Overview
This lecture covers the quirky history and major contributors to the development of the cell theory, a foundational concept in biology.
The Three Parts of Cell Theory
- All organisms are made of one or more cells.
- The cell is the basic unit of structure and organization in organisms.
- All cells arise from preexisting cells.
Early Microscopes and Discoveries
- Zacharias Janssen is credited by some with inventing the first compound microscope in the early 1600s.
- Anton van Leeuwenhoek built his own microscope and discovered bacteria by examining dental scrapings.
- Leeuwenhoek called these microbes "animalcules" because they looked like tiny animals.
Robert Hooke and the Naming of the Cell
- Robert Hooke observed cork under a microscope and named the tiny chambers "cells."
- Hooke's scientific contributions were overshadowed by a feud with Isaac Newton, leading to much of his work and only portrait being lost.
Development of Cell Theory in the 1800s
- Matthias Schleiden concluded all plants are made of cells by studying plant specimens.
- Theodor Schwann found that all animals are made of cells and collaborated with Schleiden.
- Schwann is also known for identifying a type of nerve cell ("Schwann cell") and inventing rebreathers for firefighters.
Controversy and Finalization of the Theory
- Schleiden believed cells formed spontaneously ("free-cell formation").
- Rudolph Virchow, drawing on Robert Remak's research, established that all cells arise from preexisting cells.
- Disputes and "borrowed" research surrounded the third part of the cell theory.
Key Terms & Definitions
- Cell Theory — The principle stating all organisms are made of cells, the cell is the basic unit, and cells come from preexisting cells.
- Microscope — An instrument used to view very small objects, such as cells.
- Animalcules — Name used by Leeuwenhoek for microscopic organisms (now known as bacteria).
- Schwann Cell — A type of nerve cell named after Theodor Schwann.
Action Items / Next Steps
- Review the three parts of cell theory.
- Research more about the contributions of Hooke, Leeuwenhoek, Schleiden, Schwann, and Virchow.