Source: Compound Microscope,

In the lesson titled “Plant and Animal Cells”, you learned the eight characteristics of living things. One of those characteristics is the following:

All living things are made of one or more cells.

In order to study cells, scientists must use microscopes. You have probably used microscopes in science class similar to the one pictured here.

Scientists use large electron microscopes, like the ones pictured below, in microscopy. Electron microscopes can magnify objects up to 10,000,000 times!

Source: Transmission Electron Microscope, The Chinese University of Honk Kong
Hitachi S-7800 SEM, Arizona State University

How were cells discovered?

The discovery of the cell started with the invention of the microscope.

Interactive exercise. Assistance may be required. Click on each blue dot in the timeline below to learn more about the discovery of the cell and the cell theory.

As technology continued to develop and scientists learned more about the structure and functions of cells, the cell theory was added to. The modern cell theory states the following:

  1. All organisms are made up of cells.
  2. The cell is the basic unit of structure and function in living organisms.
  3. All cells come from other cells by cell reproduction.
  4. Cells contain hereditary information, which is passed from cell to cell during cell division.
  5. All cells are the same in chemical composition.
  6. All energy flow (metabolism and biochemistry) of life occurs within the cell.

Sources for images used in the interactive in this section, as they appear, top to bottom: