L6- The origin of life and microbial evolution Flashcards
What 2 important things for life were absent in the 1st 1/2 billion years?
Molecular O2 Liquid H20 (was too hot)
What do sedimentary rocks tell us?
They form in water so you can tell when water is present on Earth
When was the Earth formed?
4600 million years ago
When were sedimentary rocks formed?
3,860 million years ago
What did Miller show in 1950s?
Biological molecules could be formed abiotically (purely chemically) using UV radiation, lightning or meteor strikes as an energy source. From sugars, amino acids etc.
What are proteinoids and how could they be formed?
Protein-like molecules made abiotocally. Organic molecules splashed onto hot dry surfaces catalyses condensation and polymer formation
What can RNA do by itself?
Can self-replicate but inefficiently (makes errors). So it may have preceded cellular life.
What are the rough steps leading to cellularisation of life?
- Self replicating RNA enclosed in a lipoprotein vesicle
- RNA self replicated, mutated, evolved
- Evolution- switch from RNA to protein (enzymes)
- Gradual change- some protein-RNA complex enzymes
What are the advantages of changing from RNA to DNA?
Not as many mistakes in replication
All genetic info. in one place, only transcribe what’s needed- more efficient. Hence, greater fitness
In primitive cells, what was the reaction which made protons available so ATP could be made?
FeS + H2S—> FeS2 + H2
What are thermophillic microbes called?
Archaebacteria- now called Archae. (ancient bacteria)
Where were Archae found?
Hot water springs in early 70s e.g. yellowstone
Why was it so interesting to find Archae?
They were thriving in their conditions
Where are Archae’s ecosystems not dependent on light?
Volcanoes at tectonic plates. That’s where energy comes from.
What do organisms use as an energy source there?
FeS, H2S
