Cell Theory

Theory

is a proposition that explains a group of facts or phenomena in the natural world. It is supported and has been repeatedly confirmed by experiment and observation over a long period of time

Spontaneous Generation

Originally, scientists believed that cells were a result of spontaneous generation, the belief that living things come from non living things.
They thought this because they noticed after thunderstorms there seemed to be more frog and fish. They also noticed that when meat was left to spoil, maggots were produced.
The cell theory proved this concept to be wrong.

The Cell Theory

1. All organisms are made of cells.
2. All existing cells are produced by other living cells.
3. The cell is the most basic unit of life.

The Romans

When the Romans discovered they were able to make glass in the 1st century BC, things changed for the better. The discovery of the cell was made possible through the inventions of the microscope between 1665 and 1838.

Zacharias Janssen

Zacharias Janssen was a Dutch eye glass maker. He contributed to the cell theory by inventing the first compound microscope around 1600. This allowed scientists to investigate the world in new ways and lead to the discovery of the cell in the future.

Robert Hooke

• Used the compound microscope to observe cork.
• Hooke observed that cork is composed of small, hollow compartments.
• The parts prompted Hooke to think of small rooms (cells) in a monastery, so he gave them the same name: cells
• Investigated cork through experimenting with the compound microscope and came up with the name cells. He also wrote a book called Micrographia.
  Key Note: Hooke discovered the cell in 1665, which started formulating the cell theory.

Anton van Leeuwenhoek

• He was originally a draper, to trade, a person who sells cloth.
• Leeuwenhoek made his own 270x magnification compound microscope which he used to observe cloth.
• Leeuwenhoek microscope was more powerful than Hooke's compound microscope.
• From investigating and experimenting with his microscope, Leeuwenhoek became on of the first scientists to refer to living cells when he observed an abundant number single celled organisms which he called animalcules ( plant and animals) swimming in a drop of pond water.

Matthias Schleiden

• Fascinated with plant cells, Schleiden used the compound microscope and studied plant cells.
• From investigating and experimenting with plants, he claimed that all plant parts are made of cells.
• Discussed what he observed with his dear friend, German scientist, Theodor Schwann.

Theodor Schwann

-Studied plant and animal cells and was intrigued with the similarities between the two.

• Was able to determine that all animals were made of cells.
• Made the first statement of the cell theory that all living things were made of cell and cell products.

Robert Remak

• He discovered that the origin of cells was by the division of existing cells

• Concluded this after observing red blood cells from chicken embryos in various stages of division

Rudolph Virchow

• Virchow’s friends, Schleiden and Schwann were at odds with one another about if cells spontaneously or came from other cells. He decided to help them.

• Virchow reviewed the work of Remak, and noticed it showed how cells reproduced from other living cells.

• Virchow basically stole Remak’s work and claimed it as his own.

• Several years later, he had to admit that the work was not his, but Remak’s.

When was the cell theory complete?

1938 or 1939