The Cell Theory
Some Random Cell Facts
The average human being is composed
of around 100 Trillion individual cells!!!
 It would take as many as 50 cells to
cover the area of a dot on the letter “i”

WOW!!!
1665 - Robert Hooke

1665- English Scientist, Robert Hooke,
examined cork cells. He is responsible for
naming the spaces in cork “cells” – which is
Latin for little rooms.
1673 - Anton Van Leuwenhoek
1673 - Dutch scientist, Anton Van
Leuwenhoek, used a handmade microscope to
observe pond scum & discovered single-celled
organisms.
 He called them “animalcules”

1838 – Matthias Schleiden

1838- German Botanist, Matthias Schleiden,
looked at plants cells. He concluded that
cells are present in all living things.
1839 – Theodore Schwann

1839- German scientist, Theodore
Schwann, stated that all animal tissues
are composed of cells. He & Schleiden
are credited with the first two parts of
the cell theory. (The cell is the basic
unit of life for all living things. All
organisms are composed of one or
more cells.)
1858 – Rudolf Virchow

1858- Rudolf Virchow, German physician, observed
that cells could not develop from anything but
existing cells. So he wrote the third part of the cell
theory. (All cells come from existing cells.)
Important Thoughts
 Cells
carry on similar functions such
as extracting energy from food to
sustain life.
 Organisms grow by “adding on
more cells,” NOT increasing the
size of their cells.
Why the Cell Theory is important?

The basic discovered truths about cells, listed
in the Cell Theory, are the basis for things
such as:

Disease/Health/Medical Research and Cures(AIDS,
Cancer, Vaccines, Cloning, Stem Cell Research, etc.)
What things are composed of cells? Give
example.
 What things are not composed of cells? Give
example.
 What are the three parts of the cell theory?
 A 15 year old and a 5 year old are made of
cells, how are their cells different?
