Mitochondria

A mitochondrion is an organelle — a compartment inside a cell — with two membranes. The inner one is deeply folded, which packs a large surface area into a small volume, and that surface is where the energy work happens.

Cells hold anything from a handful to several thousand, roughly in proportion to how much energy they use: heart muscle and neurons are densely packed with them.

Mitochondria carry a small circular genome of their own, separate from the DNA in the nucleus. Because sperm contribute essentially none at fertilisation, a person’s mitochondrial DNA comes from their mother.

Cells run on ATP, a molecule that stores energy in a form the rest of the cell can spend. Mitochondria are where the great majority of it is made.

Nutrients broken down elsewhere in the cell are fed into a cycle of reactions inside the mitochondrion, which strips off high-energy electrons. Those electrons are passed down a chain of proteins in the folded inner membrane, and the energy released is used to pump protons across that membrane.

That builds up a gradient — more protons on one side than the other — and the protons flow back through a molecular turbine that spins as they pass, and that rotation is what manufactures ATP. Oxygen’s role is to accept the electrons at the end of the chain, which is why we breathe.

Mitochondria also help regulate calcium levels inside the cell, and they are central to the controlled cell death by which the body removes cells it no longer needs.

Isolated from cultured mesenchymal stem cells derived from umbilical cord tissue, and supplied with the exosomes and secretomes from that culture. Supplied by mitochondrial count.