Modern Cell Theory

  • Three Main Principles:

    1. All organisms are made up of one or more cells.

    2. Cells are the smallest living units.

    3. Cells arise from pre-existing cells.

Sub-Cellular Particles

  • Exceptions to Cell Theory: Viruses, prions, and viroids are sub-cellular particles that do not have cellular structures.

  • Characteristics of Living Organisms: These particles exhibit some characteristics of living organisms, such as reproduction and transmission of genetic information.

Key Points:

  • The invention of cell theory was significant in the history of biology.

  • The microscope played a crucial role in the discovery and understanding of cells.

  • Cell theory has had a profound impact on various fields of biological research.

  • Sub-cellular particles present exceptions to the first principle of cell theory.