When we eat food I heard that our digestive enzymes disassemble the DNA of the eaten cells so that the DNA cannot affect us. Then, is there any mechanism (that prevents the eaten cell's DNA from affecting us genetically) in cell-scale level? Or is it only in organ-system level(e.g. digestive system)? It seems that germs and viruses don't have the mechanism, as we manipulate them as genetic transferor. But I want to know if nucleate cells have the mechanism.

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    $\begingroup$ Possible duplicate of Do we consume dna, proteins of other organisms? $\endgroup$
    – kmm
    Mar 15 '18 at 1:38
  • $\begingroup$ @kmm You may be right and your link has nice answers, but my question's key point is about cell-scale level, so I think it a bit diffrerent. But if nuclease and cell membranes are only mechanisms then my question can be duplicate either.. $\endgroup$ Mar 15 '18 at 5:23
  • $\begingroup$ While not required for your main question: Viruses (and bacterial viruses) can have a stringent coupling of particle size and amount of DNA, which can prevent the inclusion of large pieces of foreign DNA (a practical problem for the early days of genetic engineering / cloning). $\endgroup$
    – tsttst
    Mar 15 '18 at 5:35
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    $\begingroup$ @tsttst I didn't know that! So your comment can be one way that primitive creatures like viruses use to prevent foreign DNA from interfering with its oen. $\endgroup$ Mar 15 '18 at 5:40

Cells have cell membranes and sometimes cell walls that keep random molecules from entering the cell. Only small, uncharged molecules can pass freely through the membrane. Complex structures of proteins embedded in the cell membrane regulate the passage of charged or large molecules. Pathogens like viruses or bacteria have had developed equally complex structures of proteins that can fool the proteins in the cell membrane to gain access to the interior of the cell. In other words, the cell membrane is almost always going to keep naked DNA from entering the cell, but viruses can get around this, by packaging their DNA in protein capsules that can compromise the cell membrane.

To create GMO, viruses are often used to transport the foreign DNA into the cell. Alternatively, the cell membrane can be attacked with chemicals, high voltages, or even mechanically punched holes, that allow DNA to pass through the membrane.

Bacterial cells will sometimes allow the passage of naked DNA, but this is very rare in plant and animal cells.

  • $\begingroup$ So you mean that it happens at digestive organ system level with nuclease? $\endgroup$ Mar 15 '18 at 5:18
  • $\begingroup$ I have no idea what you mean by that. All cells have cell membranes, it part of what makes them cells. $\endgroup$ Mar 15 '18 at 5:29
  • $\begingroup$ A ha, then outside of the cell the DNA is broken into smaller structures so that the cannot activate, and even unbroken DNA is blocked by cell membranes. Then can DNA injected by means you mentioned activate inside the cell's membrane? $\endgroup$ Mar 15 '18 at 5:36
  • $\begingroup$ @KYHSGeekCode Yes, it should. In fact that is how transfection works. Link - en.wikipedia.org/wiki/Transfection $\endgroup$
    – Roni Saiba
    Mar 21 '18 at 16:02
  • $\begingroup$ @RoniSaiba I did well to adopt yours. Thanks! $\endgroup$ Mar 21 '18 at 16:04

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