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

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1The cell

Biology and Geology 4. Secondary Education

THE SCIENTISTSBEHIND CELL THEORY

AFTER CELL THEORY

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1The scientists behind cell theory

R. Hooke

1665

R. Hooke

1665

A. van Leeuwenhoek

1673

A. van Leeuwenhoek

1673

Schleiden and Schwann1839

Schleiden and Schwann1839

R. Virchow1855

R. Virchow1855

Sutton, Boveri and Morgan1910

Sutton, Boveri and Morgan1910

Watson and Crick1975

Watson and Crick1975

L. Margulis1981

L. Margulis1981

BEFORE CELL THEORY

PROPOSING CELL THEORY

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Robert Brown1831

Robert Brown1831

J.E. Purkinje1837

J.E. Purkinje1837

Ramón y Cajal1888

Ramón y Cajal1888

G. Mendel1860

G. Mendel1860


ROBERT HOOKE (1635-1703)

• Hooke was born in Freshwater, England.

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• 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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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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ROBERT BROWN (1773-1858)

• 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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JOHANNES EVANGELISTA PURKINJE (1787-1869)

• He was born in Libochovice, Bohemia (now in the Czech Republic).

• In 1839, he discovered Purkinje fibres, tissues found in the heart that conduct electrical impulses to the ventricles.

• In 1837, he discovered Purkinje cells, large nerve cells with many branching dendrites found in the cerebellum.

• He was the first scientist to use a microtome to slice thin tissue sections in order to observe them with a microscope.

• After studying medicine, he worked in the fields of anatomy, physiology and botany.


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MATTHIAS JAKOB SCHLEIDEN (1804-1881)

• He was born in Hamburg, Germany.

• His findings, along with those of Theodor Schwann, form the first principle of cell theory.

• 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 research focused on studying plants with microscopes.

• He studied law but gave it up to pursue botany.


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THEODOR SCHWANN (1810-1882)

• 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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RUDOLF VIRCHOW (1821-1902)

• He was born in Schivelbein, Germany.

• This led him to identify the principle of cell theory that holds that all cells come from pre-existing cells (Omnis cellula e cellula).

• He observed that diseases arose not in organs, but in their cells.

• He discovered thrombosis, improved autopsy techniques and studied a number of diseases.

• He was nominated for the Nobel Prize in Physiology or Medicine in 1901 and 1902.

• He studied medicine, specialising in pathology (the study of diseases).


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GREGOR MENDEL (1822-1884)

• He was born in Heinzendorf, Austria.

• From his experiments with peas, he deduced Mendel’s Laws of Inheritance, the foundation of modern genetics.

• Working in the monastery garden, he carried out experiments on plant hybridisation by crossing different types of pea plants.

• Mendel was an Augustinian friar at the Augustinian abbey in Brno and was ordained a priest in 1847.


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SANTIAGO RAMÓN Y CAJAL

• He was born in Navarre, Spain.

• He was awarded the Nobel Prize in Physiology or Medicine in 1906.

• 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.

• Ramón y Cajal held professorships in histology and anatomy at a number of Spanish universities.

• He studied medicine in Zaragoza and served as a medical officer in Cuba’s Ten Years’ War from 1873 to 1876.


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W. SUTTON,T. BOVERI and T.H. MORGAN

• 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.

• 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.

• They demonstrated that alleles are inherited through chromosomes. They also studied cellular reproduction, mitosis and meiosis.

• Walter Sutton (New York, 1877-1916) and Theodor Boveri (Germany, 1862-1915) developed the “Chromosome Theory of Inheritance.”

Walter Sutton

Theodor Boveri

Thomas Hunt Morgan


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JAMES WATSON (1928) and FRANCIS CRICK (1916 – 2004)

• James Watson (Chicago, USA, 1928) studied biology in Indiana and earned his doctorate in zoology.

• Building on Rosalin Franklin’s work with X-rays and DNA, Watson and Crick determined the double helical structure of DNA.

• In 1951, the two scientists began working together, combining their knowledge.

• Francis Crick (Northampton, England, 1916 – 2004) studied physics in London. After World War II, he focused on biology research.


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LYNN MARGULIS (1938-2011)

• She was born in Chicago, USA.

• The “Serial endosymbiotic theory” was central to our understanding of the evolution of life.

• Her theory that eukaryotic cells originated from symbioses between prokaryotic cells gained acceptance in 1981.

• Her research involved the significance of bacteria in evolution.

• She is best known for her work in cell biology and genetics.

• She entered university when she was 16, graduating with a degree in biology at age 20.


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

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