Mitochondrial genes are located in multiple DNA circles in every mitochondrion. These circles of DNA hold the genes for 37 of the molecules and enzymes that the mitochondria use to capture, store and distribute energy. The complex internal structure of folded membranes in the mitochondria hold a large variety of enzymes. Enzymes are proteins which act as catalysts. They are essential to our cell biochemistry.
Many enzymes require a specific mineral to work.
Compared to a spermatozoa, the human egg is gigantic. A human egg contains thousands of mitochondria, while a spermatozoa contains only one. This mitochondrion will never enter the egg. The chromosomal genes in the head of the spermatozoa are all that a baby will inherit from the father. All mitochondria and their genes come solely from the mother in that maternal egg.