In many cultures, surnames are passed from father to child.
I'm a McLysaght because my father, my father's father,
and my father's grandfather were McLysaghts.
Unfortunately, my many female ancestors don't get recorded.
And in fact, I don't even know my
great-grandmothers' maiden names.
But there does exist a very important genetic link between
the women in my family.
And that's found not on the 23 pairs of chromosomes that lie
within the cell nucleus.
Instead, it's found in another part of the cell called the
mitochondria.
So here it is.
This is a mitochondria.
And this is a component of cells of eukaryotes.
That's everything except bacteria.
They're sometimes known as the powerhouse of the cell.
And that's because they produce all the chemical
energy, known as ATP, that's required for metabolism.
But they do other things as well.
They're involved in signalling and in cell
growth and cell death.
But one really fascinating thing about mitochondria is
that they've got their own little circular genome that's
completely separate from the other chromosomes in the cell.
It's really very short.
It's about 15,000 times shorter than chromosome 1.
And it only contains 37 genes, 13 of which are involved in
the energy functions.
And in any one given cell, there are many mitochondria,
ranging from hundreds to hundreds of thousands.
But the really fascinating thing is how they got there in
the first place.
In 1966, a young biologist called Lynn Margulis noticed
similarities between mitochondria and free-living
microbes and proposed a theory on the origins of the
mitochondria.
She suggested that about one and a half billion years ago,
one bacteria was eaten by another cell and instead of
being digested, lived inside the other cell and formed a
mutually beneficial symbiotic relationship, eventually
becoming the mitochondria.
When Lynn Margulis first proposed this theory, she
wasn't believed.
And the idea failed to gain traction.
She showed remarkable tenacity, however.
And she stuck with it.
Eventually, her perseverance paid off.
And it was later shown that the mitochondrial DNA has
similarities to the DNA of free-living bacteria.
Her endosymbiotic theory was proven true.
It's disappointing to think that the reason why this idea
was slow to gain acceptance is the fact that it was
championed by a woman.
These days, however, it's no longer considered a crazy idea
and it's in every biology textbook.
But the mitochondrial DNA has also helped women be
remembered in another way.
And that's because of its special inheritance pattern.
And this is that the mitochondria are provided by
the egg cell but not the sperm.
And so, much like surnames are passed from father to child,
mitochondria are passed from mother to child.
And more than this, the mitochondrial DNA doesn't
undergo the same recombination as occurs to the other 23
chromosomes.
So your mitochondrial DNA was inherited intact from your
mother, who got it from her mother and so on.
And so this provides a record of the maternal line right
back to the origins of humans.
So to me, there is a certain poetry in the way that the
mitochondria links us to our female ancestors while at the
same time serves as an important reminder of the
challenges faced by women in science.