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MIT Making Computer Parts from DNA
Rei writes "Following in the footsteps of Lynn Conway's pioneering work on VLSI that allowed ordinary students to create their own processors, a group of MIT professors have almost completed doing the same thing
using DNA, known as synthetic biology. While not all of the components of a basic computer are working yet, there is hope that some day ordinary students may be able to design living computers, producing everything from novel drugs to seeds that sprout into treehouses."
Their approach is pretty cool, where the activity of each gene corresponds to one bit (actually one analog "voltage", but I digress) that can be independently controlled. Unfortunately each cell in their "computer" is expected to behave similarly, so the approach won't scale. The problem is that each gene is gonna be at least 1000 base pairs, roughly. Compare that to a typical bacterial genome (~5,000,000 base pairs) or the human genome (~3,000,000,000 base pairs), keeping in mind that large portions of those genomes are there to, well, keep the organism alive. Right now they're not even talking about taking over whole entire genomes here, just plasmids and viruses. That'll get you in the ballpark of 100,000 base pairs, or 100 bits, at most. Oh yeah, for each transition in a circuit here you'll have to make a new batch of proteins. That'll take minutes to hours. Not exactly stellar clock speeds. Which of course begs the question of how nature gets anything done at all. It's still pretty mysterious actually, but part of it comes down to the fact that your cells use feedback in a much more nuanced way than just "on" and "off". There's also lots of parts re-use, but probably the most important thing of all is communication and coordination *between* your cells. Like the fact that each neuron in your head does something different, and all of them put together make up something interesting and useful (hopefully). Rudimentary cell-cell communication circuits are already being constructed, and I'd like to see these scientists incorporate some of that into their work.