The Vital Force:
Proton Power and the Origins of Life
An Introduction to the topic,
From Lane, Nick.
Power, Sex, Suicide:
Mitochondria and the Meaning of Life
Oxford University Press, Oxford.
Excerpts from Part 2:
The Vital Force:
and the Origins of Life, pages 66-93.
“Energy and life go hand in hand.
If you stop breathing, you will not be able to generate the
energy you need for staying alive and you’ll be dead in a few minutes.
oxygen in your breath is being transported to virtually every one of the 15 trillion cells in your
body, where it is used to burn glucose in cellular respiration.
You are a fantastically energetic
Gram per gram, even when sitting comfortably, you are converting 10 000 times more
This sounds improbable, to put it mildly, so let’s consider the numbers.
The sun’s luminosity is
about 4 x 10
watts and its total mass is 2 x 10
Over its projected lifetime, about 10 billion
years, each gram of solar material will produce about 60 million kilojoules of energy.
generation of this energy is not explosive, however, but slow and steady, providing a uniform and
long-lived rate of energy production.
At any one moment, only a small proportion of the sun’s
vast mass is involved in nuclear fusions, and these reactions take place only in the dense core.
This is why the sun can burn for so long.
If you divide the luminosity of the sun by its mass, each
gram of solar mass yields about 0.0002 milliwatts of energy, which is 0.0000002 joules of energy
per gram per second (0.2
Now let’s assume that you weight 70 kg, and if you are
anything like me you will eat about 12 600 kilojoules (about 3000 calories [sic]) per day.
Converting this amount of energy (into heat or work or fat deposits) averages 2 millijoules per
gram per second (2 mJ/g/sec) or about 2 milliwatts per gram – a factor of 10 000 greater than the
Some energetic bacteria, such as
, generate as much as 10 joules per gram per
second, outperforming the sun by a factor of 50 million.
At the microscopic level of cells, all life is animated, even the apparently sessile plants, fungi, and
Cells whirr along, machine-like in the way that they channel energy into particular
tasks, whether these are locomotion, replication, constructing cellular materials, or pumping
molecules in and out of the cell.
Like machines, cells are full of moving parts, and to move they
. . .
[Peter Mitchell] put forward a radical new hypothesis in
in 1961 . . . He proposed that
respiration in cells worked by
, by which term he meant a chemical
reaction that could drive an osmotic gradient, or vice versa.
is a familiar term from
schooldays, even if we can’t quite remember what it means.
It usually means the flow of water
across a membrane from a less concentrated to a more concentrated solution, but Mitchell,
characteristically, didn’t mean it in that sense at all.
By ‘chemiosmosis’ we might imagine that he