Cell Theory & Types Study Guide
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- British scientist, who in 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- Dutch merchant, in 1673, built a microscope to look at pond scum. He saw
many small creatures swimming around and named them “animalcules” which means “little animals”.
He also was the first person to see bacteria.
3. Matthias Schleiden- German scientist, in 1838, 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- German scientist, in 1839, stated that all animal tissues are made of cells. He
concluded this after studying numerous animals under the microscope. He also wrote the first two
parts of the cell theory:
a. ALL ORGANISMS ARE COMPOSED OF ONE OR MORE CELLS.
b. THE CELL IS THE BASIC UNIT OF LIFE IN ALL LIVING THINGS.
5. Rudolf Virchow- German scientist, in 1858, saw that cells could not develop from anything except
other cells. He then wrote the third part of the cell theory:
a. ALL CELLS COME FROM EXISTING CELLS.
CELL THEORY
1. ALL ORGANISMS ARE COMPOSED OF ONE OR MORE CELLS. (Schwann)
2. THE CELL IS THE BASIC UNIT OF LIFE IN ALL LIVING THINGS. (Schwann)
3. ALL CELLS COME FROM CELLS. (Virchow)
Prokaryotic Cell
1. No complex organelles
2. Circular DNA
3. No nucleus
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Only unicellular
Most have a cell wall
Reproduce asexually by binary fission
Thought to have been the first cells
Much smaller than eukaryotic cells
Has DNA, ribosomes, cell membrane, and cytoplasm
Eukaryotic Cell
1. Has a lot of organelles
2. Linear DNA
3. Has a nucleus
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Can be unicellular or multicellular
Only plants and some fungi have cell walls
Reproduce mainly sexual, some asexually
Thought to have evolved from prokaryotes
Much larger than prokaryotic cells
Has DNA, ribosomes, cell membrane, cytoplasm (as well as other organelles)
Organisms that are made up of the two types of cells
Prokaryotic Cells:
Archaebacteria
Eubacteria
Eukaryotic Cells:
Animals
Plants
Fungi
Protists
Similarities and Differences
Between
Prokaryotic and Eukaryotic Cells
Similarities
Both types have DNA, cytoplasm, cell membranes, and
ribosomes. They also have all seven living characteristics in
common (grow and develop, DNA, respond to stimuli,
reproduce, excrete, use energy, and they are cells of course)
Differences
Prokaryotic
 No membrane-covered organelles
 No Nucleus
 Circular DNA
 Much smaller than eukaryotic cells
 Theory is that they are much older than eukaryotic cells
 Has three general shapes- spheres, spirals, or rod shaped
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Eukaryotic
Bunches of membrane-covered organelles
Has a nucleus
Linear DNA
Larger than prokaryotic
Theory is that they evolved from prokaryotic cells
Animal- usually round shaped
Plant- usually rectangular shaped