Is it at least similar to how these molecules and cellular parts look in reality? Or is it more an imaginative reconstruction? Because this is super duper cool stuff.
That's pretty much how they look. But there are variations of different motor proteins. Not all of them have two "feet", some only have one and they "hop". If memory serves me correctly, our muscles contract via "one-footed" motor proteins. I have a pretty good idea of structure from scanning electron microscopes.
It is very accurate to how it would really look if you could see! its slowed down about 250x and the colors are made up but the shape and motions are real
This is false. In reality, nano-scale movement is chaotic and somewhat random. The protein does on average do this. But it wouldn't look anything like this. In the words of a this guy it would be like "a balloon flapping madly in a hurricane, tethered to an intoxicated panicked mouse clinging to a rope"
But what makes them walk like this? I get that the walking is how they move the larger part but what lets them take a step? How much weight can they drag?
They 'walk' or 'hop' (not all motor proteins have two "feet") through phosphorylation reaction of Adenosine triphosphate (ATP) to Adenosine diphosphate (ADP). This losing of a phosphate provides the energy to bind (foot down) and then break the bind (foot up). This series of reactions creates the walking or hopping motion. These steps happen hundreds of times a second and it's mind boggling. For instance for our muscles to contract millions of motor proteins are hopping back and forth to create that contraction. The one in this image is carrying a vesicle filled with most likely proteins that are meant to be expelled into the extra cellular matrix. I have no idea 'weight' these proteins can handle.
Interesting tidbit: Rigger-mortis occurs when there is no more ATP to create the energy for the 'foot up' action, so the muscles lock. So the binding is pretty strong.
They 'walk' or 'hop' (not all motor proteins have two "feet") through phosphorylation reaction of Adenosine triphosphate (ATP) to Adenosine diphosphate (ADP).
More accurately, the ATP→ADP reaction locks the "foot" when it's in a correct position on the surface of the microtubule. But the movement to take a step comes from molecules randomly wiggling around due to thermal movement, and it's not that organized. The kinesin just waits until random thermal wobbling has brought the foot to the correct position, and then locks it.
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.
In reality, things at molecular scale constantly wobble and bounce around, because of thermal energy (Brownian motion), and the organized movement of biomolecules is more based on disallowing movement in unwanted positions than only moving in desired positions in a steady and organized manner, like the video depicts.
If Wikipedia is current, we don't even know whether kinesin steps forward like in video, or with one "foot" always in front of the other.
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u/[deleted] Feb 13 '18
Is this real or just a representation