1. Cell Biology – GERM THEORY
Integrated Science 1-2
Cell Biology – GERM THEORY

2. A. Cell Theory – What We Think Today
I. All life is cells
II. All cells come from other cells

3. B. We used to think
Small organisms appear in non-living matter when conditions are right
Spontaneous Generation:
Maggots and flies from rotten meat
Frogs from pond mud
1600’s: Jan Baptiste van Helmont:
Mice from wheat grains placed in a sweaty shirt!
Jan Baptiste
van Helmont

4. B. We used to think III. 1668 – Francisco Redi
1. Maggots don’t form in rotten meat if flies are kept away!
Wire
screen
meat
flies
maggots

5. B. We used to think IV. Lazzaro Spallanzani
Meat broth boiled & sealed never spoils!
Broth boiled & left open to air develops microorganisms
heat
Mold and
bacteria

6. B. We used to think IV. 1750 Lazzaro Spallanzani
… but critics claimed that a “vital principle” in air is needed for spontaneous generation, and was “destroyed” by boiling.
V – Louis Pasteur settles the matter! (you will too!)
Louis Pasteur

7. Germ Theory: Ignaz & Louis In ACTION The Experiments!
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Start 1:30 in

8. C. How did life on Earth begin?
I. We know today that ALL life shares one Precambrian ancestor (all life uses the same genetic code.)
1. If life never starts spontaneously, how could it begin the first time??
2. Divine creation? Extraterrestrial origin? From non-living chemicals?
(we don’t know…)

9. C. How did life on Earth begin? II. Blue-green algae
~3,500,000,000 –year old cyanobacteria
(blue-green algae)

10. C. How did life on Earth begin? II. Blue-green algae
IS 1-2 Disease Unit - Cell Biology/Germ Theory

11. C. How did life on Earth begin? III. 1953: Stanley Miller & Harold Urey
Pre-Cambrian Air
H20
NH3
CH4 H2
Heat - Boil
Electricity
Amino acids out! (The building blocks of proteins)

12. Animation of Experiment

13. Stanley Miller

14. The same mix of amino acids were found next year in the Murchison Meteorite…