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Ionizing radiation is damaging to DNA, but is there such a thing as a safe dose below which no DNA damage could occur? I'm not asking about a minimum safe dose overall, just whether or not there's an amount of ionizing radiation so small that the cell wouldn't even "notice" it if it were absorbed. Suppose I have, say, a fertilized egg cell on a petri dish. Would a single stray x-ray photon absorbed by the cell be enough to destroy it before it could reproduce? Is most DNA damage from x-rays due to the action of single photons, or from multiple ones being absorbed at the same time?

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closed as too broad by WYSIWYG, The Last Word, user137, Chris, ddiez Dec 6 at 10:27

There are either too many possible answers, or good answers would be too long for this format. Please add details to narrow the answer set or to isolate an issue that can be answered in a few paragraphs.If this question can be reworded to fit the rules in the help center, please edit the question.

    
The problem with answering your question accurately is, one, the absorption of a phtoton is a quantum mechanical phenomenon with almost a random chance of happening, and two, once absorbed, a lot of photophysical processes can occur, mutation being only a small part of the available options. Thus, yo quantify the threshold amount of radiation for mutation might not be possible because a lot of variables are involved. –  Satwik Pasani Feb 5 at 2:46
    
Interesting. I had thought it was as simple as the ionization energies of the atoms in DNA, but I guess I was wrong. –  Joel Feb 5 at 3:09
    
I think its possible - specifically if the photon caused a particular DNA break which was not reparable by the Cell's defenses, but that would be incalculably rare. Even most DNA breaks are repaired without incident. –  shigeta Feb 5 at 14:38

1 Answer 1

The problem with answering your question accurately is, one, the absorption of a phtoton is a quantum mechanical phenomenon with almost a random chance of happening, and two, once absorbed, a lot of photophysical processes can occur, mutation being only a small part of the available options. Thus, to quantify the threshold amount of radiation for mutation might not be possible because a lot of variables are involved.

          —  Satwik Pasani

I think its theoretically possible - specifically if the photon caused a particular DNA break which was not reparable by the Cell's defenses, but that would be incalculably rare. Even most DNA breaks are repaired without incident.

          —   Shigeta

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