Single cells (like bacteria or eukaryotes) are extremely complex "machines" which can take input and produce output, and generally just live life. The question is, is there any example of "trade" (as in, "commerce") between cells, or within a cell at the molecular level (trading one protein for another, or a generalized "currency" where you could trade a general thing like money for anything else? I imagine there are, but not sure if people have put cells into this mental framework before.

Receptors on a cell seem to be somewhat a form of exchange/trade, "give me a molecule and I will start this chain reaction for you". There's probably many other forms of trade in this light. But what about money/currency?

This is, generally, an open-ended question. To make it closed. Provide one complete example of trade and money, and/or link to relevant research.

  • $\begingroup$ Another example might be Rhizobium in root nodules (see here). It takes about 16 ATP to 'fix' one molecule of N2 into (2 NH3). The bacteria supply the plant with 'fixed' nitrogen, and the plant supplies the bacteria with nutrients and energy (possibly being the direct source ATP?). 'Free' Rhizobium cannot 'fix' N2. $\endgroup$
    – user338907
    Oct 5, 2021 at 4:00
  • $\begingroup$ Look into biofilms for bacterial mutualistic relationships. $\endgroup$
    – BagiM
    Oct 5, 2021 at 6:33
  • $\begingroup$ Trade or currency implies a value placed on it - as in one cell could hold out for 2 ATP vs 1 for another, which requires thought ...so no. There is exchange, but it isn't trade or currency. $\endgroup$
    – bob1
    Oct 5, 2021 at 7:52
  • $\begingroup$ Cross-feeding is a common type of symbiotic interaction in which one organism can utilize a substance produced but not utilized by another organism. It's very common in bacterial communities, and often mutualistic (though not always). But there's no perfect analog for currency in this context. More like bartering goods and services. $\endgroup$
    – MikeyC
    Oct 5, 2021 at 17:13

1 Answer 1


Lichens might be such an example. Algae living with fungi in a mutualistic relationship.

  • $\begingroup$ These are multicellular organisms, right? I am looking for single celled organisms or within single celled organisms. $\endgroup$
    – Lance
    Oct 5, 2021 at 3:55
  • $\begingroup$ @Lance Plenty of unicellular fungi combine with unicellular photosynthetic green algae or cyanobacteria to form lichens. Check out the article in my link. $\endgroup$
    – Armand
    Oct 5, 2021 at 6:20

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