The cell theory is a fundamental principle in biology that describes the properties and functions of cells, which are the basic building blocks of all living organisms. It comprises three main components:
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All living organisms are composed of one or more cells: This asserts that cells are the smallest units of life and that they make up the structure of all living things, whether unicellular (like bacteria) or multicellular (like plants and animals).
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The cell is the basic unit of structure and organization in organisms: This indicates that cells not only serve as the basic unit of structure but also play a critical role in the functionality and organization of living entities. Each cell contains various structures (organelles) that contribute to its specific functions.
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All cells arise from pre-existing cells: This principle emphasizes that new cells are generated through the division of existing cells, highlighting the continuity of life and the importance of cellular reproduction. It underscores that cells cannot spontaneously generate; rather, they are produced through a cellular lineage.
Together, these three tenets form the foundation of modern biology, providing insight into the complexity of life and the interdependence of living organisms and their cellular components.