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.
Note: The second possibility is to go deep into the specialty, that is, to rise to the next step of the educational ladder – this is the magistracy. For students of the master’s program there is a program that deepens the knowledge already available. Formally, one can apply to a completely new specialty: for example, to study at the bachelor’s degree in economics and enter the magistracy for radio engineering. I’ll have to hand in just one profile subject, but why? It turns out that your level of knowledge in this area will be an order of magnitude lower than necessary, because the master’s program is the second stage of education. Depending on the chosen field of activity, the Master’s program can be either useful or necessary. It will be necessary, for example, for future teachers, because without a magistracy they will not be able to get a job in many institutions. The third way that you can move after receiving a diploma is to get a second higher education in any specialty of interest. This way there are students who want to expand their area of competence, as well as those who made a mistake with the choice of their first education.