1. Origin of Life

2. Biogenesis vs. Abiogenesis
Biogenesis is the idea that living things come from other living things like themselves.
Abiogenesis is the idea that living things come from nonliving things.

3. Ways that abiogenesis were disproven
Numerous tests were performed to disprove the idea of abiogenesis.
These tests were performed by Franscisco Redi and Louis Pasteur.
Redi
Pasteur

4. Redi’s Experiment
Performed his experiment prior to the invention of microscopes.
Prior to Redi’s experiment, people believed flies were generated spontaneously from rotten meat.

5. Redi’s Experiment Let’s look at this experiment
Started off with fresh meat in two different jars.
He placed netting over one of the jars.
He left one of the jars open.
Which jar of had maggots on the meat?
The one without the nets.

6. Why did the open jars of meat have maggots?
Adult flies were able to land on the meat in the open jars to lay their eggs. They could not get to the meat in the jar that was covered with net.
VS.
Jar without netting
Jar with netting

7. Redi’s Conclusion The maggots came from the eggs laid by the flies.
Let’s try this ourselves. 
_pasteur_experiment/index.html

8. Pasteur’s Experiment
His experiment was based on another experiment that concluded that microorganisms travel in air.
Pasteur’s Equipment
Flask with an “S” shaped neck.
The shape of the neck prevented air from falling straight down into the container.
Broth – This is like the liquid part of soup. This would give micoorganisms a place to grow if they were there.
Heat source – Pasteur used this to heat the broth when he was sterilizing it.

9. Pasteur’s Experiment Let’s look at what Pasteur did…..
Placed broth in two different Swan flasks.
He heated both of them.
He broke the stem off one of the flasks.
Which flask became cloudy?
The one with the broken stem.

10. Pasteur’s Conclusion
Solid particles, such as dust, in the air transport the microorganisms.
Lets try this ourselves!! 
di_pasteur_experiment/index.html

11. The Early Earth and First Organisms

12. The Early Earth…… what was it like?
The atmosphere was very different.
There was NO oxygen.
Too hot for liquid water.
Once the surface of the Earth cooled, volcanoes formed and erupted.
Then the Earth cooled. Thunderstorms drenched the earth and the oceans formed.
The primitive Earth atmosphere is hypothesized to have consisted mostly of hydrogen, methane, ammonia and water vapor. O2

13. +  Oparin’s hypothesis
Oparin hypothesized that life began in the oceans of early Earth.
Stated the following:
Sun
Heat from Earth
Lightning
Organic Compounds formed in the ocean
Gases present in air (NH3, CH4, H2 and H2O vapor) + 

14. Miller and Urey’s Experiment
Tested Oparin’s Hypothesis
Their set up contained the following:
Gases hypothesized to be present in the early atmosphere
Electricity
Heat (in the form of boiling water)
Miller and Urey were attempting to prove that complex organic compounds could have been formed in the oceans of early Earth.
Discovered that amino acids were formed

15. Miller and Urey’s Experimental Setup

16. Who could use these organic compounds?
Anaerobic prokaryotes could have!!!
Thought to be the first type of living organisms.
There was no oxygen present in the atmosphere  ANAEROBIC
Used organic compounds in the ocean as their food source.
These cells were prokaryotic.
No nucleus
No membrane bound organelles
Did have DNA
Did have ribosomes to make proteins

17. And then……. Photosynthetic Prokaryotes
Thought to be the second type of living organism
Carried out photosynthesis
CO2 + H Light  C6H12O O2
This released oxygen into the atmosphere.
These organisms were needed so that all of the other forms of life could evolve. Why?
OXYGEN WAS NOW PRESENT IN THE ATMOSPHERE!

18. What next…… The aerobic prokaryotes were the next to appear on Earth.
These were the first organisms to utilize aerobic respiration.

19. And lastly…… Eukaryotic cells appeared!!! These cells have….
A true nucleus
Membrane bound organelles
The Endosymbiotic Theory explains how eukaryotic cells were formed.

20. Endosymbiotic Theory Let’s take a closer look at this….
A larger cell engulfed a smaller photosynthetic prokaryote  Chloroplasts.
A larger cell engulfed a smaller aerobic prokaryote  Mitochondria