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The development of cell theory
Transcript of The development of cell theory
of cell theory Robert Hook Zacharias Janssen Anton Leeuwenhoek
1674 Matthias Schleiden Theodor Schwann Cell Theory Discovered the cell in 1665 when he observed a very thin slice of cork (under a coarse, compound microscope) and saw a multitude of tiny pores that he remarked looked like the walled compartments a monk would live in. Because of this association, Hooke called them cells, the name they still bear. He did not know the real function and structure of the cell back then, he described what he saw in Micrographia in 1665. 1590
Hans and Zacharias Janssen were the inventors of the first optical telescope and the single lens optical compound microscope. Both Hans and Zacharias were dutch spectacle-makers in middle-burg, Netherlands. Around 1590, Hans and Zacharias Janssen created the first compound microscope. He was known as the "father of microbiology. Leeuwenhoek is known to have made over 500 "microscopes," of which fewer than ten have survived to the present day. Anton Leeuwenhoek discovered blood cells and microscopic animals such as nematodes and rotifers. In 1839, German zoologist Theodor Schwann published the work "Microscopic Investigation on the Structure and Growth of Animals and Plants", which became known as the Cell Theory. In his work Schwann states that all animal and plant tissues are formed by cells. He based his statement in the fact that the nucleus is present in all kinds of cells and also in the common basic development process initiated by the nucleus. The modern tenets of the Cell Theory include:
1. All known living things are made up of cells.
2. The cell is structural & functional unit of all living things.
3. All cells come from pre-existing cells by division.
4. Cells contains hereditary information which is passed from
cell to cell during cell division.
5. All cells are basically the same in chemical composition.
6. All energy flow of life occurs within cells. His main discoveries were:
the infusoria (protists in modern zoological classification), in 1674
the bacteria, (e.g. large Selenomonads from the human mouth), in 1676
the spermatozoa in 1677
the banded pattern of muscular fibres, in 1682. Schleiden, Matthias Jakob (1804-81), German botanist, who, with the German physiologist Theodor Schwann, formulated the cell theory. He investigated plants microscopically and conceived that plants were made up of recongnizable units, or cells. Schleiden published his cell theory on plants, his friend Schwann extended it to animals, thereby bringing botany and zoology together under one unifying theory. Rudolf Virchow
1855 Virchow is credited with multiple important discoveries. Virchow's most widely known scientific contribution is his cell theory, which built on the work of Theodor Schwann. He is cited as the first to recognize leukemia cells. He was one of the first to accept the work of Robert Remak, who showed that the origins of cells was the division of preexisting cells. He did not initially accept the evidence for cell division, believing that it only occurs in certain types of cells. When it dawned on him that Remak might be right, in 1855, he published Remak's work as his own. Referred to as "the father of modern pathology," he is considered one of the founders of social medicine. August Weismann
1892 August Weismann was a German evolutionary biologist. His main contribution was the germ plasm theory, according to which (in a multicellular organism) inheritance only takes place by means of the germ cells - the gametes such as egg cells and sperm cells. Other cells of the body - somatic cells - do not function as agents of heredity. Weismann's work on the demarkation between germ-line and soma can scarcely be appreciated without considering the work of (mostly) German biologists during the second half of the 19th century. This was the time that the mechanisms of cell division began to be understood. Eduard Strasburger, Walther Flemming, Heinrich von Waldeyer and the Belgian Edouard Van Beneden laid the basis for the cytology and cytogenetics of the 20th century. Strasburger, the outstanding botanical physiologist of that century, coined the terms nucleoplasm and cytoplasm. Sofija & Kinga