1. Origin of first cell

3. WHEN Did Life Evolve? Earth was molten during Hadean
Then cooled somewhat by 3.9 billion years ago
Solid rock & water could remain liquid at the surface

4. Origin of the Oceans water vapor condenses and falls as rain
oceans accumulated
salts added over 3.9 billion years as material eroded from continents

5. oxygen breaks down organic molecules
life must have evolved before oxygen abundant
Early Archean sediment dark-colored = unoxidized
oxidized (rusted) sediment appears about 3.5 billion years ago
life must have evolved before 3.5 bya

6. WHEN Did Life Evolve? oldest (possible) life-forms
~3.5 billion years old
life likely evolved between 3.9 and 3.5 billion years ago

7. How Did Life Evolve ?

8. Monomers building blocks of life must form for life to evolve
how did monomers first form?
Amino Acids

9. Monomer Synthesis Miller and Urey - created “Early Earth Apparatus”
early Earth atmosphere in the top
electrodes to produce “lightning”
primordial pond in the bottom

10. Results: after a week, primordial pond became primordial soup
12 of 20 most common amino acids synthesized + other stuff
next step: polymerization

11. Polymers chains of molecules proteins carbohydrates lipids
nucleic acids

12. Requirements for Polymerization
energy source: to drive reactions
protection: from too much energy
concentration: to bring materials together so they can react together
catalysts: to make reactions happen faster and more efficiently

13. Energy Source Energy induces chemical reactions volcanoes lightening
cosmic rays
UV radiation

14. Protection too much energy can be a bad thing!
early organic material protected by: rock ledges, under ice, under thin film of sediment, just under surface of water

15. Concentration
when chemicals are dispersed in water, reactions are less likely to happen
concentration brings reactants together
evaporation
freezing
scums
droplets, bubbles
clay

16. Concentration - clay clay forms from sedimentary
particles called platelets
platelets are:
very small
flat
with negative charge on surface

17. Clay organic molecules are attracted to clay surface
concentrate and align
Examples: bentonite (kitty litter, mud masks), kaolinite (Kaopectate)

18. Catalysts decrease amount of energy needed for chemical reactions
so increase the rate of chemical reactions
catalysts in the body = enzymes
Inorganic catalysts often metal ions

19. Making Cells what is required to make a cell?
DNA: passes on genetic code
cell membrane:
made of phospholipids

20. Phospholipids
each molecule has a hydrophobic end and a hydrophilic end
when surrounded by water, fatty acids form shapes where the hydrophobic ends protected on the inside

21. Protobionts Phospholipid spheres that form naturally
polymers and enzymes concentrated inside
reactions occur inside
protobionts:
maintain their structure
increase in size over time
divide when too large
selectively absorb and release compounds
metabolize starch
store and release energy

22. Are Protobionts Alive? No
they can’t replicate themselves

23. Replication
process by which organisms make genetic copies of themselves
asexual reproduction
sexual reproduction

24. Origin of Heredity
short strands (50 nucleotides) of RNA assemble naturally
replicate themselves if more monomers available
zinc, copper act as catalysts