I understand that there are several challenges associated with horizontal gene transfer, including the risk of the transferred genes causing life threating diseases. Eukaryotes, like humans, have mechanisms to control gene transfer. Why can’t these mechanisms prevent the transfer of harmful genes and allow for beneficial horizontal gene transfer? Why haven’t humans developed this feature through evolution? Could we see this feature in future human generations( after a few billion years)?
Note: There are a few studies that talks about HGT in humans.
In: Biology
Our DNA is wrapped up in very tight chromosomes, which are protected in the nucleus. Our DNA never leaves the nucleus. It has no opportunity to be shared directly with other cells. Bacteria, on the other hand, have DNA just kind of floating around in their cells. Some of this is in chromosome form. Some is just in “plasmids” which are like little bubbles that carry stuff around the cell. Bacteria can trade plasmids, including the DNA that’s inside them. This allows rapid evolution, but also presents the risky opportunity for things to get messed up easily, resulting in high death rates too. But it’s bacteria which can multiply super rapidly, so higher death rates aren’t as big of a deal.
An important thing to know about evolution is that it’s not “forward thinking”. It can’t imagine an ideal organism and make choices to get to that goal. It can only work with what it has. And other trade-offs/adaptations over time have led to how our body is. We can survive just fine in order to reproduce, and that’s all natural selection cares about. Cancer/disease in our 40s and later? Doesn’t really matter, we’re past reproductive age. Of course now we can overcome natural selection to some degree with medicine, but completely rewiring the way our cells function is not in the near-future of possibilities.
It can happen in humans, it’s just way more rare. Think of something like Kaposi’s sarcoma, or something similar. It’s a numbers game (and most multicellular organisms have mechanisms to mitigate the risk) but it still happens. The other reply explains things, but it does happen.
https://en.m.wikipedia.org/wiki/Pilus
Bacteria have specific structures that let them connect with other bacteria and send DNA over.
First and foremost, they’re unicellular. That’s sort of a big point.
So what if one of few billion cells in a human body catches some foreign DNA? But if you only have the one, it matters.
Two, unlike eukaryotes (us) who have their DNA safely put away in the nucleus, bacterial DNA sort of floats there, easily accessible. That makes both cutting bits out and inserting bits much easier, making the HGT much more likely to occur.
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