I recently watched this fantastic lecture and I was spellbound. If you don’t know basic cell biology (nucleus, chromosomes, cell membrane), you’ll be lost (and probably bored, because it’s a whole hour); but if you like biology, and you want to know why some genetic conditions which could affect a variety of body parts, don’t actually affect everything in everyone who has that allele — go get a mug of tea and watch this!
Or ask me about heteroplasmy it when you see me.