Regarding the origin of mitochondria, Bi Fang knew of a very interesting hypothesis.
Mitochondria used to be bacterial organelles in eukaryotic cells and have an endosymbiotic relationship with humans.
Simply put, a long, long time ago, mitochondria were independent organisms that, by chance, combined with humans and eventually became part of the human body.
To this day, they still maintain a certain degree of "independence."
Evidence of this is that mitochondria and the human genome are entirely different matters.
The mitochondrial genome is 16,569 in length, encoding 37 genes, mainly related to the respiratory chain.
The human nuclear genome is 3 billion in length, encoding 20-30 thousand genes, including all content.
There is no homology between the two sequences.
And the genomes of other tissues within the human body are all from the human nuclear genome.