Cell theory

 a theory in biology that includes one or both of the statements that the cell is the fundamental structural and functional unit of living matter and that the organism is composed of autonomous cells with its properties being the sum of those of its cells.

eukaryotic

are organisms whose cells have a nucleus enclosed within membranes, unlike prokaryotes (Bacteria and Archaea), which have no membrane-bound organelles.

prokaryotic

are unicellular organisms that lack organelles or other internal membrane-bound structures. 

nucleus

the central and most important part of an object, movement, or group, forming the basis for its activity and growth.

organelle

any of a number of organized or specialized structures within a living cell.

cell wall

a rigid layer of polysaccharides lying outside the plasma membrane of the cells of plants, fungi, and bacteria. In the algae and higher plants it consists mainly of cellulose.

vacuole

a space or vesicle within the cytoplasm of a cell, enclosed by a membrane and typically containing fluid.

endoplasmic reticulum

a network of membranous tubules within the cytoplasm of a eukaryotic cell, continuous with the nuclear membrane. It usually has ribosomes attached and is involved in protein and lipid synthesis.