Biology
Introduction of cell
What is cell?
The cell (from Latin cella, meaning "small room") is the basic structural, functional, and biological unit of all known living organism. Cells are the smallest unit of life that can replicate independently, and are often called the "building blocks of life". The study of cells is called cell biology.
Cell Theory
The three tenets to the cell theory are as described below:
- All living organisms are composed of one or more cells.
- The cell is the most basic unit of life.
- All cells arise from pre-existing, living cells.
Matthias Jakob Schleiden
In 1838, Schleiden suggested that every structural part of a plant was made up of cells or the result of cells. He also suggested that cells were made by a crystallization process either within other cells or from the outside.
Theodor Schwann
In 1839, Theodor Schwann states that along with plants, animals are composed of cells or the product of cells in their structures. This was a major advancement in the field of biology since little was known about animal structure up to this point compared to plants. From these conclusions about plants and animals, two of the three tenets of cell theory were postulated.
Rudolf Virchow
In 1855, Rudolf Virchow added the third tenet to cell theory. In Latin, this tenet states Omnis cellula e cellula.
History of microscope
The first microscope to be developed was the optical microscope, although the original inventor is not easy to identify. Evidence points to the first compound microscope appearing in the Netherlands in the late 1500s, probably an invention of eyeglass makers there: Hans Lippershay (who developed an early telescope) and Zacharias Janssen(also claimed as the inventor of the telescope). There are other claims that the microscope and the telescope were invented by Roger Bacon in the 1200s, but this is not substantiated. Giovanni Faber coined the name microscope for Galileo Galilei' s compound microscope in 1625 (Galileo had called it the "occhiolino" or "little eye").
The Inner Life of the Cell
Discussion
Describe your personal impression on cell. Share your opinions with your classmates. Have a short speech in your group on the topic which you are interested in.