Damn right you’re not. Points to Wavefunction on his corrections.

Most of your DNA cannot recombine at all, much less in the way that you describe, aside from a few fun exceptions like your antibody coding genes. Rather, there is simply a very low rate of errors durring replication. Your DNA is copied almost perfectly, and you get something like 3 errors out of 3 billion base pairs. Also, since most of your DNA is stuff like simple repeats and transposons, which do not (as far as folks have been able to tell) play a role in the survival of any given individual, most of these errors won’t even cause a ripple.

However, after ~50 divisions those errors start to pile up, and the chances of something going wrong start to rise exponentially. If something goes wrong enough to change the cell’s behavior, but not wrong enough to actually kill the cell, you potentially end up with a malignant cancer.

In terms of running out of spare parts, the only thing you have in your DNA that even vaguely fits that description are the telomeres, which do get shorter with every division in most of your cells. However, the telomeres act as a kind of fuse, causing the cell to die once it’s gone through enough divisions, helping to prevent, not cause, the kind of cancer-causing events I described above.

You mean nucleotides, not amino acids.

I’m no biologist, and that could very well be true, but my understanding was that some cancers are the result of normal cellular breakdown, and not the cause. Specifically, during DNA transcription/replication, occasionally some amino acid pairings get messed up by the transcription enzymes, leading to incorrect/faulty codons. To rectify this, our DNA contains long chains of amino acids that essentially ‘don’t code’ for anything: they’re sort of like spare parts that can be swapped in by another enzyme when the first enzyme mucks up the pairings.

Since our cells’ DNA is pretty much continuously replicating, those spare parts eventually start to run out. When they do, any further transcription errors that crop up don’t have replacements, and we end up just trying to live with them. These errors can cause all kinds of problems, including cancer. In some sense, this seems like it would explain why some cancers have a higher incidence rate among elderly people.