The 3 postulates of the Cell Theory are:
-Every living being is composed of cells, therefore they are the minimal functional unit of life, in their different levels of structural complexity. One single
cell is enough to make up an organism, but also multiple cells can organize in colonies or in a single organism, diversifying their functions and having a margin of independence quite elevated as a whole.
-All of the vital functions of living organisms have a place inside the cell, through biochemical processes and are controlled by substances that the cell secrete. Each cell operates as a unique open system, that exchanges matter, and energy with its environment in a controlled way. Moreover, in each cell of an organism are present the same vital functions that are in the organism itself, that is birth, growth, reproduction, and death.
-Every existing cell comes from a previous cell, by cell division, or by formation from stem cells.