Examples of Turing Machines: Loops, Halts, and Rewriting

The Most Recent Implementation of a Turing Machine

Animated DNA image by brian0918

Animated DNA: Image by brian0918

As of February 2012, the most recently devised Turing machine is also the most unusual physical implementation.

Professor Ehud Keinan created a Turing machine using snippets of DNA. This biological TM decodes images that had been encoded using DNA attached to a chip.

Alan Turing (1912-1954) might have been especially pleased at a biological implementation of a Turing machine. He had speculated that repeated patterns in biology, such as a tiger’s stripes, are caused by the paired action of an activator agent and an inhibitor agent. Researchers at King’s College (Turing’s alma mater) recently reported finding the first experimental evidence of such an activation-inhibition pair, in the ridges of a mouse’s upper palate.


Economou, A., Ohazama, A., Porntaveetus, T., Sharpe, P., Kondo, S., Basson, M., Gritli-Linde, A., Cobourne M., Green, J. Periodic stripe formation by a Turing mechanism operating at growth zones in the mammalian palate. (2012). Nature Genetics. Accessed February 24, 2012.

Barker-Plummer, D. Turing Machines. The Stanford Encyclopedia of Philosophy (Spring 2011 Edition), Edward N. Zalta (ed.). Accessed February 24, 2012.

Shoshani, S., Piran, R., Arava, Y., Keinan, E. A Molecular Cryptosystem for Images by DNA Computing. (2012). Angewandte Chemie. Accessed February 24, 2012.

Weisstein, E. W. Turing Machine. MathWorld–A Wolfram Web Resource. (1999-2012). Accessed February 24, 2012.

Click to Return to Page One: Examples of Turing Machines

© Copyright 2012 Mike DeHaan, All rights Reserved. Written For: Decoded Science
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