Cell Theory Notes

Cell Theory is a foundational biological principle stating that all living organisms are composed of cells, the cell is the basic unit of life, and all cells arise from pre-existing cells.

Classical Principles

1. All living organisms are composed of one or more cells: Proposed by Matthias Schleiden and Theodor Schwann.
2. The cell is the basic unit of life: Smallest unit capable of performing all vital life processes.
3. All cells arise from pre-existing cells: Introduced by Rudolf Virchow in 1855.

Modern Principles

• Energy flow occurs within cells.
• Cells contain hereditary information (DNA) passed during division.
• All cells have a similar chemical composition.

History of Cell Theory

• 1665: Robert Hooke observed cork and coined the term "cells".
• 1838-1839: Schleiden and Schwann concluded all plant and animal tissues are made of cells.
• 1855: Rudolf Virchow added that all cells arise from pre-existing cells.