Mitochondria

In my last blog I talked a bit about mitochondria, and now they’re really in the news with the vote in the British House of Commons (equal to the US House of Representatives) to allow the use of another woman’s mitochondria when the intended mother’s mitochondria are in some way compromised leading to fatal disease in any child.

Of course we can expect to hear religious conservatives prattling on about meddling with God’s work. But even the press are using the term ‘a baby from three parents’.  Nonsense!

Dr Lynn Margulis, who until her death in 2011 was a professor at the University of Massachusetts at Amherst, was the pioneer of our understanding that in the early evolution of more complex forms of life certain bacteria got swallowed up into larger cells in what is now known and accepted as an extreme case of symbiosis: mitochondria as our energy ‘batteries’; and in plants chloroplasts for photosynthesis. These are microscopic organelles that have no say about me being a human as opposed to being a frog. And If you inject some chloroplasts from an oak tree into a rose bush it’s not then going to grow 80 feet tall and produce acorns! This British baby will be the child of its two parents’ gametes, just as I am.

Thanks to TV crime shows everyone has heard of DNA – deoxyribonucleic acid, a long thread like molecule that carries in the arrangement of it’s components the ability to make proteins. In the case of mitochondria there are a handful of genes specifically for making sugar metabolizing enzymes. With chloroplasts the little bit of DNA there controls the fabulous process of photosynthesis. But my mitochondria have had no say in making me a human being.  That happened when the nuclear DNA in the sperm from my father united with the nucleus in my mother’s egg cell. There’s no room for any mitochondria in the head of a sperm and so we get all our mitochondria from our mothers.

In 2002, Dr. Bryan Sykes of Oxford University published The Seven Daughters of Eve about the seven maternal lines of mitochondria amongst Europeans. Just seven. So in this British case, it will be pretty easy to find a donor with the exact same mitochondria as the mother.

We’re all happy to accept someone else’s blood when needed, provided it’s the same blood type of course. Same with mitochondria.  No genetic change, no ‘third parent’.  

Red blood cells carry oxygen to our cells. Once there the mitochondria use that oxygen to burn glucose to make energy - two organelles working in close cooperation. Let’s focus on the miracle of a new healthy baby made possible by these advances in medical science.