1. Origin of Life
Chapter 12.3 and 12.4

2. Defining Life What is life? Living things are made of cells.
Living things obtain and use energy. 
Living things grow and develop.
Living things reproduce.
Living things respond to their environment. 
Living things adapt to their environment.

3. Early Life Likely formed around 3.5 – 3.8 billion years ago.
Stromatolites were ancient microscopic organisms found in stacks of sediments. Have been dated to about this age
Earth is about 4.5 billion years old
Universe is about 15 billion years old

4. Early Thoughts Spontaneous Generation Popularized by Aristotle
Was believed until the 1700s!!!!
Redi was credited for performing the first experiments that refuted these ideas.
Further confirmed by

5. Louis Pasteur
Performed early experiments disproving the idea of spontaneous generation
His experiments showed how heat could kill bacteria and prevent fermentation.
Has been widely utilized to make foods more shelf-stable and last longer.

6. Sample 1: heat kill bacteria in sample, long neck of flask prevents air carrying bacteria into the solution. No growth
Sample 2: heat kill bacteria in sample, long neck of flask is removed allowing air that carries bacteria to mix with solution. Growth occurs
Sample 3: heat kill bacteria in sample, long neck of flask is tipped and exposed to the bacteria in the air. Growth occurs.

7. Oparin Said earth likely had a “reducing atmosphere”
The Amazing Oparin
Thinks Oparin is awesome
Said earth likely had a “reducing atmosphere”
He said earth has some basic chemicals in place, (H2, CO, NH3, H20) but no O2
Supported the claims of a “primordial soup”

8. Miller and Urey
Using the ideas of Oparin they designed a simple experiment that showed the development of amino acids. (organic molecules)
These amino acids could self-replicate and later form early life.
Was a bit of an eureka moment.

9. Missing Oxygen Gas
Geothermal energy aplenty
Found Amino Acids

10. Margulis
Said life likely became more complex from symbiotic mergers of bacteria.
Really supports the idea that some of the earliest lifeforms were much like mitochondria and chloroplasts that were later adapted to work together with other larger lifeforms
(Could also have been helped if we traveled from another place)

11. Endosymbiotic Theory Simple steps:
Prokaryotic cells’ membranes start to fold inward making first eukaryote
Simple aerobic bacteria fits inside of new cell
Simple photosynthetic bacteria fits inside of new cell
These bacteria become today’s mitochondria and chloroplasts

15. Evidence of Endosymbiosis
There are many similarities between cyanobacteria and chloroplasts. They seem to share many parts and purposes. This supports the idea that modern day chloroplasts were likely directly descended from very old cyanobacteria. This support the idea of endosymbiotic theory.