 All living things are made of one or more 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.

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.

 ROBERT HOOKE who examined thin slices of CORK and other plant tissues.  He found that they contained BOXLIKE structures which he called CELLS.

…DEAD cells. He never observed the cells of living things.

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

 1824 – Henry Dutrochet  Proposed that all living things were made from cells.  1831 – Robert Brown  Observed and named the NUCLEUS

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

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

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

They were also able to describe the events of cell DIVISION in which one cell splits to form TWO cells.

 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.

 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.