
That is why a cell is a functional and structural unit of all living things. There is no life out of the cell. Nothing smaller than the cell can survive.