<Ol> <Li> Prokaryotes: Prokaryotes are relatively small cells surrounded by the plasma membrane, with a characteristic cell wall that may differ in composition depending on the particular organism . Prokaryotes lack a nucleus (although they do have circular or linear DNA) and other membrane - bound organelles (though they do contain ribosomes). The protoplasm of a prokaryote contains the chromosomal region that appears as fibrous deposits under the microscope, and the cytoplasm . Bacteria and Archaea are the two domains of prokaryotes . </Li> <Li> Eukaryotes: Eukaryotic cells are also surrounded by the plasma membrane, but on the other hand, they have distinct nuclei bound by a nuclear membrane or envelope . Eukaryotic cells also contain membrane - bound organelles, such as (mitochondria, chloroplasts, lysosomes, rough and smooth endoplasmic reticulum, vacuoles). In addition, they possess organized chromosomes which store genetic material . </Li> </Ol> <Li> Prokaryotes: Prokaryotes are relatively small cells surrounded by the plasma membrane, with a characteristic cell wall that may differ in composition depending on the particular organism . Prokaryotes lack a nucleus (although they do have circular or linear DNA) and other membrane - bound organelles (though they do contain ribosomes). The protoplasm of a prokaryote contains the chromosomal region that appears as fibrous deposits under the microscope, and the cytoplasm . Bacteria and Archaea are the two domains of prokaryotes . </Li> <Li> Eukaryotes: Eukaryotic cells are also surrounded by the plasma membrane, but on the other hand, they have distinct nuclei bound by a nuclear membrane or envelope . Eukaryotic cells also contain membrane - bound organelles, such as (mitochondria, chloroplasts, lysosomes, rough and smooth endoplasmic reticulum, vacuoles). In addition, they possess organized chromosomes which store genetic material . </Li> <P> Animals have evolved a greater diversity of cell types in a multicellular body (100--150 different cell types), compared with 10--20 in plants, fungi, and protoctista . </P>

Who are the different scientists that gave much contribution in the study of cells