How did life orginate? what process?
Chemical evolution?
How did the chemical evolution come about?
- This process may have occurred on Earth’s surface using chemicals formed by energetic processes within the atmosphere.
- Alternatively, it may have formed from chemicals synthesized in space and imported in IDPs
- or from chemicals synthesized in hydrothermal vents at mid-ocean ridges.
What three aspects of life must have all happened at the same time?
‘Three different aspects of life must all have emerged at approximately the same time:
>information storage and transfer
>metabolism
>vesicles (separating the organism from its environment). No single theory can explain all of this at the moment.
What is RNA world?
Life may have passed through a stage known as the RNA World. During this time, RNA performed the functions of information storage and catalysis that are now carried out by DNA and proteins.
When did life origin?
3.4 billion years ago
How do we know so much about early evolution?
Much of what we know about the early evolution of life comes from analyzing rRNA, or the DNA equivalent thereof.
What are methanogens?
Ancient organisms that produced methane, not the first!
What is a weak but common ancestor of all extant organisms?
Forskare tror att den första gemensamma förfadern till allt liv kan ha levt i väldigt varma miljöer. Det kan bero på att:
livet började i värme, eller
en stor asteroid dödade alla organismer som inte tålde
extrem värme.
Weaker evidence indicates that the common ancestor of all extant organisms lived in a hot environment. This could be explained by either a high-temperature origin of life or extinction of nonhyperthermophilic organisms by a giant impact. The latter hypothesis is consistent with life having originated during the heavy bombardment period prior to 3.8 billion years ago.
