Cell

In biology, the structural and functional unit of all living organisms, which exists as an independent unit of life in bacteria and protozoans, and first described by Robert Hooke (1635-1703) in 1665 with the aid of a light microscope.  In other living organisms, they form colonies or tissues.  Each cell contains protoplasm differentiated into cytoplasm and a nucleus containing DNA.  There are two main types of cells: prokaryotic cells as in bacteria and eukaryotic cells in which the nucleus is surrounded by a nuclear membrane and the cytoplasm is divided by membranes into connected cavities and separate compartments referred to as organelles (e.g., mitochondria and Golgi organs), as indicated in the figure below.

Typical human cell

See Cell theory, Cell recognition molecules, Chromosome, Cilia, Cytoplasm, DNA (deoxyribonucleic acid), Electrolyte, Eukaryote cell (or organism), Golgi apparatus (body or complex or organ), Histology, Ligands, Mitochondria, Nucleic acid, Nucleus (of a cell), Oligosaccharides, Organelles, Organogenesis, Progenitor cells, Prokaryote cell (or organism), Protoplasm, Stem cells