The cell is the basic unit of all living organisms. Robert Hooke first discovered cells in 1665 while viewing cork under a microscope and noticed compartments resembling cells. Anton van Leeuwenhoek later invented an improved microscope and was able to study living cells. The collective work of scientists in the following years led to the formulation of the cell theory, which states that all organisms are composed of one or more cells, cells are the basic unit of structure and function of all living things, and new cells are produced from existing cells.

1. THE CELL

2. The cell is the basic unit of all living
organisms. It is the smallest structure
that is able to carry out the basic
functions of life

3. How were cells discovered?

4. Robert Hooke first
discovered cell while
viewing cork
specimen. He noticed
little rooms that
resembled cells, and
thus the term “cells”
was born. Hooke was
not able to observe
living cells but they
were remnants of a
cell specifically the
cell wall.

5. The invention of a
much better
microscope by Anton
van Leeuwenhoek led
to the study of living
cells.

6. The following years,
other scientists also
studied living cells;
their collective work
led to the formulation
of the cell theory.

7. What does the cell
theory state?

8. All organisms are
composed of one or
more cells. Cell is the
structural unit of all
living organisms
Matthias Schleiden
proposed that all
plants are composed
of cells. The following
year, Theodore
Schwann made a
similar statement
regarding animals

9. Cells come from pre-
existing cells Rudolph
Virchow showed that
cells self reproduce
which contributed to
the third tenet of the
cell theory.