The Development of the Cell Theory. The Cell Theory States: As written by Rudolph Virchow...

The Development of the

Cell Theory

The Cell Theory States:

• As written by Rudolph Virchow (1821-1902):– All living organisms are made of one or more cells.

– Cells are the basic units of structure and function in all organisms.

– All cells come from previously existing cells.

– The activity of an entire organism depends on the total activity of its independent cells.

Ancient Times

• Ancient peoples were always on the look-out for ways that organisms can be used by them.

• They passed on their understanding orally.

• Some civilizations supported “great thinkers” – and philosophers, but they rarely based their thoughts on observation or experiments.

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Timeline of the discoveries, thoughts and technologies that led to the development of the Cell Theory

334 B.C.E - Aristotle

• Greek philosopher, Aristotle, began to observe nature.

• He classified all known organisms as either a Plant or and Animal.

• He wrote that living things can arise spontaneously from non-living matter.

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1268 – 1st Eyeglasses

• Roger Bacon, an English friar made reference to a pair of eye glasses.

• This meant that glass was being developed and used in a way that makes it easier to see small things.

• Physics

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1590 – 1st Microscope

• Zacharias Janssen, a Dutch eyeglass maker, made the first microscope by placing two lenses on top of one another to make extra-large images.

• Physics

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1600’s• People started to suggest that

life can only come from other forms of life rather than through spontaneous generation (as was suggested by Aristotle).

• William Harvey said that maggots do not come from the meat itself but from tiny eggs too small to be scene.

• Biology/Medicine

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William HarveyEnglish Physician

1578-1657

1665 – 1st Cells Seen

• Robert Hooke (1635-1703) published a book with illustrations of tree bark as seen through a simple compound (2 lens) microscope.

• Physics

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1578-1657

• Francesco Redi (1626-1697) conducted experiments to prove that maggots do not appear in meat if flies cannot land on it!

• Biology

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1578-1657

1668 – 1st Experiments about origins of maggots

• Anton van Leeuwenhoek (1632-1723) reported being able to see tiny beasties (0.002 mm) using a simple single-lens microscope.

• Biology

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1674 – 1st Microscopic Organisms Seen!

• Carolus Linnaeus (1707-1778) began to show people the great diversity of living things by exploring methods of classifying them into 5 main Kingdoms.

• Biology

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1753 – Birth of Classification

• Microscopes became sturdier and easier to use.

• Flaws in glass production still caused images to be blurry and have coloured halos.

• Physics

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1770 – Advancement of Microscopes

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• Jane Haldimand (1769-1858) wrote textbooks for young people to learn about science.

• Words such as “cell”, “cellular system” and “Cellular tissue” appear in the book.

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1809 – 1st Science Texts for Students

• Microscope quality improved with the production of better glass.

• Many English companies competed to produce the best microscope.

• Physics

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1820’s – Better Glass = Better Lens

• Francois Vincent Raspail (1794-1878) wrote a book called “Every cell is derived from a preexisting cell”.

• Biology

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1825 – Book “Cells from Cells”

• Biology was becoming an important science and the body of knowledge was growing, especially since the improvement of microscopes.

• Scientists began to study the cell extensively.

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1830 – Cells are studied

• Robert Brown (1773-1858) was the first to think of the nucleus as a regular part of a living cell.

• The nucleus was still hard to see though without the invention of the electric light for his microscope.

• Biology

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1831 – Nucleus of Cell Found

• Matthias Jacob Schleiden (1804-1881) made the claim “All plants are made of cells”.

• Cells are alive!

• Biology

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1838 – Plant cells!

• Theodor Schwann (1810-1882) made the claim “All animals are made of cells”.

• Cells are the basic structure of life!

• Biology

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1839 – Animal cells!

• Alexander Carl Heinrich Braun (1805-1877) said:

“The cell is the basic unit of life”.

• Cells are made of protoplasm enveloped by a flexible membrane.

• Biology

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1845 – Cell Basic Unit of Life

• 18 year old, William Henry Perkin (1838-1907) developed a new purple dye for staining cell parts making it easier to see cell parts with a microscope.

• Chemistry

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1856 – Staining technique developed

• Charles Darwin (1809-1882) & Alfred Wallace (1823-1913) read their article on “Tendency of species to form variations”.

• Biology

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1858 – Article on Evolution

• Rudolph Virchow (1821-1902) developed his Cell Theory that is still largely accepted today.

• Biology

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1858 – Cell Theory Outlined

• Louis Pasteur (1822-1895) conducted a series of experiments that once and for all put to rest the idea of spontaneous generation and concluding that living organisms do not arise from non-living matter.

• Biology

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1860’s – The end of the “Spontaneous Generation” debate

The Development of the Cell Theory. The Cell Theory States: As written by Rudolph Virchow...

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