Definition
Cell (Biology)
A cell is the smallest unit of life: a membrane-bounded volume that maintains itself, stores hereditary information, and reproduces. Every organism is either a single cell or is built from cells, so cells are the structural and functional atoms of biology.
A cell can be spelled out as a membrane-separated region in which a self-maintaining chemical reaction network persists. Let be the set of contained chemical species and the set of enzyme-catalysed reactions among them. The reaction network is
So a cell is a triple whose reproduces the conditions that make possible. Two architectural variants divide all cells: the prokaryotic, with no internal membrane-bound compartments, and the eukaryotic, whose nucleus and organelles compartmentalise the chemistry.