Cell theory

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The cell theory is a scientific theory that is one of the foundations of biology. The generally accepted parts of cell theory include:

  • The cell is the fundamental unit of structure and function in living things.
  • All organisms are made up of one or more cells.
  • All cells come from pre-existing cells through cellular division.
  • Cells carry genetic material passed to daughter cells during cellular division.
  • All cells are essentially the same in chemical composition.
  • Energy flow (metabolism and biochemistry) occurs within cells.

The three main parts of the cell theory are:

  1. All living organisms are composed of one or more cells.
  2. Cells are the most basic unit for function and structure of all organisms.
  3. All cells come from cells that already exist.

This theory also contains two exceptions:

  1. Viruses are considered by some to be alive, yet they are not made up of cells.
  2. The first cell did not originate from a preexisting cell.

The cell theory was originally developed by Theodor Schwann and Matthias Jakob Schleiden, and fully accepted by the work of Louis Pasteur, specifically his work regarding microbes. Cells are a basic unit of biology.

The cell was first discovered by Robert Hooke in 1663. He remarked that it looked strangely similar to cells in which monks inhabit. However what he actually discovered was a part of a cork (or dead plant) and what he was looking at was the empty cell walls with no nucleus in the center. The first man to witness a live cell under a microscope was Anton van Leeuwenhoek in 1673.

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