Cell Theory Video The Wacky History of Cell Theory The Cell Theory Cell Theory Video The Wacky History of Cell Theory

All living things are made of one or more CELLS.

while others have MANY cells. Some organisms consist of ONE cell while others have MANY cells.

Regardless of the number of cells, living things must carry on all the life PROCESSES. This cell is in the process of cell REPRODUCTION.

Since cells cannot be seen with the naked eye, the invention of the….. MICROSCOPE was very important to the discovery of cells. It was not until the mid-1600’s that microscopes were used to examine the parts of living things.

One of the first scientists to use a compound microscope was….. ROBERT HOOKE who examined thin slices of CORK and other plant tissues. He found that they contained BOXLIKE structures which he called CELLS.

What Hooke saw, however, were the walls of…. …DEAD cells. He never observed the cells of living things.

Anton van Leeuwenhoek examined drops of…. POND water using a very powerful single-lens microscope. Leeuwenhoek also observed human BLOOD cells and BACTERIA which are the smallest kinds of cells.

Proposed that all living things were made from cells. It was not until the early 1800’s that the cellular nature of living things began to gain attention. 1831 – Robert Brown Observed and named the NUCLEUS 1824 – Henry Dutrochet Proposed that all living things were made from cells.

Schleiden and Schwann 1838 – Matthias Schleiden Developed the theory that all plants contained cells. 1839 – Theodor Schwann Proposed that all animals contained cells.

Purkinje and Virchow 1855 – Rudolf Virchow 1839 – Johannes Purkinje Stated that all living cells came from other cells. 1839 – Johannes Purkinje Used the term “protoplasm” to refer to the jelly-like material in a cell.

Schultze and Dujardin 1861 – Max Schultze Defined “protoplasm” as the physical basis of life. 1861 – Felix Dujardin Recognized the existence of one-celled organisms.

By the end of the 1800’s scientists discovered many structures that lie WITHIN a cell. They were also able to describe the events of cell DIVISION in which one cell splits to form TWO cells.

As a result of the work of these scientists, the main points of the CELL THEORY were stated. The Cell Theory states that…. All organisms are made of ONE or more CELLS All cells carry on LIFE ACTIVITIES New cells ARISE only from other LIVING cells by the process of CELL DIVISION.

There are THREE (3) exceptions to the cell theory. The first cell could not have come from a pre-existing cell. Although viruses can carry on many life processes, they DO NOT contain cells Mitochondria and chloroplasts contain their own DNA and can reproduce within a cell.