1. ORIGINS Planet earth – 4. 6 bya The first life forms – 3
ORIGINS Planet earth – 4.6 bya The first life forms – 3.5 bya The first eukaryotes – 3.0bya The origin of an oxygen-rich atmosphere – 2.1bya

2. “The Mother of all questions” 1. Not observable 2
“The Mother of all questions” 1. Not observable 2. Even simple life very complex

3. Life…Boiled Down
Self-replicating molecule with a boundary around it that creates internal vs. external environment

4. 4 Problems / Questions
1. How did organic molecules arise from non-organic materials?
2. How were organic monomers assembled into complex polymers?
3. How did the self-replicating molecules needed for inheritance arise?
4. How were the organic molecules packaged into membranes with an internal chemistry different from their surroundings?

5. 1. How did organic molecules arise from non-organic materials?
Miller & Urey (1950)
Attempted to recreate the conditions of primitive earth; believed that earth’s early atmosphere was made up of methane, water vapor, ammonia, and hydrogen gas, so these were the components included in the experiments. Has been repeated many times and yielded similar results. “primordial soup model” ; methane, ammonia, hydrogen, steam  what can out in “soup” at the end was all 20 amino acids commonly found in organisms, along with nucleic acids, several sugars, lipids, adenine, and even ATP (if phosphate was added to the flask)

6. 1. How did organic molecules arise from non-organic materials?
From space?
Panspermia hypothesis

7. 2. How were organic monomers assembled into complex polymers?

8. 2. How were organic monomers assembled into complex polymers?
Transition metals can lend and take away electrons from molecules
A combination of transition metal elements (copper, nickel) and ligands (small organic molecules) could have catalyzed monomers in hydrothermal ocean vents

9. 2. How were organic monomers assembled into complex polymers?
Transition metals can lend and take away electrons from molecules
A combination of transition metal elements (copper, nickel) and ligands (small organic molecules) could have catalyzed monomers in hydrothermal ocean vents

10. 3. How did self-replicating molecules needed for inheritance arise?
Reactive surfaces model

11. RNA World = Variation for Free!
DNA
VS.
RNA
1/1x106 errors

12. 4. First membranes?
“All spontaneous processes proceed in the direction that increases entropy of the universe” (entropy = a measure of the disorder in a system)”

13. 4. First membranes? ORDER FOR FREE!
Lipids in water…
Bilayers form spontaneously! Why?

14. The First Membranes… Order For Free!
Lipids in water…
Initial State
Final State
Lipids
Free molecules (High S)
Fluid membrane
(Intermediate S)
Water
Ice-like shells
(Low S)
Free molecules
(High S)
Spontaneous biological order at the expense of universal disorder!

15. Other examples of entropy-driven order – “self-assembly”
Self-folding of
small polypeptides

16. TED Talks – Lee Cronin “Making Matter Come Alive”
How does he propose to define life?

17. TED Talks – Lee Cronin “Making Matter Come Alive”
How is Lee Cronin’s lab attempting to “make matter come alive?”
What are some of the implications of his research?
How does he propose to define life?

18. The Earliest Life was Prokaryotic…How Did Eukaryotes Evolve?

19. The Origin of the Mitochondria and Chloroplasts:
Early 1900s – Konstantin Merezhkovsky
“Chlorophyll bodies…behave like independent organisms… They are symbionts, not organs”

20. The Origin of the Mitochondria and Chloroplasts:
Early 1960s – Lynn Margulis
The Origin of Mitosing Eukaryotic Cells
Convincingly developed the view that chloroplasts and mitochondria have prokaryotic origins
National Medal of Science, 1999

21. Theory of Endosymbiosis
Ancestral anaerobic eukaryote engulfed another formerly free-living organism; became so tightly ingrained with one another  no longer free-living  gave rise to today’s aerobic and photosynthetic eukaryotic cells

22. Margulis’ Data Size Ribosomes Membrane DNA Characteristic Eukaryote
Prokaryote
Mitochondria
Chloroplast
Size
Ribosomes
Membrane
DNA
Characteristic
Eukaryote
Prokaryote
Mitochondria
Chloroplast
Size
100 m
1m
Ribosomes
80S
70S
Membrane
Single
membrane
Single membrane
Double membrane
DNA
Joined with proteins in chromosomes
Naked, circular

23. Quick Side-Note
Another example of non-mendelian genetics!
No!

24. Mitochondria and Chloroplasts reproduce by binary fission!
Margulis’ Data
Both prokaryotes and mitochondria and chloroplasts reproduce by binary fission!;
Mitochondria and Chloroplasts reproduce by binary fission!

25. Total Independence? Mitochondrial Genome
No! Mitochondria has lost important genes! Cannot be cultured independently! Where did these genes go They’ve been transferred to the nuclear genome!
Mitochondrial Genome

26. Is the loss of genes unusual? NO!
Ants and Mealybugs
Moranella bacteria inside a Tremblaya bacterium inside a Mealybug!

27. Is the loss of genes unusual? NO!

28. Other Endosymbionts? Cilia and Flagella were once spirochete bacteria?
Viral origin of the nucleus?
No!