Cell (biology)

The cell is the structural and functional unit of all living organisms, sometimes called the "building blocks of life." Some organisms, such as bacteria, are unicellular, consisting of a single cell. Other organisms, such as humans, are multicellular, (humans have an estimated 100,000 billion = 1014 cells).

History

• 1632-1723: Antony van Leeuwenhoek teaches himself to grind lenses, builds a microscope and draws protozoa, such as Vorticella from rain water, and bacteria from his own mouth.
• 1665 : Robert Hooke discovers cells in cork, then in living plant tissue using an early microscope.

::...I could exceedingly plainly perceive it to be all perforated and porous, much like honeycomb...these pores or cells, were not very deep, but consisted of a great many little boxes... – Hooke describing his observations on a thin slice of cork.

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• 1839 : Theodor Schwann and Matthias Jakob Schleiden elucidate the principal that plants and animals are made of cells, concluding that cells are a common unit of structure and development, thus founding the Cell Theory.
• The belief that life forms are able to occur spontaneously (generatio spontanea) is contradicted by Louis Pasteur (1822-1895).
• Rudolph Virchow states that cells always emerge from cell divisions (omnis cellula ex cellula).
• 1931: Ernst Ruska builds first transmission electron microscope (TEM) at the University of Berlin. By 1935 he has built an EM with twice the resolution of a light microscope, revealing previously unresolvable organelles.
• 1953: Watson and Crick made their first announcement on the double-helix structure for DNA on February 28.
• 1981: Lynn Margulis published Symbiosis in Cell Evolution detailing the endosymbiotic theory.