The cell is the basic structural, functional and biological unit of all known living organisms. Cells are the smallest unit of life that is classified as a living thing, and are often called the "building blocks of life". Discoverer:
The cell was discovered by Robert Hooke in 1665. The cell theory, first developed in 1839 by Matthias Jakob Schleiden andTheodor Schwann, states that all organisms are composed of one or more cells, that all cells come from preexisting cells, that vital functions of an organism occur within cells, and that all cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells. Cells emerged on Earth at least 3.5 billion years ago. Cell Theory:
In biology, cell theory is a scientific theory that describes the properties of cells, the basic unit of structure in every living thing. The initial development of the theory, during the mid-17th century, was made possible by advances in microscopy; the study of cells is called cell biology. Cell theory is one of the foundations of biology. The three parts to the cell theory are as described below:
All living organisms are composed of one or more cells.
The cell is the basic unit of structure, function, and organization in all organisms. All cells come from preexisting, living cells.
There are over 200 different types of cells within the human body. These cells all vary in size, shape and diameter. Most cells range between ten and fifteen micrometers in diameter, however, some cells, such as the human egg cell, are much larger than this, with a diameter of roughly 100 micrometers. The human eggs cell is just barely visible to the naked eye. Some of the longest cells include nerve cells, which can be as long as a meter, but are so thin; they are invisible to the naked eye. Cells, although they range in size and shape, cannot become too large, or they may become unable to support their own...
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