Cell Theory
Page 8: History of Cell
Robert Hooke examined a piece of cork and found little structures in it which he compared to cellulae
These structures were named "cells"
Later discovered that the cells found in the cork were actually outer walls of former plant cells
Zacharias Janssen invented the microscope in 1608
Anton van Leeuwenhoek examined different subjects using a refined microscope and found moving protists and sperm, which he called "animalcules"
Page 13: The Cell Theory
The Cell Theory is one of the basic principles of biology
The three main principles of the Cell Theory are:
The cell is the basic unit of life
All living organisms are composed of cells
New cells are created from pre-existing cells
Page 14: 1st Postulate: Cell is the basic unit of Life
In order for an organism to be considered living, it must have a cell
Movement of organelles inside a cell is proof that an organism is alive
Page 15: 1st Postulate: Cell is the basic unit of Life
In the cork examined by Hooke, the protoplasm of the cell had already dissipated, indicating the cell's death
Leeuwenhoek observed animalcules shooting and spinning inside the cells of his teeth scrapings
Page 16: 2nd Postulate: All living organisms are composed of cells
Matthias Jacob Schleiden established that plant specimens are composed of cells
Theodore Schwann discovered that animals are also composed of cells
Page 17: 3rd Postulate: New Cells are created from preexisting cells
Rudolf Virchow introduced the third tenet of the cell theory: "Omnis cellula e cellula" which means "Cells come from pre-existing cells"
Page 19: Development of Cell Theory
Zacharias Janssen invented the objective microscope in 1590
Robert Hooke viewed a thin slice of cork with a primitive microscope in 1663-1665
Marcello Malpighi and Nehemiah Grew conducted separate investigations on plant cells and determined the presence of organelles within them
Page 21: Development of Cell Theory
Anton van Leeuwenhoek upgraded Janssen's microscope and discovered mobile organelles in many subjects, which he called animalcules
Page 22: Development of Cell Theory
Robert Brown discovered the nucleus in 1831
Matthias Schleiden recognized that plant parts come from cells and proposed that the different structures of a plant are all composed of cells
Page 24: Development of Cell Theory
Theodore Schwann declared that animals are likewise composed of cells, ending the debate about the structural origin and composition of plants and animals
Albrecht von Roelliker stated that sperm and egg are composed of cells and that all humans are configured from cells
Louis Pasteur proved that bacteria are able to multiply and that bacterial cells come from other bacterial cells
Page 26: Development of Cell Theory
Rudolf Virchow declared "Omnis cellula e cellula" which means "Cells come from pre-existing cells", completing the cell theory
Page 29: Microscopy: Foundation of Cell Theory
Microscopy started in the 14th century in Italy
Hans and Zacharias Janssen assembled an apparatus with two lenses in one tube
Anton Van Leeuwenhoek created the first compound microscope to observe varied specimens and learn more about cells
Page 33: Transmission Electron Microscope
In 1931, Ernest Ruska and Max Knoll invented the transmission electron microscope, which relied on electrons instead of light
Page 35: Phase Contrast Microscope
In 1932, Fritz Zernike developed the phase contrast microscope (PCM