Tuesday, 27 January 2015

Natural technology: the bacterium

image credit: https://ufhealth.org/anaerobic-bacteria

The simplest form of life – a single-celled organism such as a bacterium – is made up of 10 million million atoms. Cells within the human body are at least comparable in structure. They form a system immeasurably more complex than anything artificial, comprising a hierarchy of integrated subsystems and architectures using thousands of different proteins, their actions orchestrated in some inexplicable manner.

In his book The Way of the Cell (Oxford University Press, 2001,  p.329) Franklin M. Harold compares it to a high tech factory comprising

  • Control mechanisms regulating the automated assembly of parts and components

  • Software languages and their decoding systems

  • Memory banks for  information storage and retrieval

  • Quality control systems with error fail-safe and proof-reading

  • Assembly processes involving prefabrication and modular construction

Each one of these functions requires intelligence, decision-making and information exchange to an extraordinary degree and the whole organism responds and adapts to the external environment in a purposeful way. Moreover, the entire mobile factory has the ability to self-replicate in a few hours.

A bacterium is an example of a single-celled organism. To get a better idea of the scale of the engineering task solved by nature consider just one part of a bacterium: the propulsion unit. This is a microscopic propeller for driving the bacterium through a fluid. The propeller takes the form of a whip made of a protein called flagellin, which is why the whole propulsion unit is called a flagellum.  

The flagellum is about 2 microns in length and is powered by a motor only 1/5th this size. It can spin at 10,000 r.p.m. and stop the spin in only one quarter of a revolution and instantly start spinning in the opposite direction. Connecting the flagellum to the drive shaft is a hook protein which acts as a universal joint which allows the propeller and drive shaft to rotate freely. The drive shaft penetrates the wall of the bacterium with the aid of a bushing material comprising several types of protein and connects with a rotary engine which gets its energy from the flow of acid through a membrane, itself a complex process yet to be understood. Altogether, the flagellum comprises over thirty different proteins. (This is based on an interview with M.J.Behe reported in a book called The Case for a Creator by Lee Strobel.)

If any one part were missing the whole power unit would not work and each subunit would be useless unless connected into the whole system. A bacterium or any single cell is packed full of complex subsystems like this and they all have to be integrated and choreographed for the bacterium to work.

 Bacteria are incomprehensibly numerous (not surprisingly, given that most of the natural world is incomprehensible in the way it is organised and interrelated). Each person has 10 times as many  bacterium cells as cells in the body-brain system, i.e. 100 trillion vs a mere 10 trillion. They reside mainly in the gut and skin. On the planet as a whole their biomass exceeds that of all the plants and animals put together. The total number is estimated at 5 x 10power30 (5 followed by 30 zeros). Placed end to end they would stretch thousands of millions of light years into space. This may seem difficult to believe - but check with a mathematically inclined friend  or do the calculation yourself.  Let me know if he or she gets a different answer!

What I had not realised until recently is the extraordinary efficiency of the DNA base-pair coding to achieve such a complexity of functions. It does not seem to have much to do with the amount of the coding. The simplest forms of life sometimes have more DNA than a  human being. Evolution  is about creativity and efficient problem solving using minimum resources. Competition between life forms for resources is a factor, but only a factor. In order to compete a biological entity must first be viable.

 Bacteria were around very early on in the history of our planet –  some  5% of the the way through its 4.3 billion years. So the facile answer that it was evolution 'what did it' won’t wash (i.e. the 'evolution of the gaps' argument, by analogy with the 'god of the gaps'). I believe there is evolution and has been since the universe began – but that’s a description, not a causative mechanism. I picture it as the Creator, who is outside space-time, painting a work of art, experimenting creatively, intelligently, as the cosmic masterpiece unfolds, with each atom, star and organism falling into a tapestry. To us it looks like a progressive sequence of events.

Regardless of their recognition of the existence of a Creator I believe that some biophysicists are already looking into the possibility of intelligence entering our universe through quantum phenomena. If it proves to be the case it will be revolutionary indeed.

See also

Natural technology: the virus

The passive gene


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