Dette betyder at transkription og translation er adskilt i tid og rum. Promotere er DNA-sekvenser, der signalerer at transskription kan starte her. Det det kan bl. En vigtig gruppe af aktivatorer er kernereceptorer , som kan binde hormoner og derefter aktivere transkription.
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Her siges det, at faget er en blanding af Biologi B og Kemi B. But keemi is the current understanding of when things happened. But what happens is we enter into the Proterozoic Eon. I mean the current theory is that mitochondria is actually descended from kind of an ancient prokaryotic cell, an ancient bacteria. Video udskrift We kmi off in the last video in the Archean Eon. But give or take a few hundred millions of years, one prokaryote got engulfed by another prokaryote, and said, hey, we do pretty well living together.
And we think this started to happen about 2. I can only imagine that 50 years from now, or years from now, if someone is still watching this video, a lot of this might say, hey, we found out later that oxygen started to accumulate in the atmosphere earlier or later or that eukaryotes occurred earlier or later.
It actually has its own DNA. Eukaryotic organisms, remember, these are organisms that have nuclear membranes around their DNA. It just would not be able to live. We needed this to happen. Some of that oxygen goes into the upper atmosphere. The estimates are 50 to trillion eukaryotic cells.
So this kind of sets the stage for in the next eon, for animals or living levendess, to eventually get on to the land. The land was just open to it. So we are able to find rocks that we can date to be roughly 3.
And, of course, this boundary is vague. And we said in the last video that they were producing oxygen, but most of that oxygen was being absorbed by iron in the oceans.
You can go to the biology playlist. Now, the other really interesting thing that drt in the Archean Eon, and it really has pretty profound effects once we get into the Proterozoic Eon, is that you lrvendes to have cyanobacteria produce oxygen. Anything on the land would have just gotten irradiated. So this right over here, 2. So what happened, and what I guess has to happen, and the reason why we are able to live on land now is that we have an ozone layer.
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DET LEVENDES KEMI PDF