What are the three parts of the cell theory?
Credit:Dan KitwoodGetty Images NewsGetty Images
Q:

What are the three parts of the cell theory?

A:

Quick Answer

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

Full Answer

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

Related Questions

  • Q:

    What is the modern cell theory?

    A:

    The modern cell theory states that living organisms are made of cells, that all cells come from other cells and that cells are the most basic life form. As scientific advancements are made, definitions of theories, like the cell theory, are updated. The modern cell theory is not the same as cell theory of the past.

    Full Answer >
    Filed Under:
  • Q:

    What is a non-living thing composed of cells?

    A:

    Non-living things are not composed of cells, as cells are the smallest unit of life. Small organisms such as bacteria and protists are only composed of a single cell, but are alive.

    Full Answer >
    Filed Under:
  • Q:

    Why is ATP called the energy currency of the cell?

    A:

    ATP is called the energy currency of the cell, and of life, because it is the energy molecule that all cells need in order to do anything within the human body. The molecule is used like a battery within cells and allows the consumption of one of its phosphorous molecules.

    Full Answer >
    Filed Under:
  • Q:

    What is the Hans and Zacharias Janssen Cell Theory?

    A:

    The cell theory states that the cell is the basic unit of life. Hans and Zacharias Jansen greatly contributed to the various parts of this theory by inventing the first microscope.

    Full Answer >
    Filed Under:

Explore