As we know, all organisms are made up of cells and their produces.
Study of structure and composition of cell is known as Cytology.
Cell Biology correlates the structure with the function (life processes) of cells.
All organisms are made up of cells, whether unicellular or multicellular.
Cell is the basic unit of life and structural/functional unit of an organism.
Robert Hooke (1665) : Observed the suberized cell walls with a honey comb like pattern in a thin slice of cork and named them ‘cellulae’ as published in his book: Micrographia
Marcello Malpighi (1671) and Grew studied the plant tissues and called the cavities of cellular wall as ‘vesicles’ or utricles’
Leeuwenhoeck (1683) : First to observe living cells like bacteria, protozoa, red blood cells and sperm etc.
Robert Brown (1831) : Found a small sphere within the cells of orchid roots which was later called as ‘nucleus’