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This IBDP Biology Blog post will look at the origins of different types of molecules, as well as the endosymbiotic theory.
Origin of Organic Molecules
Miller Urey Experiment 1953 and 1958
- In 1953 they created an experiment where they simulated the conditions they believed to be on Early Earth- hydrogen, ammonia and methane with electrodes to simulate lightning (a primordial soup)
- 5 organic molecules were formed
- However heavily criticised as the gases used didn’t represent all the gases found in the atmosphere and methionine wasn’t found which is the starter amino acid to all protein
Molecular Panspermia- suggested organic molecules originated in space
- Spectral analysis showed glycine is present in nebulas, similarly meteorites and comets contain amino acids.
- 4 billion years ago earth was showered with comets- the impact could have polymerised certain amino acids into polypeptides
- Sydney Fox- showed amino acids could polymerise and form proteinoid spheres
Endosymbiotic Theory
- A prokaryote cell absorbed another smaller cell but instead of being digested the cells live symbiotically
- Believe a photosynthetic cell was absorbed therefore mitochondria were created
These engulfed cells are thought to:
- Have double membranes
- Their own DNA
- Can perform independent protein synthesis using small ribosomes
- Can replicate themselves within the host
That is all for this post!
References:
- https://www.google.com/url?sa=i&url=http%3A%2F%2Fib.bioninja.com.au%2Fstandard-level%2Ftopic-1-cell-biology%2F15-the-origin-of-cells%2Fendosymbiosis.html&psig=AOvVaw0gqB9OEY0QI6bfXVEDUHcb&ust=1627282787072000&source=images&cd=vfe&ved=0CAsQjRxqFwoTCIj-8_bS_fECFQAAAAAdAAAAABAD
Drafted bby Venetia (Biology)