system
Given the following post, respond as if you're commenting on Reddit:
human
What happens to a molecule which has an element which is part of its construction reach its half life?

For example, Carbon-14 has a half life of about 5730 years per Wikipedia, and since Carbon is a major building block of life C14 has found its way into all organic life on Earth in the same concentrations as we find in our atmosphere.  So what happens, for example, when one of these C14 elements reaches its half life in a molecule of an amino acid within our own DNA?
gpt
What you'd expect, ultimately. 

For starters, radioactive decay is more random than you're saying here. It's statistical. It's not that each Carbon-14 atom decays every 5730 years. It's that half the atoms in a clump of Carbon-14 decay every 5730 years. If you're watching one, it might decay in two weeks. It might be 20,000 years. No way to know.

Anyway, though, Carbon-14 decays into Nitrogen-14, with an electron and an antineutrino. CO2 is stable, now you've got NO2. It behaves like NO2 would anywhere else. More complex molecules may not be stable at all, and fall apart.

But lucky for you, you've got a LOT of carbon atoms in your body, and you don't live 5730 years. And the carbon in your body doesn't stick around your whole life. So you might lose a few amino acids to radioactive decay here and there, but it's not enough to hurt you.