From Spontaneous Generation to the Modern Cell Theory

Spontaneous generation, also known as Abiogenesis, was the belief that living organisms were produced/generated from nonliving sources.

Examples:- Frogs came from mud- Mice arose from sweaty clothing- Flies came from decaying meat.

Spontaneous Generation

Francesco Redi - 1668 (Italian Physician and Poet)

Attempted to disprove spontaneous generation by proving that maggots did not mysteriously generate from decaying meat

Conducted an experiment where he placed rotting meat in two different jars. One was open to the air allowing insects to enter and the other was covered preventing insects from entering the jar.

The meat in the covered jar did not produce maggots.

·Disagreed with Needham claiming that Needham didn't seal his jars well enough. (Microbes came from the air)·Attempted to disprove Needham by repeating his experiment but with two changes:·boiled flasks longer, and ·SEALED THEM after boiling by fusing the glass tops shut·Result: NO growth in ANY flask

Spallanzani - (Italian Naturalist)

Louis Pasteur

Used a swan neck flask to once and for all disprove the theory of abiogenesis.

Pasteur in his experiment ensured that the only variable effecting the broth were the microbes in the air.

With the disapproval of spontaneous generation came the theory of biogenesis - LIFE produces LIFE.

Cell Theory

Anton vanLeeuwenhoek - invented the first microscope.

Robert Hooke - looked at slices of cork with a microscope and saw small compartments which he called cells.

Schleiden and Schwann - discovered that animal and plant tissues were composed of cells - proposed the modern cell theory

Cell Theory

1) The cell is the basic structural unit of life.

2) The cell is the basic functional unit of life.

3) All cells come from preexisting cells.