The cell is the structural and functional unit of all living beings. The cell was discovered by the British scientist Robert Hooke in 1665. He was the first to see tiny blocks in slices of cork through a microscope. He gave them the name “cells” which means“small rooms” in Latin.
Later, it was discovered that all plants and animals consist of cells. In the 1830s German researchers, Matthias Schleiden and Theodor Schwann, came to the conclusion that plant cells and animal cells have the same structure and that the cell is the basic unit of any living tissue. Their discovery led to the creation of The Cell Theory which states that:
• The cell is the unit of structure, physiology, and organization in living things.
• All cells are basically the same in structure, chemical composition and vital functions.
• All new cells come from pre-existing cells by division.
Every living being has from one to trillions of cells. Tiny amoebas are one celled organisms and a human body contains trillions of cells. Cells form different tissues and organs and therefore have different purposes. For example, blood cells and muscle cells don’t look like each other very much (see picture 1) because their functions are different. However, according to The Cell Theory their structures are quite similar and they consist of the same basic elements.
• The structure of plant cells differs a lot from the structure of animal cells.
• If an organism has only one cell it can still be defined as a living being.
• The Cell Theory states that epithelial (skin) cells are absolutely identical to osteocyte (bone) cells.