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Studying Cells Tutorial

Major Events in Cell Biology

History of studying cells
Because of the limitations of the human eye, much of the early biological research concentrated on developing tools to help us see very small things. As imaging technology became more sophisticated, biological discoveries abounded. Below is a timeline detailing some of those major events in biology.
Major events in cell biology & Imaging ----1655 Robert Hooke observes cells of a cork tree through a primitive microscope.--1674 Leewenhoek discovers protozoa.--1683 Leewenhoek discovers bacteria.--1838 Schleiden & Schwann propose the Cell Theory.--1857 Kolliker describes mitochondria in muscle.--1882 Koch uses aniline dyes to identify bacteria causing TB and cholera.--1898 Golgi stains cells with silver nitrate, discovering the Golgi apparatus.--1931 Ruska builds the first transmission electron microscope.--1965 1st. commercial scanning electron microscope.--1997 Sheep "cloned."

The Cell Theory
When Schleiden and Schwann proposed the cell theory in 1838, cell biology research was forever changed. The cell theory states that:
  1. All life forms are made from one or more cells.
  2. Cells only arise from pre-existing cells.
  3. The cell is the smallest form of life.
The cell theory also provides us with an operational definition of "life." The tutorial on prokaryotes, eukaryotes, and viruses explores this concept in more detail.

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