So, here's what I claim. I claim that every time two of those come together, there's a chance for a water molecule to leave and produce what is called an ester bond. acid vesicle under conditions where an activated monomer can get across the membrane, add itself to that partial DNA to complete the double-helix.
There must be a mechanism. And if you just do nothing more than dry down your lipid, mix in your solution, and shake it up, what you discover is that you have self-assembled lipid vesicles . That's that cloudiness you see there. And the lipid vesicles have encapsulated the RNA. It's as simple as that to make what we call protocells. These are steps toward the origin of life--biggish molecules with potential catalytic replicating ability trapped inside
It's as simple as that to make what we call protocells. These are steps toward the origin of life--biggish molecules with potential catalytic replicating ability trapped inside lipid vesicles . So, that's how simple it is. So we're not saying anything outlandish when I claim that it's easy to do and easy to conceive of. Now we're actually trying to see whether that does any good with respect to the origin of a replicating catalytic system. Well, I wanted to take you one more step in the history of
now it's inside the vesicles . Some of the vesicles have stuff inside. To prove that to you, there's an image of what we call freeze-fracture electromicroscopy. There's some vesicles on the left and you can see they're about the size of bacteria--about two microns. When you dry them they turn into that dry multilamellar lipid phase. And that is what we believe is able to trap. Anything that's outside gets trapped between those lipid lamellasr you see on the right.
So, here's what I claim. I claim that every time two of those come together, there's a chance for a water molecule to leave and produce what is called an ester bond. We have phospholipid vesicles . That's the stuff that's gonna form that multilamellar matrix. Gonna dry it down under carbon dioxide. Oxygen tends to inhibit this. Gonna give it
So we think there are active mechanisms of DNA repair going on here that is very interesting to study and understand. And these organisms also have some internal vesicles that may or may not play a role on radiation resistance. We don't know if this is viral particles that could have DNA repair enzymes like polymerases.
So, that's what a membrane looks like, the lipid component. So keep that in mind because you're gonna see that again as we go on. Last point to make before I get to the molecular biology is that a property of vesicles is that when they fuse, they turn into a multilamellar matrix--what we call a lipid matrix array.
And anything that is outside becomes trapped between those layers. And you can see them trapped, the little pink lines there. When you rehydrate, you get the stuff back and now it's inside the vesicles . Some of the vesicles have stuff inside. To prove that to you, there's an image of what we call freeze-fracture electromicroscopy. There's some vesicles on the left and you can see they're about the size of bacteria--about two microns. When you dry them they turn into that dry multilamellar lipid phase. And that
If you look closely, you can see that-- well, it's a little hard to see, but there is some structure in the cell that's not moving. The only thing that's moving is this vesicle , and it's because it's been grabbed by one of these optical tweezers and moved around. People can do this with single atoms all way up to nanotubes.
have been available on the early Earth for the first living cells to take advantage of as a house to live in, as they did the rest of what life is all about. So here's a phase image of some of the vesicles . We captured some fluorescent dye in it. That's what you see over on the right-hand side there, just to demonstrate that these are actually compartments that can contain something.
So, here's what I claim. I claim that every time two of those come together, there's a chance for a water molecule to leave and produce what is called an ester bond. paper and in it we showed that if you dried outdown vesicles with monomers and cycle it
So, here's what I claim. I claim that every time two of those come together, there's a chance for a water molecule to leave and produce what is called an ester bond. And then, those large vesicles can divide into smaller vesicles . So, that's about where we are now in the search for how life began and how to simulate it in the laboratory.
We had very little time to equip the boat. This is actually one of the cells building the plate inside the-- inside some vesicle and extruding the plates.
by Rosalyn Bangham, that's Alec's wife. Now the conversation turned to a lecture that Alec had given a few years earlier at Bristol University with the title, ‘Membranes Came First.’ “Alec argued that the self-assembly properties of lipids were such that the membrane's vesicles must have been present on the early Earth, long before nucleic acids and proteins came along. But then we were stumped. What was the prebiotic equivalent of lipids that can self-assemble into membranes and where did they come from?"
is what we believe is able to trap. Anything that's outside gets trapped between those lipid lamellasr you see on the right. To prove that to you, we put some DNA in with some vesicles , put it through a single dry-down ied-out, rehydration. All those bright fluorescent is stained DNA inside the vesicles . It was all outside to begin with. So this just demonstrates how powerful it is.
So check this out. Here are five images of, in this particular case, it's called a vesicle . It's a substructure withinside an algae cell.
me into research on the origin of life. “ A few years earlier, Alec had discovered the self-assembly properties of phospholipid and showed that lecithin extracted from egg yolks could produce microscopic vesicles , ultimately forming structures that we now call liposomes.
a microscope and let the chloroform dry. And then you add water, which is the way you watch self-assembly, and this is what I saw. Really quite extraordinary. This stuff has never been alive, never part of a life process, but it still could self-assemble into membranous vesicles . And we propose that these are the kinds of compartments that would have been available on the early Earth for the first living cells to take advantage of as a house to live in, as they did the rest of what life is all about.
acid as well--DNA. So, I'm gonna put a few milligrams in here. It dissolves right away. This is water soluble. And the question is how could something like this, even if it got synthesized by some process on the early Earth, how could it get into these vesicles I showed you, because vesicles are relatively impermeable to make molecules?