Biology: mitochondrial DNA, part 1: persistence

Tutoring biology, mitochondrial DNA can be a topic. The tutor begins about it.

Watching true crime shows, I believe, is where I first heard about mitochondrial DNA, aka mtDNA. It seemed to me that mtDNA might be possible to extract from a biological sample when nuclear DNA (aka nDNA) no longer is. Yet, is that true, and why?

It turns out, it seems, that indeed, mtDNA is more persistent than nDNA. This informative article by Jonathan Jarry, M.Sc., on McGill’s website says some reasons:

• A mitochondion can have 2-10 copies of its mtDNA, and there are hundreds of mitochondria per cell. With nDNA, however, there is typically only one copy per cell. Therefore, there are hundreds of times, or perhaps thousands, more chances to salvage mtDNA compared with nDNA.
• mtDNA is round, so it’s hard for enzymes that start at the end of a molecule to digest it. nDNA isn’t round, so has ends to start at.

mtDNA presents many avenues for exploration. I hope to cover more in future posts.

Source:

ncbi.nlm.nih.gov