Cell theory is a fundamental concept in biology that explains how cells contribute to life. According to this theory, cells arise from pre-existing cells through a process of cell division, rather than spontaneously generating. This principle was established in the 19th century by scientists such as Matthias Schleiden and Theodor Schwann, who proposed that all living organisms are composed of cells, and that the cell is the basic unit of life.
To elaborate, the concept emphasizes three main tenets: first, all living things are made up of cells; second, the cell is the simplest unit of life; and third, all cells arise from existing cells. This means that life is continuous and interconnected, as new cells form as a result of division of existing ones, ensuring the propagation of life and continuity of genetic information.