notes on the cell for IXth class
Answers
Explanation:
Revision Notes on The Fundamental Unit of Life
Quick Review
All living organisms in this universe are made up of cells.
They either exist as a single cell or as a combination of multiple cells.
Discoveries about Cells – The Fundamental Unit of Life
Discovered By Period of time What they discovered?
Robert Hooke 1665
noticed the presence of cells in a cork slice
Leeuwenhoek 1674
found the presence of living cells in the pond water
Robert Brown 1831
recognized the existence of a nucleus in the cell
Purkinje 1839
invented the term ‘Protoplasm’ which is the liquid present in a cell
Schleiden and Schwann 1838, 1839
presented the cell theory that all organisms are actually made up of cells
Virchow 1855
suggested that all cells come from cells that already exist in nature
The Cell Theory
1. A cell is the structural and functional unit of all living organisms.
2. All the living organisms are made up of cells.
3. Cells are formed from pre-existing cells.
Unicellular Organisms – The organisms that consist of a single cell such as Amoeba.
Multicellular Organisms – The organisms which contain various cells that perform different functions in the organism such as plants fungi and animals
How can multicellular organisms originate from a single cell?
A cell has the capability to divide itself into cells of its own type. Therefore, more cells can generate from an already existing cell.
The Shape of the Cell
The shape of the cell may vary depending upon the type of function they perform in an organism.
Cells are capable of changing their shape. For example, the white blood cells and amoeba can change shapes on their own.