It is known that a large fraction of the genome of almost any organism "does not work", that is, it does not encode any proteins and does not participate in gene expression, in protein synthesis, and in changes in the properties of the organism during mutations (e.g., estimates of functional DNA fraction in humans).

If you imagine an organism, for example a human, whose genome consists of completely "working" parts, what will be the consequence? For example, if all 3 billion base pairs of the human genome formed fully working genes, each of which would code for some proteins or combinations of proteins.

What would a human be like if their entire genome of 3 billion sequences consisted of coding genes?

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    $\begingroup$ Not really since the number of genes doesn't correlated with organismal complexity. Water daphnia have ~30% more genes than humans do. Going by your last couple of posts, this article may clear up some things and be of interested to you metode.org/issues/monographs/… $\endgroup$ – user438383 Jun 15 at 13:52
  • $\begingroup$ @user438383 And what correlates? And yet, what would a person be like if their entire genome (all 3 billion base pairs) were working? $\endgroup$ – Arman Armenpress Jun 15 at 13:55
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    $\begingroup$ That's impossible to answer - it's much too hypothetical, so the answer could never be known. Humans are humans because of the genes we have. It might be fun to speculate, but it' doesn't really make sense as a scientific question. $\endgroup$ – user438383 Jun 15 at 14:29
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    $\begingroup$ I think it's very important to stress that your statement It is known that most of the genome of almost any organism "does not work" is completely incorrect, as @jakebeal describes in his answer. Just because a sequence or region doesn't code for a protein gene product doesn't mean it's useless. This is a common misconception we see here, and it deserves to be vigorously refuted. $\endgroup$ – MattDMo Jun 15 at 16:54
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    $\begingroup$ As a new contributor I would encourage you to read the guidelines on what sort of questions one should avoid asking here. If you do so I think you will realize why I think that this is one of them. $\endgroup$ – David Jun 15 at 16:58

Your question is closely related to the concept of minimal genomes, in which researchers attempt to understand the significance of genes by removing everything that isn't strictly necessary, which includes "broken" genes, redundant genes, intergenic regions, etc.

The typical result is a much more fragile and less functional organism. Much of this is due to the fact that "not strictly necessary" is not the same as "not useful." However, there is also a lot of regulatory function outside of coding sequences, as well as implicit and unknown functionality in apparently "non-functional" DNA.

Examples of this include spacing between genes that interacts with histone positioning, decouples methylation, or other epigenetic factors, spacing that couples or decouples genes, sequences with functions that haven't been discovered yet.

So what would happen if you had a human with either all of the "excess" material removed or with the "empty" material filled in with extra genes with some intended function? In either case, you'd probably never actually end up with a human, because the resulting organism would be so fragile and impaired by undesirable interactions due to the loss of genetic separation, that it would never even be able to make it past the embryo stage to become a fetus.

  • $\begingroup$ Very likely the all genes active is going to be a mass of stem cells. So more of a cancer than human. $\endgroup$ – Roni Saiba Jun 15 at 15:53
  • $\begingroup$ @jakebeal Why will it be fragile? Additional genes implies coding for new forms of proteins, about which we know nothing (after all, the space of proteins is huge and grows with the number of amino acids). Maybe there will be proteins that make the body not fragile, but quite the opposite? $\endgroup$ – Arman Armenpress Jun 15 at 15:57
  • $\begingroup$ @RoniSaiba <Very likely the all genes active is going to be a mass of stem cells>. Why do you think so? $\endgroup$ – Arman Armenpress Jun 15 at 15:58
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    $\begingroup$ @ArmanArmenpress A genome is more than just proteins. The regulation of those proteins is critical as well, and "empty space" is part of that regulation. Break the regulation and break the organism. $\endgroup$ – jakebeal Jun 15 at 16:37
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    $\begingroup$ @ArmanArmenpress Embryonic stem cells have the highest euchromatin to heterochromatin ratios. As cell become more specialized i.e. differentiate, they start shutting down unnecessary (for them) regions of the genome. I think Gilbert's Developmental Biology will be a book that will satisfy your curiosity. $\endgroup$ – Roni Saiba Jun 16 at 1:48

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