Study of cell

Cell

Cell is the basic structural and functional unit of life.
»   The word 'cell' was first coined by British scientist Robert Hook in the year 1665.
»   Study of cell is called cytology.
»   The smallest cell is Mycoplasma gallisepticum.
»   The longest cell in human body is Neuron.
»   The biggest cell is egg of Ostrich.
»   Schilden and Schwan established cell theory in the year 1838-39

Main features of the cell theory
1. All organism are composed of cell.
2. Body of every organism is made of cell.
3. Each cell arises from pre-existing cell.
4. Every organism starts its life from single cell.

Types of Cell

1. Prokaryotic cell
These are primitive cell having three basic structure f typical cell but lack nuclear membrane. Nuclear material is present in a region of cytoplasm called nucleoid. Other membrane bound organelles are absent such as mitochondria, lysosome, golgi bodies etc. Ex.-Virus, bacteria and cynobacteria are Prokaryotes.
»   Number of Mitochondria in bacterial cell is zero.
»   The smallest known prokaryotic organism is Mycoplasma.

2. Eukaryotic cell
These are complete cell which contain membrane bound organelles and nucleus. Unicellular and multicellular plant and animal have Eukaryotic cell.
»   The biggest single called organism is Acetabularia.
»   Nucleus contain chromatin made up of DNA and histone protein.
»   Nucleolus is present inside nucleus.

Difference between Prokaryotes and Eukaryotes Cell