What is a Cell and Define the Cell Theory
Cell and Cell Theory
In 1665 an English Scientist Robert Hook first studied thin slices of cork and leaves under microscope. He found small boxes like chambers. He called them cells.
In early 19th Century compound microscope was invented. Then Robert Brown discovered nucleus in the cell. Then it was also known that cells have complicated structures.
In 1838 Mathias Schleiden (a German botanist) said that all plants were made up of cells. Then in 1839 Theodre Schwann said that all animals are also composed of cells.
In 1840 J.Purkinji used the term protoplasm for the materials found in the cell.
On invention of electron microscope cell was studies in more detail. The followings are the postulates of cell theory presented by Schleiden and Schwann:
- i) All animals and plants are made up of cells and cell products. These animals and plants may be unicellular or multicellular.
- ii) Cells are structural and functional unit of living organisms.
iii) New cells are formed by pre-existing cells by cell division.
The heroes of your favorite writers will come to life in the minds, so the original versions differ from the translations. For rest and self-development, you need a little – read a few English books. Adapted and unadapted literature Many people find it impossible to start reading in another language. If you want, then it’s quite real! It is impossible to learn a language with a single textbook. Additional reading materials play an important role in proper learning. Adapted books in English (simplified text format) are often more useful than whole chapters of individual textbooks.