Spontaneous generation

Proving and disprovingThe Origin of Life

350 BC Aristotle Greek

He was a philosopher. He can about his ideas by thinking not experimenting.

Life arose from non living matter by spontaneous generation

1600 AD Van Helmot German

• Published the recipe for the spontaneous generation of mice.

• Place old rags in the corner of your attic.• Sprinkle it with bread crumbs and seeds• Voila (Hier) baby mice

1665 Robert Hooke English

• Coined the word “Cells” by looking at a cork through a microscope.

• He thought they looked like the little rooms or Cells that monks lived in.

1668 Francesco Redi ItalianCasts doubt on spontaneous generation by discovering the life cycle of the fly.

They didn’t know that maggots were Fly larvae.

1675 Anton van Leeuwenhoek Dutch

Discovers microorganisms “animacules”With the first microscope.

Draws bacteria.

1748 John Needham Scottish

Supports spontaneous generation of organisms

1. Boiled broth 1 min.2. Sealed with loose cork3. Bacteria still grew4. Therefore Spontaneous generation must be true

1776 Lazaro Spallanzani Italian

Rejects Needham’s experiment. He said it was a bad procedure.He redid the experiment.

1. Boiled the broth for 20 min.2. Sealed flasks with glass tightly3. No micro organisms appeared.4. Therefore Spontaneous

generation does not occur.

1820 Ignaz Semmelweis Austrian

Discovered that washing hands in hospital Prevents infections andSaves lives.

People didn’t believe him

The Cell Theory

• The next 4 scientists each made discoveries about cells.

• Together they create what we now call the cell theory.

1835 Félix Dujardin French

Microorganisms are, in fact, Cells

1838 Schleiden & Schwan German

1.Matthias Schleiden discovered

All Animals are made of Cells

2.Theodor Schwann discovered

All Plants are made of cells

1858 Rudolf Virchow German

All cells come from other cells

1861 Louis Pasteur French

1.Rejects spontaneous generation , Once and for all.

2.Discovers that microorganisms cause disease.

Pasteur’s experiment1. Boil broth for 20 min.2. Make a swan neck tube.3. If bacterial growth comes from dust in the air,then the dust will get trapped in the s bend and contamination will not occur. 4. If bacterial growth is spontaneous but need a “factor” from the air circulating, then contanination will occur.5. 150 years later there is still no contamination. Spontaneous generation does not exist

6. When the tube broke or the liquid touched the neck,Then the broth became contaminated immediately.

1862 Sad News

• Semmelweis dies of an infection

1870 Thomas Henry Huxley English

Theory of “Biogenesis”All life comes from life

Can any of you see a problem with this theory?What question comes to mind?

1928 Alexander Flemming English

Mold inhibits bacterial growth

Penicillin stops diseases.

And the discoveries continue......