6 ms·

The Weight of a Cell

91 points by arbesman 1y ago

lblume 1y ago
> Cells are physical objects This might sound trivial, but in me sparks a much larger point: which kinds of experimental designs and tests might we miss when engaging in a special science? In establishing dedicated methods I think it's highly likely for there to be low-hanging fruits of experimental setups not considered due to prevalence of these very specific frameworks.
- jcims 1y ago
  Not sure I am tracking your point entirely, but any time I start digging into a new domain I regularly find that the language peculiar to that topic can hide concepts that are broadly familiar and, in part, exacerbate the problem that (I think) you are describing.
Metacelsus 1y ago
Very cool. I wonder how the accuracy of weighing a single cell would compare to counting a huge number of cells (let's say 10^9) and doing a bulk weight measurement. The problem would shift to being able to accurately count cells, and being able to exclude the effects of liquid trapped in between the cells.
shauniel 1y ago
Asimov really is a breath of fresh air. Love their content
atombender 1y ago
> A typical kitchen scale has a sensitivity of 0.1 grams As someone who's been looking for a good kitchen scale, your typical kitchen scale is actually precise to then nearest gram at best, and in terms of precision it's probably not very precise at all. 0.1g is rare, and these usually cost more, especially if they're actually reliable.
- madcaptenor 1y ago
  I hadn't thought about this, but this is probably why in baking recipes where amounts of flour, sugar, etc. are specified by weight, baking powder and any spices will be specified by volume. Of course this is all false precision once you start adding eggs.
  - duped 1y ago
    imo the reason to bake by weight is because the ratios of the major ingredients (flour, fat, sugar, and water) determines the properties of the dough, and it's impossible to measure by volume reliably (especially flour, which is the largest ingredient by weight in most recipes). Meanwhile you don't have to be precise with baking soda or yeast. Mix-ins like herbs are completely to taste. Salt could go either way. Recipes absolutely adjust for the weight of the eggs and some rules of thumb for water and fat content. But that said, a chicken egg is like 55g with 10% tolerance (at least the eggs I buy, and I do everything by weight). 5g of mostly water one way or the other doesn't have a massive amount of impact on the dough, and you can always adjust based on feel after mixing. At scale everything is measured by weight fairly precisely. But you really don't care about accuracy, since it's the ratios of ingredients that make the product and not the raw amounts.
  - privatelypublic 1y ago
    Eggs are actually fairly well defined on weight. And absolutely are better defined than things like flour where a volumetric cup can be 4oz or 12oz (or more) depending on how fluffed the flour is and individual scouping technique.
- mlinhares 1y ago
  They're not even that expensive anymore, you can find pretty reasonably priced ones: https://www.amazon.com/dp/B0D66X8B5B/ref=sspa_dk_detail_2?pd_rd_i=B0D66X8B5B&pd_rd_w=jwWby&content-id=amzn1.sym.386c274b-4bfe-4421-9052-a1a56db557ab&pf_rd_p=386c274b-4bfe-4421-9052-a1a56db557ab&pf_rd_r=GH6DV8AF7DCCKK1JWXW0&pd_rd_wg=ME9sK&pd_rd_r=68b461c7-1748-490f-82ad-d6f9e6509740&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWxfdGhlbWF0aWM&th=1 https://www.amazon.com/dp/B0D66X8B5B/ref=sspa_dk_detail_2?pd... I have the ooni one that i use for my baking and to measure yeast and it was one of the best investments i made.
franciscop 1y ago
Some surprising science fact that many people don't know, an animal egg (chicken, birds, etc) is a single cell, so there's a huge variability in the weight of a cell.
- btilly 1y ago
  I found this claim unbelievable, but it is mostly true. It isn't quite the whole egg, it is just the yolk. But that's still a very large cell! http://cnet.com/home/kitchen-and-household/appliance-science-the-biology-of-the-chicken-egg/ http://cnet.com/home/kitchen-and-household/appliance-science... verifies this.
  - madcaptenor 1y ago
    It's analogous to the mammalian egg, but a lot bigger. (And IIRC the egg is the largest cell in humans.)
    - IAmBroom 1y ago
      And the smallest is the sperm. Which, ironically, are both only haploid.
  - Davidzheng 1y ago
    i guess if it's fertilized then it will soon have more cells
- mr_toad 1y ago
  There are some very large single celled organisms that aren’t eggs. E.g.: https://en.wikipedia.org/wiki/Valonia_ventricosa https://en.wikipedia.org/wiki/Valonia_ventricosa https://en.wikipedia.org/wiki/Foraminifera https://en.wikipedia.org/wiki/Foraminifera Even some bacteria can grow to visible size: https://en.wikipedia.org/wiki/Thiomargarita_magnifica https://en.wikipedia.org/wiki/Thiomargarita_magnifica There are some other examples here: https://en.wikipedia.org/wiki/Largest_organisms https://en.wikipedia.org/wiki/Largest_organisms
ridgeguy 1y ago
Cool results and methods, but I'll disagree with one of the article's statements. In talking about the work done on e. coli, a non spherical cell, it says the methods had to be changed due to "turbulence" attendant to the e. coli's departure from sphericity of the earlier tested yeast cells. My rough calcs show a Reynolds number in the range of 1e-6. The onset of turbulence happens at Reynolds numbers of ~2300 for pure water. The 1% sugar solution would have a negligibly higher turbulence onset Reynolds number. I expect the need for different methodology wasn't turbulence, but the difference in drag presented by an elongated e. coli compared to a spherical yeast cell.
Scene_Cast2 1y ago
I've built a scale with a kHz sampling rate and gram precision at +/-100kg range. One thing I found out is that getting calibrated accuracy beyond 0.1% is hard and expensive despite having all that precision.
- SeanSullivan86 1y ago
  What happens when something is put on the scale while it's sampling? Does the curve depend on properties of the scale, or just properties of the object and the manner in which it was put on the scale?
  - Scene_Cast2 1y ago
    It's the latter. The scale is meant for real-time monitoring of rapidly varying force (the primary application is about monitoring the force derivative and repeatable max force logging). It uses an aluminum load cell if you're familiar with those, there's a tad of a multi-kHz resonance that is typically overshadowed by the object properties.
- rolph 1y ago
  use a resonant determination of mass. https://www.nature.com/articles/nnano.2012.42 https://www.nature.com/articles/nnano.2012.42 https://arstechnica.com/science/2012/04/measuring-yoctogram-scale-masses-with-carbon-nanotubes/ https://arstechnica.com/science/2012/04/measuring-yoctogram-...
  - rcxdude 1y ago
    These are very sensitive but they are likely not calibrated to within 0.1%, and certainly it's not easy to transfer this up several orders of magnitude withiut introducing huge errors.
scheisshausDan 1y ago
[flagged]
MinimalAction 1y ago
This seems like the non-Substack link: https://press.asimov.com/articles/cell-weight https://press.asimov.com/articles/cell-weight.

91 points by arbesman 1y ago

> Cells are physical objects This might sound trivial, but in me sparks a much larger point: which kinds of experimental designs and tests might we miss when engaging in a special science? In establishing dedicated methods I think it's highly likely for there to be low-hanging fruits of experimental setups not considered due to prevalence of these very specific frameworks.

jcims 1y ago
Not sure I am tracking your point entirely, but any time I start digging into a new domain I regularly find that the language peculiar to that topic can hide concepts that are broadly familiar and, in part, exacerbate the problem that (I think) you are describing.

Metacelsus 1y ago

Very cool. I wonder how the accuracy of weighing a single cell would compare to counting a huge number of cells (let's say 10^9) and doing a bulk weight measurement. The problem would shift to being able to accurately count cells, and being able to exclude the effects of liquid trapped in between the cells.

shauniel 1y ago

Asimov really is a breath of fresh air. Love their content

atombender 1y ago

> A typical kitchen scale has a sensitivity of 0.1 grams As someone who's been looking for a good kitchen scale, your typical kitchen scale is actually precise to then nearest gram at best, and in terms of precision it's probably not very precise at all. 0.1g is rare, and these usually cost more, especially if they're actually reliable.

madcaptenor 1y ago
I hadn't thought about this, but this is probably why in baking recipes where amounts of flour, sugar, etc. are specified by weight, baking powder and any spices will be specified by volume. Of course this is all false precision once you start adding eggs.
- duped 1y ago
  imo the reason to bake by weight is because the ratios of the major ingredients (flour, fat, sugar, and water) determines the properties of the dough, and it's impossible to measure by volume reliably (especially flour, which is the largest ingredient by weight in most recipes). Meanwhile you don't have to be precise with baking soda or yeast. Mix-ins like herbs are completely to taste. Salt could go either way. Recipes absolutely adjust for the weight of the eggs and some rules of thumb for water and fat content. But that said, a chicken egg is like 55g with 10% tolerance (at least the eggs I buy, and I do everything by weight). 5g of mostly water one way or the other doesn't have a massive amount of impact on the dough, and you can always adjust based on feel after mixing. At scale everything is measured by weight fairly precisely. But you really don't care about accuracy, since it's the ratios of ingredients that make the product and not the raw amounts.
- privatelypublic 1y ago
  Eggs are actually fairly well defined on weight. And absolutely are better defined than things like flour where a volumetric cup can be 4oz or 12oz (or more) depending on how fluffed the flour is and individual scouping technique.
mlinhares 1y ago
They're not even that expensive anymore, you can find pretty reasonably priced ones: https://www.amazon.com/dp/B0D66X8B5B/ref=sspa_dk_detail_2?pd_rd_i=B0D66X8B5B&pd_rd_w=jwWby&content-id=amzn1.sym.386c274b-4bfe-4421-9052-a1a56db557ab&pf_rd_p=386c274b-4bfe-4421-9052-a1a56db557ab&pf_rd_r=GH6DV8AF7DCCKK1JWXW0&pd_rd_wg=ME9sK&pd_rd_r=68b461c7-1748-490f-82ad-d6f9e6509740&sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWxfdGhlbWF0aWM&th=1 https://www.amazon.com/dp/B0D66X8B5B/ref=sspa_dk_detail_2?pd... I have the ooni one that i use for my baking and to measure yeast and it was one of the best investments i made.

franciscop 1y ago

Some surprising science fact that many people don't know, an animal egg (chicken, birds, etc) is a single cell, so there's a huge variability in the weight of a cell.

btilly 1y ago
I found this claim unbelievable, but it is mostly true. It isn't quite the whole egg, it is just the yolk. But that's still a very large cell! http://cnet.com/home/kitchen-and-household/appliance-science-the-biology-of-the-chicken-egg/ http://cnet.com/home/kitchen-and-household/appliance-science... verifies this.
- madcaptenor 1y ago
  It's analogous to the mammalian egg, but a lot bigger. (And IIRC the egg is the largest cell in humans.)
  - IAmBroom 1y ago
    And the smallest is the sperm. Which, ironically, are both only haploid.
- Davidzheng 1y ago
  i guess if it's fertilized then it will soon have more cells
mr_toad 1y ago
There are some very large single celled organisms that aren’t eggs. E.g.: https://en.wikipedia.org/wiki/Valonia_ventricosa https://en.wikipedia.org/wiki/Valonia_ventricosa https://en.wikipedia.org/wiki/Foraminifera https://en.wikipedia.org/wiki/Foraminifera Even some bacteria can grow to visible size: https://en.wikipedia.org/wiki/Thiomargarita_magnifica https://en.wikipedia.org/wiki/Thiomargarita_magnifica There are some other examples here: https://en.wikipedia.org/wiki/Largest_organisms https://en.wikipedia.org/wiki/Largest_organisms

ridgeguy 1y ago

Cool results and methods, but I'll disagree with one of the article's statements. In talking about the work done on e. coli, a non spherical cell, it says the methods had to be changed due to "turbulence" attendant to the e. coli's departure from sphericity of the earlier tested yeast cells. My rough calcs show a Reynolds number in the range of 1e-6. The onset of turbulence happens at Reynolds numbers of ~2300 for pure water. The 1% sugar solution would have a negligibly higher turbulence onset Reynolds number. I expect the need for different methodology wasn't turbulence, but the difference in drag presented by an elongated e. coli compared to a spherical yeast cell.

Scene_Cast2 1y ago

I've built a scale with a kHz sampling rate and gram precision at +/-100kg range. One thing I found out is that getting calibrated accuracy beyond 0.1% is hard and expensive despite having all that precision.

SeanSullivan86 1y ago
What happens when something is put on the scale while it's sampling? Does the curve depend on properties of the scale, or just properties of the object and the manner in which it was put on the scale?
- Scene_Cast2 1y ago
  It's the latter. The scale is meant for real-time monitoring of rapidly varying force (the primary application is about monitoring the force derivative and repeatable max force logging). It uses an aluminum load cell if you're familiar with those, there's a tad of a multi-kHz resonance that is typically overshadowed by the object properties.
rolph 1y ago
use a resonant determination of mass. https://www.nature.com/articles/nnano.2012.42 https://www.nature.com/articles/nnano.2012.42 https://arstechnica.com/science/2012/04/measuring-yoctogram-scale-masses-with-carbon-nanotubes/ https://arstechnica.com/science/2012/04/measuring-yoctogram-...
- rcxdude 1y ago
  These are very sensitive but they are likely not calibrated to within 0.1%, and certainly it's not easy to transfer this up several orders of magnitude withiut introducing huge errors.

scheisshausDan 1y ago

[flagged]

MinimalAction 1y ago

This seems like the non-Substack link: https://press.asimov.com/articles/cell-weight https://press.asimov.com/articles/cell-weight.