Synthetic Biology Creates Living Computers

Most people have at least a fuzzy idea of what DNA is. Ask about RNA, though, and unless you are talking to a biologist, you are likely to get even more handwaving. We hackers might have to reread our biology text books, though, since researchers have built logic gates using RNA.

Sometimes we read these university press releases and realize that the result isn’t very practical. But in this case, the Arizona State University study shows how AND, OR, and NOT gates are possible and shows practical applications with four-input AND gates and six-input OR gates using living cells. The key is a construct known as an RNA toehold switch (see video below). Although this was worked out in 2012, this recent study shows how to apply it practically.

In the cellular world (that’s biological cells, not mobile phone cells), the DNA is almost like a disk drive–it contains information about what to do. RNA has a similar chemical structure, but–unlike DNA–is usually single-stranded. It can copy segments of the DNA using a transcription process. This messenger RNA can then fold into a complex three-dimensional shape since it isn’t bound to a second strand. Ribosomes can read this RNA and stitch together amino acids to form proteins that actually do the work in the cell.

We aren’t pros on biology, but you could make the case that DNA is like mass storage for a program, RNA is the RAM memory, and the ribosomes are the CPU and 3D printer of the whole setup. RNA is also used to move raw material to the ribosomes, much as RAM memory can hold instructions and data. And just as CPU itself usually contains memory in the form of registers, the components that make up a ribosome are proteins and RNA. We aren’t biologists, so take that analogy with a grain of salt.

Because of the tiny size of cells and the way RNA-based computing works, it offers the opportunity for major parallelism, similar to quantum computing. In addition, because this can affect living cells, researchers think it will lead to new types of smart drugs and better medical diagnostic tools. A similar technique from the same team has already demonstrated it can detect the Zika virus.

The next step is to create neural networks inside cells and the formation of a cell network (again, not the telephone kind) allowing processing elements in one cell to talk to another. We have the Internet of things. Perhaps one day we’ll have the Internet of cells.

If you are into the biology hacking, we’ve talked about using RNA transcription as a means of stopping infections. If you want to know a lot more about how to synthesize oligonucleotides (fancy talk for DNA and RNA), we looked at how to make them in space.