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After searching "do antibiotics impact the immune system" I found out that antibiotics target prokaryotic cells. It all made a lot of sense thinking about all those yogurt recommendations you get after taking antibiotics: the collateral damage is on the prokaryotic cells that live with us, but are not "us" as such.

Except I remembered human red blood cells don't have nuclei, so where's my confusion?

(I'm only a biology enthusiast.)

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Are red blood cells prokaryotic?

No!

  1. There are many more differences between procaryotes and eukaryotes than just the presence of a nucleus. See DeNovo's answer for more information.

  2. The terms procaryote vs eukaryote refer, not so much to the physiology of the cell but to a specific evolutionary lineage. Eukaryotes are individuals that belong to the monophyletic group of Eukaryota aka. Eukarya (see here for an intro to phylogeny). As such whether or not a eukaryotic loses its nucleus and start looking exactly like a E. coli won't change anything to the fact that this cell is still in the Eukaryota lineage.

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When differences between prokaryotes and eukaryotes are taught in an introductory biology course, a generic prokaryotic cell and a generic eukaryotic cell are typically compared. Cells in a complex multicellular organism, like a human, are quite diverse. Human red blood cells are one example of a highly specialized cell with a mature form that is quite different from the typical eukaryotic cell. Keratinocytes in the epidermis are another example (see Ross Histology, Ch. 15). In both cases, these cells produce large amounts of a single protein, eventually, at their most mature stage, stopping protein synthesis, extruding their nuclei and most other organelles.

The absence of a nucleus or other organelles, however, does not necessarily make either of these cells more susceptible to antibacterial antibiotics. Antibiotics are targeted toward things that bacteria have (positive differences), rather than the absence of typical eukaryotic structures. Almost all antibacterial antibiotics have one of three targets (see Goodman and Gilman Chs. 48, 52-55):

  • The bacterial cell wall or membrane

  • protein synthetic machinery

  • specialized metabolites required by bacteria

There is (almost) no overlap between these structures in bacteria and structures in any of the diverse array of human cells. The one partial exception is a similarity between the mitochondrial and bacterial ribosome, that may, for example, be responsible for some of the toxicity of chloramphenicol (G&G Ch. 55).

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    $\begingroup$ "antibacterial antibiotics" - never heard antibiotic qualified in this way. What's an example of an antibiotic whose intended target is a microorganism other than a bacteria? $\endgroup$ – bishop Aug 5 '18 at 4:27
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    $\begingroup$ @bishop antifungal and antiviral therapies both qualify as antibiotics. They have different targets, based on the properties of pathogenic viruses and fungi. $\endgroup$ – De Novo supports GoFundMonica Aug 5 '18 at 4:56
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No. Prokayotic cells are full organisms with their own DNA, red blood cells are not.

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    $\begingroup$ It's also hard to even call them living things, since they do not do most of what living organisms do. They are just half dead components with a single purpose: zombies so to speak. $\endgroup$ – Daniel Goldman Aug 2 '18 at 19:18
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    $\begingroup$ @DanielGoldman thats not true. They consume organic matter, they reproduce, they have their own genetic instructions that produces proteins. What don't bacteria do that you would not consider them alive? $\endgroup$ – Jamie Clinton Aug 2 '18 at 20:50
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    $\begingroup$ @JamieClinton he meant mature RBCs, which don't do what most living organisms do. They fulfill more than a single purpose, but otherwise, he's exactly correct. Once they reach maturity, they don't synthesize any more protein and can't reproduce. $\endgroup$ – De Novo supports GoFundMonica Aug 2 '18 at 21:40
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    $\begingroup$ Gotcha. Although I wouldn't call a cell in a multi-cellular being a 'living organism' regardless. $\endgroup$ – Jamie Clinton Aug 2 '18 at 21:43
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    $\begingroup$ @swbarnes2 That's not at all what I'm saying. Many attempts to define life start by considering reproduction. I was pointing out the problem with that, exactly because it is ridiculous and disgusting to consider an infertile individual to be a non living thing. I'm honestly shocked that someone would somehow interpret my comment as the converse (because these people are useless garbage, we can safely say that's a good way to classify cells). How would anyone think that? $\endgroup$ – De Novo supports GoFundMonica Aug 3 '18 at 23:06
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No, they are matured (broken) reticulocytes without the net structure and ribosomal DNA, which themselves are matured (broken) normoblasts that have lost their nucleus.

So basically they're the left over plasma membrane of a once-alive eukaryote cell, now filled with mostly hemoglobin, and little else.

(The above is not necessarily true for all animals, some have nuclei, but it's the case for mammals, and thus humans.)

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    $\begingroup$ Erythrocytes have very complex metabolism and maintain internal homeostasis. It's not fair to say that they are "once-alive, filled with hemoglobin and little else" considering they are still living cells. $\endgroup$ – forest Aug 4 '18 at 7:02

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