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Molecular Machines
Molecular Machines in Detail
by Dr Suzanne Ruddy, Principle Teaching Fellow UCL
About Suzanne Ruddy
My first career aspirations were to be a professional tennis player or a tourist, but there weren’t many opportunities for tennis and Easyjet had still to colonise the skies when I was growing up. Fortunately, as a teenager, I experienced the satisfaction of scientific exploration and realised that science gave me a way to ask interesting questions about life and attempt to answer them. I studied for both my BSc and PhD at Queen’s University Belfast before moving to England to undertake my research career. Even if I had made it as a tennis player, I would have ended up in the same role that I now occupy - that of teaching the next generation of participants. As a senior teaching fellow, I explain some the molecular mechanisms of life to undergraduates, and hope to inspire in my students the same curiosity and awe that perseveres.
Tiny machines a million times smaller than a millmetre (nanometres) are busy working inside the cells of your body right now. They enact the transfer of information from the genetic blueprint (DNA) to a working copy (RNA) to create the workforce of the cell - proteins. Proteins drive the processes of life and make up much of the cellular architecture. This information transfer is known as the central dogma, which states that the information contained in DNA is transferred to RNA by transcription, and this in turn is made into protein by the process of translation. All of this and more is carried out by tiny molecular machines. We probably have lots more molecular machines to discover, but here are a few facts that we know already:
1. The Replisome
The replisome replicates DNA when the cell is dividing to make sure that each daughter cell receives a faithful copy of the parent DNA.
2. Transcription Machinary
Transcription machinery reads the secure DNA code and makes multiple working copies of the gene on demand.
3. The Ribosome
The ribosome is a kind of translating machine that reads the genetic code of the RNA and turns it into the cellular workforce and building blocks of the cell - in other words, the proteins.
4. The Spliceosome
The spliceosome is a machine that chops up and reassembles the RNA in different combinations so that different proteins can be made from one original RNA. This is called alternative splicing and when it goes wrong, can result in disease.
5. Dynein
Dynein is the Royal Mail of the cell. It walks along paths (microtubules) carrying packages of proteins delivering these to where they are needed, with destinations encoded by address labels in each protein.
6. ATP Synthase
ATP synthase makes the ATP for the cell so that there is a constantly available energy supply to carry out all of the synthetic, mechanical and enzymatic processes in the cell
Understanding these molecular machines is really important to understanding the cell and working out the roots of many diseases such as cancer, neurodegenerative disease, genetic disease and even infectious disease. Are the machines going awry and making the wrong product, or too much or too little of it? Why? Can we adapt and use these machines as nanobots to solve problems and deliver drugs, to treat or cure disease, for example?
Further Reading
Kay E.R. and Leigh D.A. (2015) " Rise of the Molecular Machines" Wiley online library open access
Further Videos
Speaking of Chemistry The Nobel Prize in Chemistry: Molecular Machines explained
Your Body's Molecular Machines