Development of Cell Theory Chapter 1 Development of Cell Theory

Science Dictionary Spontaneous generation (abiogenesis): Biogenesis: Cell: Basic structural and organization unit of living things.

Importance of the cell The cell is the basis for life. The human body is made up of 100 trillion cells all working together. Cells are specialized to perform different tasks, i.e. bone cells, muscle cells, nerve cells etc... ~100 years ago people wrongly believed in abiogenesis (living things from non-living items)

A brief history… ok, not so brief… Up to ~100 years ago, the science world believed that non-living things had the ability (given the right circumstances) to change into living things. Eels made from ooze in ponds Frogs and fish from clouds in the sky Maggots from rotting meat Mice from sweaty shirt & straw

The Paradigm Shift This seemingly ridiculous idea is known as spontaneous generation: the belief that living things are created from non-living things. Most scientists and general public firmly believed this to be true, however, there were a few scientists who questioned how this could happen. They tried to prove spontaneous generation to be false but noone would believe them. Something was always “wrong” with their experiments to discredit them.

Then, Francesco Redi devised an experiment that could not fail. With a series of glass jars, wire mesh and rotten meat he proved once and for all that living things (flies) were responsible for the appearance of maggots, not a non-living entity (air).

After Redi’s experiment spontaneous generation was dropped and the theory of biogenesis prevailed. Biogenesis: living things are created from other living things of the same kind.

History of Microscopes Magnification (making things appear bigger) has been used for thousands of years. From the time of the Egyptians (1000BC) glass lenses have been used to see the microscopic world. From increasing technology and resolution “cells” were discovered and led to the development of modern cell theory.

History Robert Hooke -First to see cells, was looking at cork. (1665) Anton van Leeuwenhock - Observed living cells (1673) Theodore Schwann – animals have cells (1839) Mattias Schleiden – plants have cells (1845) Rudolf Virchow - every living thing has cells. Predicted that cells come from other cells. (1850 )

Cell Theory All organisms are made of cells All cells arise from pre-existing cells The cell is the basic unit of life

History Late 1600’s -Robert Hooke- looked at cork under microscope, coined the term “cells” -Leeuwonhoek- saw living cells including bacteria 1824- Henry Dutrochet- all living things made of cells 1831- nucleus first named 1838- Schleiden, all parts of plants made of cells 1839 -Schwann , animals made of cells 1855- Rudolph Virchow- stated all cells arise from pre-existing cells