What is Cell? – Definition
Cell is a basic, structural and functional unit of life of plants and animals.
It is a unit of biological activity delimited by a semi permeable membrane and is capable of self reproduction.
The word cell comes from the Latin word cellula, meaning, a small room. The term was coined by Robert Hooke in a book he published in 1665, when he compared the cork cells he saw through his microscope to the small rooms monks lived in.
Any cellular organism may contain only one type of cell from following two types of cells.
- Prokaryotic cell
- Eukaryotic cell
Difference between prokaryotic and eukaryotic cell can be read on the page. Here, distinction between these two types for some of the important points are summarized.
Organisms may be Unicellular or Multicellular.
| Unicellular Organism | Multicellular Organism |
|---|---|
| Any living being consisting of a single cell. | Organisms consisting of more than one cell, and having differentiated cells that perform specialized functions. |
| Examples – bacteria, archaea, protozoa, unicellular algae, and unicellular fungi or yeasts. | Examples – All members of the kingdoms Plantae and Animalia (exception Myxozoans) |
Exceptions to Cell theory
There are some exceptions to cell theory. These are as below
- Viruses
- Vaucheria (alga)
- Rhizopus (fungus)
Another must read concept in cell is its division, Somatic cell division and Gametic cell division.