Student Question

What are 2 exceptions to the cell theory and why are they exceptions?

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There are three basic “rules” that tend to be universally accepted as parts to the cell theory. These “rules” are identified below:

  1. Cells are the basic fundamental unit of structure, function, and organization in all living things.
  2. New cells are formed and come from other cells. (In other words, cells produce cells.)
  3.  All living things are made of cells.

Some resources indicate that the following modern addendums have been added to the basic cell theory.

  1. The cells within individuals of the same species are basically the same in chemical composition.
  2. Some organisms are made of only one cell. Unicellular is the term used to define such organisms. 
  3. Other organisms are multicellular and are made of many cells.
  4. Heredity information (DNA) is passed from parent to daughter cells during reproduction.

However, there are some exceptions to the cell theory. Each exception violates rule number 2 of the basic cell theory that is explained above. Three exceptions are identified below.

  1. There is a debate as to whether or not viruses should be considered to be alive. The debate results from the fact that viruses cannot reproduce on their own. They must invade a host cell and utilize the host’s genetic material in order to reproduce.
  2. The first cell did not come from another cell.
  3. Mitochondria and chloroplasts have their own genetic material and can reproduce independently from the cell in which they reside.

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