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I believe the components are indeed drawn to scale! The cell is a mess, there is virtually no central coordination, just individual molecular signals. A protein

by entee 8y ago

I believe the components are indeed drawn to scale! The cell is a mess, there is virtually no central coordination, just individual molecular signals. A protein gets phosphorylated by a receptor, then its on its merry way till it hits something it interacts with and maybe because it's phosphorylated it activates that thing to do something else, or maybe, luck of the draw it doesn't. It's amazing that it even works, but it does so because billions of years have shaped life to be resilient to chaos. Some context: Unicellular life is roughly 3.5B years old Eukaryotic life is roughly 2B years old. It took 1.5B years to figure out how to build and use organelles Multicellular life is roughly 1B years old. Another billion years to figure out how to coordinate and specialize cells. Sea sponges, essentially "animals" are 700M years old Animals that can move around are about 500-600M years old, backbones in animals show up around the same time, then we're off to the races. This sort of patterning is maybe in the 700-800M year old window. It took billions of years for life to figure this out, you can do a lot by evolving that long. https://www.newscientist.com/article/dn17453-timeline-the-evolution-of-life/ https://www.newscientist.com/article/dn17453-timeline-the-ev...

est31 8y ago
> A protein gets phosphorylated by a receptor, then its on its merry way till it hits something it interacts with and maybe because it's phosphorylated it activates that thing to do something else, or maybe, luck of the draw it doesn't. There are proteins that spread via diffusion, but there is also transport along microtubules in transport vesicles. Not entirely sure how the routing/navigation question is solved though, aka how does some vesicle know it needs to go to the nucleus vs golgi apparatus.
- entee 8y ago
  Oh yes, of course there are many motorized processes, but the point is there's no inherent logic to them. A myosin grabs onto a filament and goes to the plus end of the actin filament (usually, not some of them, again it gets complicated :) but it doesn't know where that tube is going. It'll just happily move to the end and fall off/get blocked. If the destination "wants" or "needs" supra-diffusion transport, it needs to recruit the tubes to come to it. Every entity in the cell essentially acts as its own agent, and it's only through interactions that it does one thing or another. EDIT: probably more accurate to call actin "filaments" not tubes, typo
  - rrock 8y ago
    Actually, there’s quite a bit of inherent logic to actomyosin traffic networks, as we’re now beginning to discover. For example, myosin 10 has evolved to walk along specific bundles of actin, but not so well along single actin filaments. The bundle has mechanical integrity and leads to a distant location in the cell, and the myosin 10 can detect that the actin is bundled. So in some sense it knows that it is walking along the right structure that leads to that distant location. There are some other examples, but this is all at the cutting edge of motility research.

by entee 8y ago

est31 8y ago

> A protein gets phosphorylated by a receptor, then its on its merry way till it hits something it interacts with and maybe because it's phosphorylated it activates that thing to do something else, or maybe, luck of the draw it doesn't. There are proteins that spread via diffusion, but there is also transport along microtubules in transport vesicles. Not entirely sure how the routing/navigation question is solved though, aka how does some vesicle know it needs to go to the nucleus vs golgi apparatus.

entee 8y ago
Oh yes, of course there are many motorized processes, but the point is there's no inherent logic to them. A myosin grabs onto a filament and goes to the plus end of the actin filament (usually, not some of them, again it gets complicated :) but it doesn't know where that tube is going. It'll just happily move to the end and fall off/get blocked. If the destination "wants" or "needs" supra-diffusion transport, it needs to recruit the tubes to come to it. Every entity in the cell essentially acts as its own agent, and it's only through interactions that it does one thing or another. EDIT: probably more accurate to call actin "filaments" not tubes, typo
- rrock 8y ago
  Actually, there’s quite a bit of inherent logic to actomyosin traffic networks, as we’re now beginning to discover. For example, myosin 10 has evolved to walk along specific bundles of actin, but not so well along single actin filaments. The bundle has mechanical integrity and leads to a distant location in the cell, and the myosin 10 can detect that the actin is bundled. So in some sense it knows that it is walking along the right structure that leads to that distant location. There are some other examples, but this is all at the cutting edge of motility research.