Cell Theory & History

Cell Theory

The foundational biological principle stating that cells are the basic structural and functional units of living organisms, all organisms consist of one or more cells, and cells arise from pre-existing cells.

Three Postulates of Classic Cell Theory

1. Cells are the building blocks and functional units of living organisms. 2. All living organisms contain one or more cells. 3. Cells arise from pre-existing cells.

Additions of Modern Cell Theory

1. Genetic material ($DNA$) is passed between cells during cell division. 2. Cells of organisms within similar species are mostly identical structurally and chemically. 3. Energy flows within cells.

Cytology

The study of cell structure, function, and chemistry.

Robert Hooke

Scientist who observed cork under a microscope in 1665 and coined the term "cell" because the box-like structures reminded him of small rooms (cellula).

Anton van Leeuwenhoek

Microscopist who was the first to observe living cells (bacteria, protozoa, sperm, and red blood cells) using handcrafted single-lens microscopes, calling them "animalcules".

Robert Brown

Botanist who identified and named the cell nucleus in plant and orchid tissues in 1831.

Félix Dujardin

Biologist who discovered the jelly-like living substance inside cells, naming it "sarcode" (later known as protoplasm and cytoplasm).

Matthias Schleiden

German botanist who stated in 1838 that all plants are composed of cells.

Theodor Schwann

German zoologist who stated in 1839 that all animals are composed of cells.

Rudolf Virchow

German physician who stated in 1855 that all cells arise from pre-existing cells (Omnis cellula e cellula), helping to disprove the idea of spontaneous generation.

Omnis cellula e cellula

Latin phrase meaning "all cells arise from pre-existing cells."