The three fundamental propositions of classical cell theory are that the cell is the most basic unit of life, all life is made up of cells and cells are formed only by other cells. Each tenet of this theory is important to understanding the way living things function on every level.Know More
The first proposition, that the cell is the most basic component of living things, can be observed directly. Single-celled organisms are well known and may comprise the bulk of Earth's living biomass. Any unit, such as a tissue, that can be broken down still further cannot be regarded as basic. Units more simple than a cell, however, cannot truly be said to be alive. A cell's organelles, for example, function only in the context of their cellular environment.
From this it follows that all life must be made up of cells. Cells build tissues, tissues make organs, organs are organized into systems and these systems make up the bodies of organisms. Across the domains of life, whether eukaryotic or prokaryotic, all living things can be described in terms of their cells.
Finally, the cell theory posits that the origin of a living cell must be a result of the action of another living cell. Cells do not spontaneously form, and they are too complicated to self-assemble.Learn more about Cells
Cell theory states that all living organisms are made up of cells and that the cell is the basic unit of life. It also states that all cells arise from preexisting cells. The formulation of this theory is not attributed to Anton van Leeuwenhoek, but his pioneering work with microscopy was essential in its development.Full Answer >
Cell are considered the basic unit of life because all life forms are composed of them. Some forms of life are made of one cell; others contain trillions.Full Answer >
The three scientists who formulated cell theory were Theodor Schwann, Matthias Jakob Schleiden and Rudolf Virchow. Schwann and Schleiden worked together to formulate the theory in 1838, and Virchow contributed to the theory in 1858.Full Answer >
The way in which a cell responds to contact with other cells depends on the function and activity of both cells. Most normal cells cease division if they come into contact with other cells; however, cells of the immune system interact directly with pathogens or foreign organisms to destroy them.Full Answer >