1. THE SCIENTISTS BEHIND CELL THEORY
UNIT 1
The cell
THE SCIENTISTS BEHIND CELL THEORY
Biology and Geology 4. Secondary Education

2. Click on the scientists to find out more.
UNIT 1
The scientists behind cell theory
A. van Leeuwenhoek
1673
R. Hooke
1665
Robert Brown
1831
J.E. Purkinje
1837
BEFORE CELL THEORY
R. Virchow
1855
Schleiden and Schwann
1839
G. Mendel
1860
PROPOSING CELL THEORY
Ramón y Cajal
1888
AFTER CELL THEORY
Sutton, Boveri and Morgan
1910
Watson and Crick
1975
L. Margulis
1981
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Biology and Geology 4. Secondary Education

3. The scientists behind cell theory
UNIT 1
The scientists behind cell theory
ROBERT HOOKE ( )
Hooke was born in Freshwater, England.
A prominent scientist, he was one of the founders of the Royal Society of London.
He is best known for his work in physics. He developed Hooke’s law of elasticity.
In 1665, while analysing a sheet of cork with a simple microscope, Hooke observed that it was made up of small, honeycomb- like compartments. He called them cells, from the Latin word for “small room.”
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Biology and Geology 4. Secondary Education

4. The scientists behind cell theory
UNIT 1
The scientists behind cell theory
ANTONIE VAN LEEUWENHOEK (1632 – 1723)
Leeuwenhoek was born in Delft, Netherlands.
He was a cloth merchant and haberdasher.
Leeuwenhoek’s interest in optics stemmed from his desire to improve the magnifying glasses he used to count the threads in cloth.
He made his own magnifying glasses and eventually crafted one of the first microscopes.
He made a simple microscope with which he became the first scientist to observe certain cells, such as bacteria, protozoa and red blood cells.
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Biology and Geology 4. Secondary Education

5. The scientists behind cell theory
UNIT 1
The scientists behind cell theory
ROBERT BROWN ( )
He was born in Montrose, Scotland.
A leading botanist, Brown carried out a significant study of the flora of Australia on an expedition of naturalists and discovered 1,200 new species.
He discovered the nucleus of eukaryotic cells.
While studying the leaves of different types of plants, he became the first scientist to observe and describe the cell nucleus and to affirm that it was present in all cells.
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Biology and Geology 4. Secondary Education

6. The scientists behind cell theory
UNIT 1
The scientists behind cell theory
JOHANNES EVANGELISTA PURKINJE ( )
He was born in Libochovice, Bohemia (now in the Czech Republic).
After studying medicine, he worked in the fields of anatomy, physiology and botany.
He was the first scientist to use a microtome to slice thin tissue sections in order to observe them with a microscope.
In 1837, he discovered Purkinje cells, large nerve cells with many branching dendrites found in the cerebellum.
In 1839, he discovered Purkinje fibres, tissues found in the heart that conduct electrical impulses to the ventricles.
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Biology and Geology 4. Secondary Education

7. The scientists behind cell theory
UNIT 1
The scientists behind cell theory
MATTHIAS JAKOB SCHLEIDEN ( )
He was born in Hamburg, Germany.
He studied law but gave it up to pursue botany.
His research focused on studying plants with microscopes.
He determined that all plants are composed of cells and that they grow as a result of the generation of new cells from the nucleus.
His findings, along with those of Theodor Schwann, form the first principle of cell theory.
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Biology and Geology 4. Secondary Education

8. The scientists behind cell theory
UNIT 1
The scientists behind cell theory
THEODOR SCHWANN ( )
He was born in Neuss, Germany.
He studied medicine and was particularly influential in the fields of physiology, anatomy and histology.
He researched digestive processes, fermentation and muscular contraction and classified the tissues in the body.
He also discovered Schwann cells, which generate the myelin sheath that covers the axons of neurons.
Building on Schleiden’s theory, he argued that animal tissues were also composed of cells.
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Biology and Geology 4. Secondary Education

9. The scientists behind cell theory
UNIT 1
The scientists behind cell theory
RUDOLF VIRCHOW ( )
He was born in Schivelbein, Germany.
He studied medicine, specialising in pathology (the study of diseases).
He was nominated for the Nobel Prize in Physiology or Medicine in 1901 and 1902.
He discovered thrombosis, improved autopsy techniques and studied a number of diseases.
He observed that diseases arose not in organs, but in their cells.
This led him to identify the principle of cell theory that holds that all cells come from pre- existing cells (Omnis cellula e cellula).
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Biology and Geology 4. Secondary Education

10. The scientists behind cell theory
UNIT 1
The scientists behind cell theory
GREGOR MENDEL ( )
He was born in Heinzendorf, Austria.
Mendel was an Augustinian friar at the Augustinian abbey in Brno and was ordained a priest in 1847.
Working in the monastery garden, he carried out experiments on plant hybridisation by crossing different types of pea plants.
From his experiments with peas, he deduced Mendel’s Laws of Inheritance, the foundation of modern genetics.
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Biology and Geology 4. Secondary Education

11. The scientists behind cell theory
UNIT 1
The scientists behind cell theory
SANTIAGO RAMÓN Y CAJAL
He was born in Navarre, Spain.
He studied medicine in Zaragoza and served as a medical officer in Cuba’s Ten Years’ War from 1873 to 1876.
Ramón y Cajal held professorships in histology and anatomy at a number of Spanish universities.
In 1888, he discovered that neurons were individual cells and analysed the processes that connect them, studying grey matter, a main component of the nervous system.
He was awarded the Nobel Prize in Physiology or Medicine in 1906.
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Biology and Geology 4. Secondary Education

12. The scientists behind cell theory
UNIT 1
The scientists behind cell theory
W. SUTTON,T. BOVERI and T.H. MORGAN
Walter Sutton (New York, ) and Theodor Boveri (Germany, ) developed the “Chromosome Theory of Inheritance.”
They demonstrated that alleles are inherited through chromosomes. They also studied cellular reproduction, mitosis and meiosis.
Their theory did not gain full acceptance until 1915, when it was corroborated by Thomas Hunt Morgan’s work with the fruit fly, Drosophila melanogaster.
Walter Sutton
Theodor Boveri
In 1933, Morgan was awarded the Nobel Prize in Physiology or Medicine for demonstrating that chromosomes contain the genes responsible for the inheritance of characteristics.
Thomas Hunt Morgan
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Biology and Geology 4. Secondary Education

13. The scientists behind cell theory
UNIT 1
The scientists behind cell theory
JAMES WATSON (1928) and FRANCIS CRICK (1916 – 2004)
James Watson (Chicago, USA, 1928) studied biology in Indiana and earned his doctorate in zoology.
Francis Crick (Northampton, England, – 2004) studied physics in London. After World War II, he focused on biology research.
In 1951, the two scientists began working together, combining their knowledge.
Building on Rosalin Franklin’s work with X-rays and DNA, Watson and Crick determined the double helical structure of DNA.
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Biology and Geology 4. Secondary Education

14. The scientists behind cell theory
UNIT 1
The scientists behind cell theory
LYNN MARGULIS ( )
She was born in Chicago, USA.
She entered university when she was 16, graduating with a degree in biology at age 20.
She is best known for her work in cell biology and genetics.
Her research involved the significance of bacteria in evolution.
Her theory that eukaryotic cells originated from symbioses between prokaryotic cells gained acceptance in 1981.
The “Serial endosymbiotic theory” was central to our understanding of the evolution of life.
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Biology and Geology 4. Secondary Education