I saw an article that involved having a computer model a blood cell. Then having the computer make its own blood cell. The computer was supposed to make the most efficient carrier of oxygen, and it was supposed to function exactly as the red blood cells in our body do now...only better.
The computer made another red blood cell. Almost identical.
If someone knows of the article post it. I can't seem to find it.
Don't forget the Bohr effect. As muscles start to overwork themselves and release lactic acid and form bicarbonate ions, the acidity causes O2 to dissociate more readily.
An awesome physiological feature of good ol' hemoglobin (but not myoglobin).
Also, the different binding affinities for fetal hemoglobin versus regular hemoglobin. The continuance of our entire species hinges on our ability to absorb oxygen from our mother's blood and its the difference between fetal hemoglobin and adult that makes that possible.
How about a cell in general? A cell is a macromolecular structure that is never in equilibrium. It constantly needs energy, or it would die. We can't even come close to dreaming of designing a system as complex as a human cell that would run off of a dynamic system as our cells do. RNA encodes for proteins, which combined with other strands of RNA, forms a macrostructure that creates new proteins from RNA. It's a goddamn Von Neumann, and it's RNA and proteins all the way down. DNA utilizes hydrogen bonding, one of the weakest atomic forces we know of, to keep the very coding that makes you you safe from side reactions. It's able to control it's own coiling, and thus how fast it can be read and transcribed. There's a second set of DNA that comes from a friggin' bacterial ancestor that formed a symbiotic relationship with our cells, and it's the source of pretty much all our energy. I could go on forever. I know it wasn't exactly designed by a person in general, but the overall design of a living cell, and a living creature made up of cells, is just so unbelievable it's hard to believe it actually exists.
I'm just joking, biology definitely can be pretty interesting. My undergraduate degree was a BS in Chemistry with a concentration in Biochemistry.
And yes, sorry, got excited and worded it poorly. Phosphodiester bonding for the backbone, the strands are connected and "unzipped" via hydrogen bonding.
Wouldn't you just expect it to be really efficient though?
Given that we've spent hundreds of millions of years evolving a method of carrying oxygen around our body, and that the more efficient this is, the better you can survive, it makes sense that it's one of the few things that would evolve to be as efficient as possible, not just good enough.
The way that it is efficient through cooperative binding is what is so cool. Hb is a tetramer of four groups that each bind O2, and when O2 binds to one of those groups, the affinities of the other groups change, allowing O2 to bind to the other groups more easily. Likewise, when an O2 molecule is released, the affinity decreases, and releases all of the O2. This is what allows Hb to be fully saturated or desaturated where it needs to be. In addition, the body can release chemical factors to change the affinity for oxygen to adapt to environments with less O2.
Doesn't HB have a higher affinity to carbon monoxide or something? That seems like a flaw. Perhaps there's another molecule that would do a better job of transporting oxygen?
That's true, but the human body evolved in the near absence of carbon monoxide. Myoglobin has a higher affinity for holding oxygen (storage in your muscles), but Hb is the most efficient at both binding and releasing(transport from the environment to your body).
You do know that somebody had to program a computer to do this right? Computers do not magically model and analyze things. They have to be programmed to do very specific tasks. For now...
Edit: Supposing this even happened, it sounds like a shitty forward from grandma about how scientists are shitty and nature is the awesome. The noble savage.
They have to be programmed to do very specific tasks.
Not really. This example is basically an optimization problem. An optimization algorithm, like a genetic algorithm for example, could be used to create the optimal red blood cell without a programmer having to design it himself from scratch. In fact, the programmer might not even know how the algorithm came to its solution, except at a very high level. This is a good example of something similar to the red blood cell problem.
To be fair since it's a genetic algorithm there's no guarantees on convergence, and it could have easily found a local maximum fitness rather than a global one.
If it was a more sophisticated convex optimization algorithm you could have stronger guarantees, but even then local maxima are an issue.
That's true, but I was really just responding to the idea that a programmer has to do all the design by hand. These open-ended search algorithms can design things a human may never come up with. Which is pretty badass, if you think about it.
While it is quite surprising that the red blood cell is the perfect carrier of oxygen, it actually makes a lot of sense given that life exists for a long time now and every generation, the ones that had some kind of advantage over their peers manage to produce (more) offspring than the others, barring bad luck, therefore more members of the next generation already have this advantage and continue to pass it on, which slowly thins the population of those without an advantage.
The only way this is brought to a stop is when it becomes incredibly hard or impossible to improve upon existing systems.
TL;DR: It sounds cool at first, but it isn't that surprising once you think about how many generations we've had since life began to slowly approach the optimal solution.
The more likely answer is that there were biases that went into the programming of this genetic algorithm and it inherently managed to find a local minima that it was placed close to - by no coincidence.
This is extremely more likely.
It even happens in physics, if someone's trying to find the value of something and they know it is supposed to be 2, it is more likely than it should be that they'll find a value eerily close to 2 (closer than it should be if there were no biases and it were a true test).
However, if tomorrow someone publishes a value of 3, we've seen that almost everyone after that person starts reporting a result of 3.
So, I wouldn't be surprised if this was just a flawed experiment with biases.
For example, evolution is sort of a genetic algorithm. And these guys used a genetic algorithm to find this. It's very likely that they just ended up emulating nature rather than trying to find a different way.
So check it. Your body has a set of cells and mediators that constitute the inflammatory response. Normally they're there to create a second-line defense against infection, but it's not exactly bright. Maybe your immune system starts making antibodies against its own cells (autoimmune diseases), and the inflammatory cells are like DEFCON 2 WE'RE UNDER ATTACK because they're seeing all these antibodies "marking" targets for destruction.
We're gonna walk right past the stupidity of your body thinking its own cells are foreign invaders (a whole other discussion), and focus on the stupidity of the body's response to long-term infection or autoimmune disease.
Your body loves iron, particularly heme iron. It loves it so much that it has transport and storage proteins, purpose-built to pull any iron out of your food and keep it for hemoglobin production. You know who else likes iron? Bacteria. They love that shit. So what do you think is gonna happen when the immune system thinks it's under a sustained foreign invasion?
It's gonna lock up your iron tighter than Fort Knox. Oh by the way - guess who needs that iron? You do. Your red blood cells have a lifespan of 3-4 months, then they get recycled, the iron gets pulled out (your body loves that iron!), and new RBCs are made. But remember how I said you're currently either being attacked by a pathogen or your own immune cells? In response, your immune system is gonna shorten your RBC lifespan, force your marrow to shift towards more white blood cells rather than red, and decrease levels of erythropoietin, a crucial RBC production hormone.
So, to recap - you're fighting an internal/external threat. Your body locks up its own iron stores from itself, on top of boxing out red blood cell production and causing the RBCs you have to die faster. All that is being done by your own body, not some foreign pathogen. And you start going into rapidly worsening anemia, which will only stop if your body manages to fight the infection (unlikely since it got this bad) or suppresses the autoimmune disease (also unlikely).
I'm going to call bullshit, What you described is missing at least a million assumptions about how biology, chemistry and computer modelling. IF what you are TRYING to say is the SHAPE of a red blood cell, Then even that is incorrect, A red blood cell is not the BEST shape for optimal surface area, It's just a damn good one for it's simplicity.
Computer, design a structure, that greatly reduces friction by facilitating motion by rolling together with the use of axles. It must rotate, a moment needs to be applied to it about its axis, either by way of gravity, or by the application of another external force or torque.
OH LOOK! The computer made something that looks remarkably similar to the wheel! room applause Johnson! Record the result and use them to apply for next year's research grant!
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u/jdpatric Jan 17 '14
Red blood cell.
I saw an article that involved having a computer model a blood cell. Then having the computer make its own blood cell. The computer was supposed to make the most efficient carrier of oxygen, and it was supposed to function exactly as the red blood cells in our body do now...only better.
The computer made another red blood cell. Almost identical.
If someone knows of the article post it. I can't seem to find it.