Study Guide: Cell Theory and Organization of Life
There were many different scientists that had an influence in the discovery of cells. Below, you will
find a list of scientists involved and their contributions to the scientific community.
1. Robert Hooke- (1665) built a microscope and looked at cork from a plant. He described the cork as
looking like hundreds of boxes, and named these boxes “cells” which means “little boxes”.
2. Anton van Leeuwenhoek- (1675) built a microscope to look at pond water. He saw many small
creatures swimming around and named them “animalcules” which means “little animals”. He was
likely the first person to see living cells. He also was the first person to see bacteria.
3. Matthias Schleiden- (1838) Botanist who made the observation and conclusion that all plant parts are
made of cells. He came to this conclusion after looking at thousands of plant slides and reading about
other scientists’ research.
4. Theodor Schwann- (1839) Zoologist who stated that all animal tissues are made of cells. He concluded
this after studying numerous animals under the microscope.
5. Rudolf Virchow- (1858), pathologist saw that cells could not develop from anything except other cells.
CELL THEORY:
A. ALL ORGANISMS ARE COMPOSED OF ONE OR MORE CELLS. (Schwann)
B. CELLS ARE LIVING THINGS’ MOST BASIC UNIT OF STRUCTURE AND FUNCTION. (Schwann)
C. ALL CELLS COME FROM CELLS. (Virchow)
ORGANIZATION OF LIFE:
Cells tissues  organs  organ systems  organisms
Away to think about this is a cell is the smallest living thing. A group of cells working together is called tissue, a group of
tissues working together is called an organ, organs working together make up an organ system, and all of your organ
systems working together make up an organism.