Our example tells us that scientists normally organize biological molecules into 4 groups, and those are nucleic acids, proteins, carbohydrates, and lipids. And you're likely familiar with those from earlier in the course. Alright. So our questions here, though, say based on our current understanding of how life may have begun, which type of macromolecule would seem least essential to the first life forms? Alright.
So what do you think? Of those, what was least essential? Well, in our lesson video, we talked about nucleic acids. We talked about RNA. We talked about proteins, how amino acids could form and polymerize, and we talked about lipids, about those lipid bilayers making those protocells.
We didn't talk about carbohydrates. So that's going to be my answer. Now to be clear, carbohydrates could have formed in those early chemical reactions, and certainly simple carbohydrates were found in the simple chemical reactions that were done in experiments to model the first amino acids being formed. So they were around.
They could have been used as sort of a food source for early life, but they weren't part of living things or made by living things, probably for a relatively long time in the history of life. Alright. B here says, according to the RNA world hypothesis, which 2 types of macromolecules would seem the most essential? Alright. So think about that.
Well, RNA world hypothesis, that clues me into one of them pretty quickly. Right? RNA. RNA is a nucleic acid. So that seems pretty essential for the RNA world hypothesis to have nucleic acids because RNA, well, that's a nucleic acid.
Alright. But remember that RNA world, we're talking about this RNA that can be self-replicating and work as a catalyst. And we said that it could be captured in these protocells or these vesicles. So what made up those protocells or vesicles? That's the lipids.
Right? So with lipids and nucleic acids, together, you can start to get that RNA world. Alright. Well, C here says, some scientists argue that life arose metabolism first, where self-sustaining chemical reactions housed in protocells developed first, before the development of genetic material. If this hypothesis is correct, which type of biological macromolecule would be most essential to the development of life?
Alright. So think about that for a second. Well, this seems to hinge on this idea of protocells. Right? And protocells, we said, are just basically vesicles, these lipid bilayers.
Well, I just said it. Right? Lipid bilayers, that's what makes those protocells. So some people think that you just started out with these lipid bilayers with these chemical reactions that themselves are almost self-replicating, and later on, you get things like RNA. Alright.
Now that just sort of highlights, we don't know how this happened, and we probably never will exactly for sure. But we do have hypotheses, and we can see how these things could have worked. Alright. Again, we'll look at this more and more practice after this. Please check it out.