What do our cells and hydroelectric power stations have in common?

If you go to Dinorwig, a small village in North West Wales, you will see an incredible feat of engineering. Below Elidir mountain, 16km of tunnels¹ make up a hydroelectric power station with an approximate output of 1,728 megawatts². How is this electricity generated?

A dam is used to store water in Marchlyn Mawr reservoir; the underground tunnels allow water to flow downhill into Llyn Peris reservoir, turning a turbine which generates the electricity in doing so. But Dinorwig power station is not just any old HEP station: it uses pumped storage, a method where off-peak, cheaper electricity is used to pump water back up from Llyn Peris back up to Marchlyn Mawr, so that it can be reused³.

Dinorwig power station is one of only two pumped-storage hydroelectric power stations in the UK (the other one is in Ffestiniog, also in North West Wales). But a very similar system exists at all times in the cells of every single living organism: chemiosmosis.

When we respire, we break down glucose in the presence of oxygen to release energy, which can then be used to drive processes in our cells. This actually takes place in a large series of chemical reactions which occur in the mitochondria (the “batteries” of living cells). In the final step of this process, electrons are passed through a series of protein complexes, releasing bursts of energy that can be used to pump hydrogen ions from the interior of the mitochondria to the space between its two membranes. In this stage, the ions are being pumped from a lower to a higher concentration (naturally they would move from higher to lower without the input of energy). This is analogous to the pumping of water from the lower reservoir to the higher reservoir, using energy to drive the water against the force of gravity.

The hydrogen ions in what is known as the intermembrane space now have potential energy in the form of a concentration and charge gradient. Our cells can make use of this energy: as the ions flow passively back from the intermembrane space into the interior of the mitochondria, the energy from their movement is used to produce a molecule called ATP, the energy currency of our cells.

To me, chemiosmosis is just one illustrator of the fantastic machinery of our cells and bodies. It never ceases to amaze and dumbfound me how complex even the most primitive of organisms are, and how evolution by natural selection has shaped the biological processes that occur within our cells all the time without us even thinking about them. I hope you find this as interesting as I do, and if you didn't already know about the chemiosmotic mechanism, then perhaps you've learnt something new.

I haven’t decided what my next blog post will be about, but it could be on either eusocial behaviour or the biological significance of water. If you’re reading this, I would really love feedback and ideas, just so I know that I’m reaching people! Thanks a lot.

References:

1.       http://www.fhc.co.uk/dinorwig.htm

2.       http://en.wikipedia.org/wiki/Dinorwig_Power_Station

3.       http://water.usgs.gov/edu/hyhowworks.html

4.       http://www.fhc.co.uk/images/pics/dinorwig1.jpg

5.       http://84d1f3.medialib.glogster.com/media/d6/d613b845a769d565f901820c957de1a0bd2b2acf866f291d636a3e60fb648295/co-jpg.jpg

Biomaterials: applying materials science to living organisms

So, I decided to focus my first proper post on biomaterials. Biomaterials science – there’s a field which unites the three sciences if I ever saw one. Materials science hovers delicately on the border between Chemistry and Physics, and here materials are exploited for use in living organisms, with obvious medical applications.

Biomaterials science first grabbed my attention when I was at a materials summer school at Manchester University, and there was a research talk on it which really interested me. I find it fascinating that scientists can engineer materials that can be used to improve the way our bodies work in some fashion. And the applications are so diverse: from the tiny buckminsterfullerene (buckyballs) which can be used in drug delivery, to the design of prosthetic limbs¹ – the possibilities are enormous.

   A carbon buckyball can transport drugs 
         to particular cells in the body²

An important type of biomaterial is nanoparticles – substances which are less than one ten-thousandth of a millimetre in length or thickness. Being so tiny, nanoparticles can enter our cells and move through blood vessels. A particular application of this that I’ve been reading about is gold particles in biomedicine.

One use of these gold particles is in chemical delivery systems: the nanoparticles are bound to or coated with a substance that you want to introduce into the cell (such as a particular protein)³. They are then “engulfed” by the cell: the membrane of the cell pinches in and fuses around the gold particles, a process called endocytosis. The substances attached to the gold particles are targeted at a particular part of the cell, such as the nucleus (the information-containing centre of a cell), but doing so has proven difficult because after the particles have been taken into the cell, they are often stuck inside the bit of membrane which originally engulfed them (known as the endosome)³. This is a big problem!

There are many other diverse applications of biomaterials which are rapidly growing, such as tissue engineering (where body tissues are regenerated or enhanced using cell exploitation techniques)⁴. I hope my rather superficial overview of what biomaterials is about has interested you as a reader and perhaps inspired you to learn more.

I’ll end my first post here; look out for my next one which *might* be on the chemiosmotic principle. Thanks for reading!

1.       http://science.howstuffworks.com/prosthetic-limb.htm

2.       Picture: http://www.animalnewyork.com/2012/la-dolche-vita-rats-fed-carbon-buckyballs-in-olive-oil-live-twice-as-long/

3.       The Biochemist, Vol 35. No 1. Gold Nanoparticles in Biomedicine by Catherine Berry

4.        http://www.tissue-engineering.net/index.php?seite=whatiste