1. Section14.2

2. Example #1
Observation: Every year in the spring, the Nile River flooded areas of Egypt along the river, leaving behind nutrient-rich mud that enabled the people to grow that year’s crop of food. However, along with the muddy soil, large numbers of frogs appeared that weren’t around in drier times

3. Example #1
Conclusion: It was perfectly obvious to people back then that muddy soil gave rise to the frogs

4. Example #2
Observation: In many parts of Europe, medieval farmers stored grain in barns with thatched roofs (like Shakespeare’s house). As a roof aged, it was not uncommon for it to start leaking. This could lead to spoiled or moldy grain, and of course there were lots of mice around.

5. Example #2
Conclusion: It was obvious to them that the mice came from the moldy grain.

6. Example #3
Observation: In the cities centuries ago, there were no sewers, no garbage trucks, no electricity, and no refrigeration. Sewage flowed down the streets, and chamber pots and left over food were thrown out into the streets each morning. Many cities also had major rat problems and a disease called Bubonic plague.

7. Example #3
Conclusion: Obviously, all the sewage and garbage turned into the rats.

8. Example #4
Observation: Since there were no refrigerators, the mandatory, daily trip to the butcher shop, especially in summer, meant battling the flies around the carcasses. Typically, carcasses were “hung by their heels,” and customers selected which chunk the butcher would carve off for them.

9. Example #4
Conclusion: Obviously, the rotting meat that had been hanging in the sun all day was the source of the flies.

10. I. Spontaneous Generation The idea that life can come from non-life
F. Redi (Italian scientist) 1668
Disproved it with his experiment
Flies and maggots did not magically appear from rotting meat
Fig p. 401

12. II. Theory of Biogenesis
Only living organisms can produce other living organisms
Louis Pasteur
Fig p. 402
How did Pasteur’s experiment support biogenesis?
Microorganism only grow when they ____________________

14. III. Primordial Soup Hypothesis
Oparin & Haldane (1920’s)
Organic molecules could have been made from simple reactions, if Earth’s early atmosphere had a mix of certain gases
Energy provided by the Sun and lightning

16. Urey & Miller (1953)
4. Built a glass apparatus to simulate Earth’s early conditions
Fig p.403
5. What were the products of this experiment?
Organic compounds, including amino acids

17. 6. How did it support the primordial soup hypothesis?
It explains how amino acids could have been created
7.Organic reactions could have began in deep sea hydrothermal volcanic vents

18. Amino Acids  Make Proteins Coding system for protein production
IV. Required steps (p. 404)
Amino Acids  Make Proteins
Coding system for protein production
RNA was probably the first coding system

19. V. First Cells
Prokaryotes
This means they ………
Archaea are closest relatives of Earth’s first cells
Extreme environments
Hot springs or deep sea volcanic vents
Fig p. 405

20. Photosynthesizing prokaryotes
Autotrophic
This means they……
Do not need the Sun’s energy or oxygen
Obtain energy from sulfur
Photosynthesis gives off oxygen (waste)
Oxygen levels increased
Formed ozone layer
Conditions became right for eukaryotic cells

21. Endosymbiont Theory
Lynn Margulis (1966)
The ancestors of eukaryotic cells lived closely with prokaryotic cells.
Prokaryotes might have lived inside eukaryotes.
Mutually beneficial relationship

22. 5. Over millions of years: (Fig. 14.17)
a) aerobic prokaryotes became mitochondria
b) photosynthetic bacteria became chloroplasts
c) Evidence → mitochondria and chloroplasts contain their own circular DNA and reproduce by fission just like prokaryotes

24. There are still a lot of unknowns about the origin of early life
This is different than evolution
We will be looking at evidence for evolution next week 