How did chemisty and oceans produce this?

Remember the two keys to evolution of planetary atmospheres:

• Fate of the water vapor (gaseous, liquid, solid)
• Fate of the Carbon Dioxide (stays in atmosphere vs. dissolves in liquid water)

After condensation of water vapor produced the earth's oceans, thus sweeping out the carbon dioxide and locking it up into rocks, our atmosphere was mostly nitrogen.

So now let's make some life over the next billion years or so:

Amino Acids now loosely mixed in the oceans

• 2D view of glycine
• 3D view of glycine

• Most amino acids have a mirror image (L and D)
  • L and D both found in meteorites
  • L only in organisms on the earth
  • why is D selected against?

So now we have some amino acids (monomers) loosely mixed in the oceans. Liquid medium is important:

• Protects molecules from UV photon disruption
• Ease of transport and Interaction

Next goal is to combine monomers into Polymers (peptide chains)

Example formation of a peptide chain

How did chemisty and oceans produce this?

• concentration of monomers and enzymes and proteins which act as an energy source
• O and OH are removed (hydration)
• monomers join together to make polymers

4 Billion years ago:

• NO cells
• need to concentrate monomers together to facilitate polymer formatoin

Step 2: Concentrate the Monomers:

• Local Evaporation (clays) Tides ?
• heat from expelled lava (St. Helens)
• tidal pools (bigger tides)
• freezing of water

Energy Sources:

• lightning (Jupiter)
• heat
• UV

All of the above are quite inefficient compared to enzymes

Clays Silicate Surfaces acts as a catalyst

Peptide chains of around 100 amino acids can be found today

Does the reaction on the silicate surfaces favor L amino acids?

Step 3: BIG, Unknown Next Step need to organize a system capable of self-replication (e.g. DNA)

• Organic polymers in high concentration seperate out from liquid medium as individual droplets proto-cells
• long chain molecules can act as a membrane

EVOLTUIONARY ADVANTAGE: Polymers that could reproduce themselves will survive

• Trial and Error until "right" combination is acheived (DNA)
• every living organism on the earth has DNA
• Fossil Record indicates that single celled life first emerged 3.5 billion years ago
• Therefore it took one billion years to go from atmospheric chemistry to blue green algaes via the oceanic pathway
• All you need is time?

Now we have a multiplying population of bacteria (prokaryotes) that has to eat to survive:

What to eat?

• First feed off other organic molecules via fermentation
• fermentation is very inefficient, releases little energy
• Big problem the food supply is running out

EVOLTUIONARY ADVANTAGE: Bacteria that could process plentiful UV light and INorganic molecules will survive

• are most plentiful molecules dissolved in the oceans
• requires least amount of energy to break apart
• early blue green algae therefore metabolized giving off sulfur as a waste product stinky anerobic photosynthesis
• Important photosynthesis evolved from a need for the bacteria to be able to feed themselves and multiply