More About – The Cell
Now, as we know that ‘biology‘ is the branch of science that deals with the study of living organisms, even if we break the word ‘biology’ and find out its meaning, it is ‘bio – life and logy – study’. With the diversity in living organisms in each and every aspects, we found one common feature in all of them and that is “life”.
Approximately there are 10 millions of living species present on the Earth till date and still more to be found. These all have variations in their shape, size, colours and life expectancy.
Henceforth, if there is a life, then these organisms have the immense capability to give birth to their young ones and continue their existence on Earth. This remarkable process continues when the organisms reproduce within its own species and giving birth to their progeny.
Life exists, because of the existence of the one basic unit and that is “the cell“. It is the smallest independent element, responsible for producing energy, individual growth, reproduction and other chemical functions and hence termed as the ‘building blocks of life’.
Discovery of Cell
In the year 1665, Robert Hooke was the first one to discover the cell. He took a bottle cork and used a compound microscope having very ‘low magnification’ to observe the tiny compartments and named it “Cells”. He was unable to observe the internal structure of the cell and did not come to any more conclusions.
Later, another scientist named, Antonie van Leeuwenhoek, observe the cell of bacteria, protistans and bacteria under the improved microscope which was of higher magnification power. Through this microscope, he found that these objects (cell) are motile (moving) and concluded that these units are “alive”.
In 1883, Robert Brown provide the details of the structure of a cell and describe the nucleus.
The ‘cell theory’ was given by the two scientists, ‘Theodor Schwann and Matthias Jakob Schleiden‘. They gave three postulates, which were:
1. The cell is the smallest, fundamental and functional unit of life.
2. All organisms are made up of one or more cells.
3. The continuity of life exist directly from the growth and division of the single cell.
Later on, Rudolf Virchow added, “All cells arise from the pre-existing cells”.
Modern Cell Theory
Researchers, scientist, biologist though accepted the cell theory, but still, they know that there are many more features to gather about the cell, and few of them are listed below which are been accepted till now:
- All cells derive from the division of the pre-existing cells.
- The cell is the structural, functional and elementary unit of life.
- Energy flow – metabolism and biochemistry also occur within the cell.
- Cell contains the genetic information in the form of DNA passed that is been transfer from one organism to another of the similar species, and this happens during the cell division.
- All living organisms composed of one or more cells.
- Cell can be unicellular – that have only one cell or they can be multicellular – that have multiple cells in a body.
- All the work performed by an organism depends on the combined efforts of the cells of the individual.
Although there are lots of controversies related to the cell theory, as the viruses do not have cells and still they are able to survive.