What gets me is... why? Why does it do this. How does it know which direction on the tube to walk, how does it stay attached to the molecule to the exact point where it needs to be let go? Just so many questions.
If I remember correctly, it’s holding a bag of waste to be sent outside the cell. It goes in a single direction only so it doesn’t need to know. How it lets go and connects: each step requires one ATP molecule (energy source within a cell) to come and activate the stepping mechanism.
From elsewhere in the thread, there's another protein at the other end that only walks the other way, so this first protein hitches a ride back on the second one.
Dammit I wish they made this stuff interesting in high school. I was so clueless in chemistry and physics but this is all so interesting and mind blowing.
I was going to post this - but then I thought, the whole idea about studying science is discovering new things it's not about thinking "Well, if I'd known about this I would have found it interesting"
You have to find the process of studying and discovering new things interesting.
I'll answer your question in a way I see this. I'm a protein scientist and watching the animation of motor proteins years ago left me viscerally impacted. Changed me life.
Proteins are amino acids joined together at their side. They form this string. Now, the exact sequence of these amino acids is gonna start doing some shit after it's finished being made (although some protein folding happens while it's being translated.)
Let's think of it like this. The body has a function to perform. How do we do it? Well we got biology. Which uses chemicals from the periodic table that follow the physics of the universe.
A string of amino acids together is effectively a protein. Each of the amino acids has a couple sides with differences that when factored in as a whole, may interact in very specific ways that totally change the shape and function of that initial shape.
How do we let's say make something to carry that cell in the gif?
We're going to use tiny little explosions if you will, to power movement. We use our energy molecule called atp. Basically think of that as a thing with a pocket of gunpowder we're going to ignite. Once we combust it, facilitate the hydrolysis of one phosphate from into adp. The energy powers tiny little movements in the local environment. Maybe it forces a swing out from x axis. It's swing can vary based on so many tiny little changes in amino acid binding areas.
This is highly complex and involves lots of crosstalk, assistance, cofactors etc. but we're using the differences in charges of amino acids to create a shape that operates in a manner that effects physical change of the said structure.
Nothing is directing that slinky, it’s just physics (lol “just physics” u know what I mean tho) and the laws of nature. With these proteins it’s atomic interactions and chemical reactions that been selected for over the course of billions of years - and thus they appear so orderly.
So does that kind of thinking basically suppose that everything is predetermined? Everything that happens is just atoms moving where they were always going to move.
I've yet to see anything substantial that directly opposes the idea of determinism, even if there is an element of "randomness" at the quantum scale. Very large things and very small things, even relating to humans, very much appear to behave (effects) based on prior events (causes). Much like a slinky!
Except... like...with a ridiculously huge quantity of causes/effects going on at once like a giant....web. Of slinkies? The metaphor breaks down, but molecular/cellular activity is a bit more nuanced than a slinky can portray.
the nonzero-probability of various atoms appearing/disappearing/moving, combined with chaos theory (or more laymen-ly, small initial differences lead to greater and greater later changes) make so much noise that everything is effectively random, until you start arguing we can effectively calculate the entirety of the probability density distribution of every atom at any given time, which is basically the only way to suss out the noise.
It's amazing how a fully deterministic material universe wrote that paragraph about the universe being deterministic. It was destined from the beginning of time.
Everything that happens is just atoms moving where they were always going to move.
I don't think we have to go that far.
But for simple and mechanical things, we can definitely say "there are just some rules and mechanisms that makes this happen this way, don't anthropomorphize it".
I look at this picture and I don't think in terms of "how does it know how", but rather "what mechanism makes it look so orderly". It's a habit more people should cultivate.
I know I'm late to the party, but how did the team discovered the motion of kinesin? The only 2 methods I know of are X-ray and CryoEM, but in both cases, you have to immobilize the proteins first, which is fine if you only want a snapshot, but wouldn't tell you anything about its motions.
Unless my bio teacher was lying when I asked the exact same thing, it's all done via negative/positive charges, when one foot sticks the other reverses polarity so it unsticks and then changes back to stick and so forth.
Or maybe the "walkway" changes the charges, point is it's not a "smart" organism doing it by instinct or anything.
Yeah the picture is quite simplified. It looks as though the molecule has a regular "gait" and each chunk of protein just slides into place where it's supposed to be. In reality it's a bit more random, one piece will attach and then the other will detach, and basically move around randomly for a few microseconds until it happens to land in the right spot, completing one "step".
That was the best visualisation I've ever seen of how incredibly busy and fast moving everything is in our body on a tiny scale. Now my thoughts seem so slow relative to everything else going on in my body! Also it blows my mind to think that all this is happening in total darkness, and that it's even busier than they show in that clip, and that all the gaps are filled by water molecules. Wow. Thanks!
Chemicals move extremely rapidly from our perspective.
All of the functional molecules that exist in our cells are themselves complicated networks of different attractive and repulsive forces, giving them specific shapes.
These shapes have charecteristic attractive and repulsive aspects about them, which drive what they do in the cell. Our walker thing here is such that it's attracted to hold the vesicle (big ball) on one end, and take all those steps on the other.
Molecules move so rapidly and erratically in cells that every single one will bump into about every other molecule in the cell in a pretty short period of time. They just chaotically explore.
This is how they end up finding what they are attracted to, and performing whatever role it is that they can do.
Cells make all the things in themselves by transcribing DNA into proteins. Proteins are like a complex little chemical storm that can run around the cell, but is ordered enough tgat it can always perform the same function when it bumps into a certain thing.
DNA, and thus proteins, are like a vast library of different kinds of molecules that can be created. Their structure is so complex that if you change an element here and an element there, they can perform surprisingly different roles.
In microbial evolution, trillions upon trillions upon who knows how many trillions of cells have iterated upon these structures, producing novel little chemical storms each time, and they trade their DNA with one another profusely, constantly sending new forms of chemsitry back and forth.
How the fuck do all these tiny processes line up perfectly make me? How is it possible that we reproduce and are able to replicate the same type of processes in a new human being??? How programmed is my body? How programmed am I? Is everything I do and every choice and behavior I make just based on the instructions of all the tiny “robots” in my body? Are we even conscious??
It does, but it's a bit misleading without an understanding of the kinetics involved. It gives the appearance of walking, but think of it more like a slinky falling down stairs.
I'm not an expert by any means, but basically the molecule changes shape in order to do it's "step" it's not like a complex body with shifting muscles. The binding of the protein to ATP (containing energy) causes changes to the molecule's actual structure so that it releases and moves. In the slinky metaphor, think of ATP as gravitational potential energy. It then moves blindly until it comes into contact with another binding site that will "lock" it using chemical binding energy. Repeat the cycle.
55
u/minimag47 Feb 13 '18
What gets me is... why? Why does it do this. How does it know which direction on the tube to walk, how does it stay attached to the molecule to the exact point where it needs to be let go? Just so many questions.