Cell Theory

Cell Theory


  • Cell theory is a significant principle in biology that states all living organisms are composed of cells.
  • It highlights that the cell is the basic structural, functional, and biological unit of all known organisms.
  • It also stipulates that new cells arise only from pre-existing cells by a process known as cell division.

Key Points

  • The first part of cell theory, that all living things are composed of cells, was proposed in the early 19th century by scientists Matthais Schleiden and Theodor Schwann.
  • The second part of cell theory postulates that cells are the basic unit of structure and function in all organisms. This means every organism’s physical and biological functions are facilitated by cells.

  • The third part of cell theory, credited to Rudolf Virchow, proposes that all cells come from pre-existing cells. This opposes the defunct idea of spontaneous generation of life.

  • This theory also emphasises the continuity of life, as the characteristics and functions of cells are dictated by the DNA inside them and this DNA is passed on to daughter cells during division.


  • Cell theory underpins modern biological sciences and is also fundamental to the understanding of diseases and their treatments. If cells are not functioning correctly, this can lead to diseases.
  • Knowledge of cell theory assists in comprehending additional complex principles such as genetic inheritance, metabolism, and cell specialisation.
  • Understanding cell theory is essential to explore areas like biotechnology, where cell modification is employed to create beneficial products or outcomes.