The Discovery of Cells
7.1 The History of the Cell Theory
The invention of microscopes made it possible for scientists to view and study cells. Cells are the basic units of living organisms. In the 16oo's, Anton van Leeuwenhoek( LAY vun hook) used a single lens microscope to view bacteria, which until the could not be seen. Later, compound light microscope used several lenses and could magnify object up to 1500 times their original size.
The scientist Robert Hooke looked at thin slices of cork under a compound microscope. Thinking the small shapes he saw looked like small rooms, he called them cells.
By he 1800s, microscopes had been improved allowing scientists to make other important observation. First, Robert Brown, a Scottish scientist, discovered that cells had an important inner compartment, the nucleus (NEW klee us). Then, Rudolf Virchow figured out that the nucleus controls the cell's activities. Later, two German biologist, Matthias Schleiden and Theodore Schwann, did their own experiments and learned that all living things are made of one or more cells.
What is cell theory?
The environment of Schleiden, Schwann, and other scientists led to the development of what is called the cell theory. It is one of the fundamental ideas of the science of biology. The three main parts of the cell theory are summarized below:
All living things are made up of one or more cells.
Cells are the basic units of structure and function in living things.
All cells come over cells.
How do microscope help scientist learn about cells?
In the 1930s and 1940s, microscopes were improved. Electron microscope allowed scientists to magnify an object up to 500 000 times using a beam of electrons instend of a beam of light. A scanning electron microscope (SEM) lets scientists see a cell's three-dimensional shape. A transmission electron microscope (TEM) lets scientists see the stucture inside a cell.
Microscope are continually being improved so...