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Why are cells small?

burrito.bio

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Re: Why are cells small?

#81

Post by chasil »

shevy-java wrote: post #65
teravor wrote: post #42

Earlier quoted context omitted.

> The entire cell contains several cytoplasmic domains, with each domain having a nucleus and a few chloroplasts. it reinvented being multi-cellular

Agreed. Humans draw rather arbitrary distinctions. It was quite funny in regards to viruses, aka parasite. Mimivirus are still a parasite, of course, but they even encode genes for metabolic pathways and are larger than some bacteria. See: "The Mimivirus is a giant virus that infects amoebae and was long considered to be a bacterium due to its size." https://pmc.ncbi.nlm.nih.gov/articles/PMC9133948/ Although for me,…

Perhaps what you are seeking "retrotransposons," an endogenous retrovirus.

https://en.wikipedia.org/wiki/Retrotransposon#Endogenous_ret...

Re: Why are cells small?

#82

Post by [deleted] »

shevy-java wrote: post #65
teravor wrote: post #42

Earlier quoted context omitted.

> The entire cell contains several cytoplasmic domains, with each domain having a nucleus and a few chloroplasts. it reinvented being multi-cellular

Agreed. Humans draw rather arbitrary distinctions. It was quite funny in regards to viruses, aka parasite. Mimivirus are still a parasite, of course, but they even encode genes for metabolic pathways and are larger than some bacteria. See: "The Mimivirus is a giant virus that infects amoebae and was long considered to be a bacterium due to its size." https://pmc.ncbi.nlm.nih.gov/articles/PMC9133948/ Although for me,…

[deleted]

Re: Why are cells small?

#83

Post by tsoukase »

All life started from procaryotic cells. The step from macromolecules to the first cell cannot be big, otherwise it could not happen spontaneously. On the other side, it must be big enough so that the cell have enough flexibility and functionality to support complex life.

That is, the cell is small enough in order to be produced directly by molecules but large enough in order to be a full living organism (reproduction, metabolism etc). This sweet spot seems to be the cell size we observe.

Later in evolution the size disparity grew because a procaryotic cell swallowed another one to become an eucaryotic and the eucaryotic ones specialized even further.

Re: Why are cells small?

#84

Post by trumpdong »

magicalhippo wrote: post #78
trumpdong wrote: post #54

Earlier quoted context omitted.

empty in terms of normal cell components, apparently it stores relatively huge amounts of nitrates that are a necessary energy source for it

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.

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.

Re: Why are cells small?

#85

Post by IAmBroom »

CrazyStat wrote: post #40
limbero wrote: post #7

Nitpick maybe, but I don't think oocytes are the largest cells, it pretty much has to be some sort of neuron. A sensory neuron for eg. someplace in the foot will be almost as long as the person is tall, and even if the neuron is extremely thin, it's gotta beat the oocyte for volume.

Giraffes neurons can be up to 15 feet long. Blue whales are speculated to have neurons up to 100 feet long, though they've never been directly observed (dissected).

They've been catastrophically dissected at least once, which we know due to the detailed field notes made by Paul Linnman, and subsequent citations by Dave Barry.

It's possible some of them were observed, given the likelihood of striking someone's glasses or windshield.

Re: Why are cells small?

#86

Post by IAmBroom »

BurningFrog wrote: post #47

Cells are small compared to humans because we're made up by around 3×10¹³ cells.

An odd way to look at it.

Why do our bodies constrain everything else? Sure, WE are big in cell-units, but why are cell-units in the size range they are?

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