Here is Wim's video: ua-cam.com/video/jFLUEBGTac8/v-deo.html Here is Hanks video: ua-cam.com/video/qV0udTvYK6M/v-deo.html Here are several other videos of various desmids dividing (some in the genus Micrasterias). Several of these were briefly shown in my video: ua-cam.com/video/0P7RQV51XvU/v-deo.html ua-cam.com/video/llO0ZZlSGc8/v-deo.html ua-cam.com/video/XwpFhh3Lqhs/v-deo.html ua-cam.com/video/BC1m26CtXY0/v-deo.html ua-cam.com/video/Uc9ppqqCMmI/v-deo.html ua-cam.com/video/gzh5j3NJ5-Q/v-deo.html
This reminds me of how bees don't design the shape of the cells in honeycombs, but rather the hexagonal shape is determined by the physical forces exerted on them.
My explanation: For given osmotic pressure, the external force is proportional to the area but the surface tension is only proportional to the length of the perimeter. Area scales quadratically, perimeter linearly, so to preserve the force equilibrium, there is dimple formation and twinning at the surfaces to increase the perimeter to match the increase in area. Dimple forms where the stress is maximum, so that's where twinning is most likely. Very similar things happen for crack propagation, as the crack propagates at the rayleigh velocity and can't go faster to dissipate crack energy, there is crack twinning, so we see a fractal nature of crack propagation. Its got more to do with physics at at this point. One more thing, I remember watching Robert Sapolsky's lectures where he said that "what the gene does" is meaningless statement, but what the "gene environment interaction is" is a meaningful statement. Evo-devo is just as much physics and mechanics as it is biology. The pop-sci "because evolution" reasoning to every question is just absurd speculation, one has to always demonstrate first what mechanism is taking place exactly before one can show how its favourable by natural selection. The shape of a micelle is not determined by evolution, its just the shape with the minimum potential energy.
My first guess would be symmetry is the most favorable means (given certain developmental constraints) of surface enlargement. An asymmetrical form would maybe result in slightly less photosynthesis and would thus be selected against
Are the same genes responsable for both halves of a symmetric organisms?If so, maybe symmetry is just a way to create complexity with the least amount of information.
Have you found any experimental work corroborating your hunch such as separating the two hemi cells before growth or changing the water pressure during growth ? Tension cues can also be revealed with various microscopy technique. Maybe the models invoking molecular cues were thought of because your hunch was already proved non conclusive. Thanks for the interesting biological question anyway!
I have not seen anyone explore the tension issue and I was surprised it had not been done. I'd actually love to work with someone on it. The trick with separating them would be doing so without ripping the cells. I think messing with them in a vacuum chamber could reveal it, though.
@@StatedCasually please do check the spam filter of your channel. I've answered twice to your message with links and it seems those comments are witheld from view
For some reason links seem disabled on this account, even though they are not disabled under the settings on my channel. I've had this issue on Stated Clearly too and tried to get UA-cam support to fix it but they never responded. Not only that, I can't see your message in the "held for review" tab. Looks like they were simply deleted by UA-cam for some reason. Try sending via twitter @statedclearly or my email and I'll post them. UA-cam lets me post links in the comments still.
I think there are multiple evolutionary and even reasons based on physics why microrganisms are spherical and symmetrical. Being spherical would require a lot less genes since it is a simple shape to grow and the material needed for cell wall growth would be equal at all sides. Locomotion may also benifit organisms that are symmetrical and symmetrical organisms better react to stimuli. And that is why the group bilateria was favored by natural selection. Thanks for the video. It is a really interesting topic.
Sir, In Gray anatomy, at cells chapter, Its written like this - Cell shape is determined by inner constitutes, similar cells interaction (Tissues) and external interaction. Along with that, Is it any specific genes for cell shape?
From what I understand your argument is essentially that the shape is a result of mainly physical forces. You mentioned that the model from the paper you discussed seemed too complicated as it assumed other interactions. My question, then, is what's stopping other cells developing the same shape? If this shape is entirely driven by the physics you outlined, what's stopping that from occurring in other cells from other species? Of course if I've missed anything please feel free to call me out on that 😅😅
DNA sequence controls what types of proteins can be made and the timing of protein production. These proteins control the speed of wall growth, the thickness, and so on (so ultimately, the genes are controlling this). Changes in those genes will cause changes in the cell's morphology, but they do this by changing how the cell interacts with the environment. The indentations themselves are caused by a simple physical collapse of the membrane under pressure, as it interacts with the environment.
I wonder if there has been an analysis of active / used genes in symmetrical vs asymmetrical organisms. My hypothesis is if there is an evolutionary advantage to symmetry it would be due to concision of gene expression.
That's a good question. Physically I can only guess how that's done. From a selective point of view, being flat has several possible advantages, one being that it increases the surface area to volume ratio which can be good for catching more sunlight during photosynthesis.
Here is Wim's video: ua-cam.com/video/jFLUEBGTac8/v-deo.html
Here is Hanks video: ua-cam.com/video/qV0udTvYK6M/v-deo.html
Here are several other videos of various desmids dividing (some in the genus Micrasterias). Several of these were briefly shown in my video:
ua-cam.com/video/0P7RQV51XvU/v-deo.html
ua-cam.com/video/llO0ZZlSGc8/v-deo.html
ua-cam.com/video/XwpFhh3Lqhs/v-deo.html
ua-cam.com/video/BC1m26CtXY0/v-deo.html
ua-cam.com/video/Uc9ppqqCMmI/v-deo.html
ua-cam.com/video/gzh5j3NJ5-Q/v-deo.html
This reminds me of how bees don't design the shape of the cells in honeycombs, but rather the hexagonal shape is determined by the physical forces exerted on them.
My explanation: For given osmotic pressure, the external force is proportional to the area but the surface tension is only proportional to the length of the perimeter. Area scales quadratically, perimeter linearly, so to preserve the force equilibrium, there is dimple formation and twinning at the surfaces to increase the perimeter to match the increase in area. Dimple forms where the stress is maximum, so that's where twinning is most likely.
Very similar things happen for crack propagation, as the crack propagates at the rayleigh velocity and can't go faster to dissipate crack energy, there is crack twinning, so we see a fractal nature of crack propagation. Its got more to do with physics at at this point.
One more thing, I remember watching Robert Sapolsky's lectures where he said that "what the gene does" is meaningless statement, but what the "gene environment interaction is" is a meaningful statement. Evo-devo is just as much physics and mechanics as it is biology.
The pop-sci "because evolution" reasoning to every question is just absurd speculation, one has to always demonstrate first what mechanism is taking place exactly before one can show how its favourable by natural selection. The shape of a micelle is not determined by evolution, its just the shape with the minimum potential energy.
The grooves probably make it easier to exchange resources with the environment as well. More surface area, more direct exchange near the center.
My first guess would be symmetry is the most favorable means (given certain developmental constraints) of surface enlargement. An asymmetrical form would maybe result in slightly less photosynthesis and would thus be selected against
Are the same genes responsable for both halves of a symmetric organisms?If so, maybe symmetry is just a way to create complexity with the least amount of information.
Have you found any experimental work corroborating your hunch such as separating the two hemi cells before growth or changing the water pressure during growth ? Tension cues can also be revealed with various microscopy technique. Maybe the models invoking molecular cues were thought of because your hunch was already proved non conclusive. Thanks for the interesting biological question anyway!
I have not seen anyone explore the tension issue and I was surprised it had not been done. I'd actually love to work with someone on it. The trick with separating them would be doing so without ripping the cells. I think messing with them in a vacuum chamber could reveal it, though.
@@StatedCasually please do check the spam filter of your channel. I've answered twice to your message with links and it seems those comments are witheld from view
For some reason links seem disabled on this account, even though they are not disabled under the settings on my channel. I've had this issue on Stated Clearly too and tried to get UA-cam support to fix it but they never responded. Not only that, I can't see your message in the "held for review" tab. Looks like they were simply deleted by UA-cam for some reason.
Try sending via twitter @statedclearly or my email and I'll post them. UA-cam lets me post links in the comments still.
Amazing video. Thank you for doing what you do. And I’m definitely gonna need an eventual John Perry and Hank Greed collaboration video one day.
I think there are multiple evolutionary and even reasons based on physics why microrganisms are spherical and symmetrical. Being spherical would require a lot less genes since it is a simple shape to grow and the material needed for cell wall growth would be equal at all sides. Locomotion may also benifit organisms that are symmetrical and symmetrical organisms better react to stimuli. And that is why the group bilateria was favored by natural selection. Thanks for the video. It is a really interesting topic.
Sir, In Gray anatomy, at cells chapter, Its written like this - Cell shape is determined by inner constitutes, similar cells interaction (Tissues) and external interaction. Along with that, Is it any specific genes for cell shape?
From what I understand your argument is essentially that the shape is a result of mainly physical forces. You mentioned that the model from the paper you discussed seemed too complicated as it assumed other interactions. My question, then, is what's stopping other cells developing the same shape? If this shape is entirely driven by the physics you outlined, what's stopping that from occurring in other cells from other species?
Of course if I've missed anything please feel free to call me out on that 😅😅
DNA sequence controls what types of proteins can be made and the timing of protein production. These proteins control the speed of wall growth, the thickness, and so on (so ultimately, the genes are controlling this). Changes in those genes will cause changes in the cell's morphology, but they do this by changing how the cell interacts with the environment. The indentations themselves are caused by a simple physical collapse of the membrane under pressure, as it interacts with the environment.
Yeah but if the invaginations are caused by this how do you explain cells that are smooth? Shape must be determined by genes.
I wonder if there has been an analysis of active / used genes in symmetrical vs asymmetrical organisms.
My hypothesis is if there is an evolutionary advantage to symmetry it would be due to concision of gene expression.
I'm curious what's going on in the 3rd dimension; why/how do they grow flat?
That's a good question. Physically I can only guess how that's done. From a selective point of view, being flat has several possible advantages, one being that it increases the surface area to volume ratio which can be good for catching more sunlight during photosynthesis.
You could basically say that it's physics that causes it and not biology inherently.