1. Origin of first cell Flashcards
What is a protobiont?
Praorganism made by organic molecules. It is the first life form in the world.
Do we know shapes of protobionts? What organells did they have?
We don’t know the specific shape of protobionts, but we know that they had citoplasm, cell membrane and DNA.
How can we prove that protobionts were the first organisms?
There weren’t enough protobionts to have fossils of them today, but it can be proven with laboratory experiments.
Describe the shape of protobionts (from which to which shape they developed). What happened during this process?
They went from a mix of organic molecules in water (which can combine together) to a normal round shape. In that process, lipids were passively combining. That process is called abiogenesis. There were a lot of hits and misses, something was missing inside the protobiont (e.g. DNA).
What are lipids? What is the cell membrane mostly composed of?
Lipids are a type of biomolecules. Cell membrane are 90% lipids.
What is abiogenesis?
Abiogenesis is a process where protobionts originated from passive combine of molecules.
When did the first protobionts appear?
3.7 billion years ago. If it is proven for cyanobacteria to be older, then the first protobionts originated 4.4 billion years ago.
Where did abiogenesis occur?
Abiogenesis occured in hydrothermal vents which are located in big depths. Hydrothermal vents are chimneys which eject smoke and high temperatures (higher than 100°C). A very big amount of archea and other organisms can be found in the area of hydrothermal vents.
What are stromatolites?
Stromatolites are specific rocks which contain fossilized cyanobacteria. They are the oldest undisputed fossils and the strongest evidence of life.
Which organisms developed the process of photosynthesis?
Cyanobacteria. It was a rapid reproduction because there was enough sunlight and CO2 (most composition of the atmosphere).
How were stromatolites formed?
The brownish sea became slimy green (because of all the cyanobacteria) and after that they died because they produced too much oxygen and fell on the bottom. Layers of cyanobacteria were created which resulted with stromatolites. The biggest amount of stromatolites is found in Australia.
When did first stromatolites form?
3.5 billion years ago. If it is proven for cyanobacteria to be older, then 4.2 billion years old.
