Cell Theory and History

Cell theory

A foundational biology concept stating that all living things are composed of cells, the cell is the basic unit of life, and all cells arise from pre-existing cells.

Postulates of the cell theory

The classical statements: (1) All living things are made of cells; (2) The cell is the basic unit of life; (3) All cells come from pre-existing cells.

Cell as the basic unit of life

The smallest unit capable of performing all the essential life processes.

Robert Hooke

English scientist who coined 'cell' after observing cork under a microscope; described in Micrographia (1665).

Micrographia

Hooke's 1665 book detailing microscopic observations, including the cork 'cells'.

Cork cell

The cell-like units Hooke observed in cork, which led to the term 'cell'.

Antoni van Leeuwenhoek

Dutch tradesman who built powerful simple microscopes and observed living microorganisms (animalcules).

Animalcules

Leeuwenhoek’s term for microscopic living organisms, including bacteria and protozoa.

Barthélemy Dumortier

French-Belgian botanist who first described cell division in plants.

Robert Brown

Botanist who described the nucleus as an opaque spot in plant cells.

Nucleus

Central organelle named by Brown; a defining feature observed in many cells.

Nucleolus

Structure within the nucleus first described by Valentin as a distinct region involved in ribosomal RNA synthesis.

Matthias Schleiden

German botanist who proposed that plants are composed of cells.

Theodor Schwann

German physiologist who proposed that animals are composed of cells; co-founder of the cell theory.

Rudolph Virchow

Physician who stated 'omnis cellula e cellula'—all cells arise from pre-existing cells.

Spontaneous generation

Belief that life can arise from nonliving matter; disproved by later experiments.

Francesco Redi

Italian scientist who challenged spontaneous generation with meat-in-jars experiments showing maggots come from eggs of flies.

Lazzaro Spallanzani

Italian scientist who boiled broth and sealed jars to show life did not arise from air; improved Redi's experiment.

Louis Pasteur

French chemist who disproved spontaneous generation using swan-neck flask experiments.

Swan-neck flask experiment

Pasteur's demonstration that dust and microbes come from the air; curved neck prevents contamination, disproving spontaneous generation.

Gregor Mendel

Father of modern genetics; studied pea plants to establish inheritance laws.

Watson and Crick

Scientists who discovered the double-helix structure of DNA in 1952.

Modern Cell Theory

Expansion of the original theory to include DNA as hereditary material, chemical similarity among cells, fundamental cellular processes, and the role of organelles in cell activity.