Origins of Life Hypothesis
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- Pseudo Panspermia
- One could ask, where did life come from? Although it is not definite, the Pseudo-Panspermia hypothesis can be a promising answer
- However, they were hypothesized to have come from other planets which may have had unicellular organisms (prokaryotes) on them,after scientists had found amino acids inside of meteors
- About 4 billion years ago, Earth was a firey hellscape that had uninhabitable conditions. However, this was the time of the bombardment, where terrestrial planets were being frequently hit by meteorites.
- The meteorites formed craters on impact , and the unicellular oganisms sat there, slowly evolving and diversifying.
- Pseudo Panspermia
- The bombardment iself lasted around 20-20 million years, and after it's end, allowed the prokaryotes to really thrive.
- This hypothesis is known to be relioable since we know that tardigrades exist. Tardigrades are extremely durable organisms that can survive extreme conditions like space, and conditions of other planets, proving that they could have been carried by asteroids
- With conditions settled, one prokaryote in bacteria stood out, cyanobacteria.
- Cyanobacteria was capable of photosynthesis, and it produced oxygen as a product. Theyintroduction of oxygen allowed the ozone layer to be formed, in turn shielding Earth from harmfuil UV radiation.
- Endosymbiosis is a hypothesis that suggests that phagocytic prokaryotes (predator) absorbed smaller prokaryotes through endocytosis. However, whether it be a matter of the phagocytic cell not being able to digest the prey or the prey having defenses, the prey stayed inside the predator prokaryote. The 2 resulted in a symbiotic relationship, where the prey produced energy and the predator provided protection. As the host cell reproduced and evolved, the prey cells evolved too to become organelles, either chloroplasts, or mitochondria, depending on if it was an aerobic bacteria or a cyanobacteria.
- Prokaryote toEukaryote
- However, the evolution from unicellurlar to multicellular is a whole different process.
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