Defining Cell Theory
Cell theory is a foundational scientific theory in biology which states that all living organisms are composed of one or more cells, that the cell is the basic unit of life, and that all new cells arise from pre-existing cells.
Section 2: The Three Core Principles
The theory is built on three core tenets, established by scientists in the 19th century. First, all living things are made of cells. Second, cells are the most basic units of structure and function in an organism. Third, all cells are produced from the division of existing cells.
Section 3: A Practical Example
Think of a human being. We are complex, multicellular organisms. According to cell theory, our entire body—from skin to bone to brain—is constructed from trillions of individual cells. Each cell is a fundamental living unit, and every single one of them originated from the division of earlier cells, tracing all the way back to a single fertilized egg.
Section 4: Importance of Cell Theory
Cell theory is crucial because it provides a universal framework for understanding life at its most basic level. It underpins virtually all biological sciences, including medicine, genetics, and evolutionary biology. Understanding that diseases often begin at the cellular level, for instance, is a direct application of this theory.