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> Cell sizes are not fixed, however, even within a single species. Cells often swell as they increase their production of proteins and metabolites in preparatio

> Cell sizes are not fixed, however, even within a single species. Cells often swell as they increase their production of proteins and metabolites in preparation for division. This is in line with biology’s only rule: namely, there are exceptions to every rule! > Case in point: a giant bacterium called Thiomargarita magnifica can extend about one centimeter in length, so large that it can be seen by the naked eye. It does so by breaking the surface area-to-volume rule, filling between 65–80 percent of its internal volume with an empty vacuole. In other words, it pushes most of its molecules to the cell periphery, thus shortening diffusion distances. There is also a captioned image of bubble algae in the post.

cwmoore 3mo ago
Interesting topology. How empty is the vacuole?
- trumpdong 3mo ago
  empty in terms of normal cell components, apparently it stores relatively huge amounts of nitrates that are a necessary energy source for it
  - magicalhippo 3mo ago
    Rather large gas tank: Collected and stored sediment samples were found to have surviving T. namibiensis cells after over two years. The cells had no access to any added sulfide or nitrate during this time. In the surviving cells, there was a notable size decrease. To survive without growing the cells depended on the nutrient stores of the central vacuoles.
    - trumpdong 3mo ago
      Indeed. It says they rely on two different substances which normally don't mix (nitrates and sulfites), presumably because if they were both present at the same time they'd react with each other directly without the bacterium extracting any energy from that. So they live in places that sometimes have one and sometimes the other, and have to store one of them until the other comes along, which can be years. Or that's how I read it.
vasco 3mo ago
> This is in line with biology’s only rule: namely, there are exceptions to every rule! Nice paradox

cwmoore 3mo ago

Interesting topology. How empty is the vacuole?

trumpdong 3mo ago
empty in terms of normal cell components, apparently it stores relatively huge amounts of nitrates that are a necessary energy source for it
- magicalhippo 3mo ago
  Rather large gas tank: Collected and stored sediment samples were found to have surviving T. namibiensis cells after over two years. The cells had no access to any added sulfide or nitrate during this time. In the surviving cells, there was a notable size decrease. To survive without growing the cells depended on the nutrient stores of the central vacuoles.
  - trumpdong 3mo ago
    Indeed. It says they rely on two different substances which normally don't mix (nitrates and sulfites), presumably because if they were both present at the same time they'd react with each other directly without the bacterium extracting any energy from that. So they live in places that sometimes have one and sometimes the other, and have to store one of them until the other comes along, which can be years. Or that's how I read it.

vasco 3mo ago

> This is in line with biology’s only rule: namely, there are exceptions to every rule! Nice paradox