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from Latin: cellula - "small chamber"
German: Zelle

1 Definition

Cells are fundamental biological organizational units which almost all known organisms are composed of. Cells are the smallest units of life that autonomously are capable of reproduction and self-preservation.

2 Background

All known cells – with the exception of a few specialized cell types – have certain components in common:

  • DNAgenetic information which serves as a construction plan for the other components of the cell
  • Proteins – either structural proteins or enzymes that are responsible for construction and biochemical functions of the cell, respectively.
  • Biomembranes which seal off the cells from their surroundings, act as filters, maintain contact with the surrounding area and subdivide larger cells into smaller compartments.

Cells also have basic functions in common:

  • Reproduction by way of cell division (mitosis)
  • Metabolism – intake of raw materials which are converted into new components and energy, and the disposal of waste products.
  • Protein biosynthesis – transcription from DNA to RNA and translation from RNA to proteins.

The human body is comprised of roughly 220 different cell types which combine to specific tissues.

Cells can be subdivided into prokaryotes, eukaryotes and archaea.

3 Organization of a typical eukaryotic cell

The most important structures of a eukaryotic cell are:

4 History of the discovery of cells

  • 1665: Robert Hooke first discovers cells in cork, then in living plants using one of the first microscopes
  • 1839: Theodor Schwann shows that animals and plants are made of cells
  • Louis Pasteur disproves the theory that cells can form spontaneously out of nothing (generatio spontanea).
  • Rudolf Virchow shows that every cell emerges from another cell (omni cellula ex cellula).


Specialties: Biology

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