Mutations – Are all types of cells (skin, brain, reproductive) equally affected by exposure to ionizing radiation?

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The deeper the organ, the less it’s affected?

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Answer: All DNA is affected by ionizing radiation, regardless of what kind of cell it is in. But, not all cells are equally exposed. Skin cells, being on the surface, are most exposed and most likely to develop mutations as a result. But, they also have active defenses, like producing melanin to try and absorb some of that radiation before it hits the DNA.

UV light does not penetrate very far, so internal organs have zero risk of mutation from UV. But they are at risks from radiation that penetrates more deeply, like X-rays.

Ionizing radation causes damage to the existing DNA, but does not become a mutation until that DNA is copied, and the copy is “incorrect,” with the damage affecting the replication process and so giving a new strand of DNA with a different pattern of nucleotides. So while radation will damage all cell types, the ones that are mostly likely to result in mutations that lead to things like cancer are the cells that divide most often. Skin cells, blood cells, intenstinal linings, lungs, things like that. This is one reason why you never hear about muscle cancer or heart cancer, because while those cells could develop DNA damage, they divide so infrequently that it’s very very rare for that to progress to cause cancerous mutations.

So all cells are vulnerable to ionizing radation if exposed to it, but how likley that it to cause mutation depends on how frequently those cell types replicate.

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