# Transcriptor

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{{For|the first step in gene expression|Transcription (genetics)}}

A '''transcriptor''' is a [transistor](/source/transistor)-like device composed of [DNA](/source/DNA) and [RNA](/source/RNA) rather than a [semiconducting material](/source/semiconducting_material) such as [silicon](/source/silicon).  Prior to its invention in 2013, the transcriptor was considered an important component to build [biological computers](/source/biocomputer).<ref name=Extreme />

==Background==
To function, a modern [computer](/source/computer) needs three different capabilities:  It must be able to [store information](/source/data_storage_device), transmit information between components, and possess a basic [system of logic](/source/logic_family).<ref name=IO9 />  Prior to March 2013, scientists had successfully demonstrated the ability to store and transmit data using biological components made of proteins and [DNA](/source/DNA).<ref name=IO9>{{cite news|title=This new discovery will finally allow us to build biological computers|author=Robert T. Gonzalez|work=IO9|date=March 29, 2013|url=http://io9.com/this-new-discovery-will-finally-allow-us-to-build-biolo-462867996|accessdate=March 29, 2013}}</ref>  Simple two-terminal [logic gate](/source/logic_gate)s had been demonstrated, but required multiple layers of inputs and thus were impractical due to scaling difficulties.<ref name=paper>{{cite journal|title=Amplifying Genetic Logic Gates|author=Jerome Bonnet|author2=Peter Yin|author3=Monica E. Ortiz|author4=Pakpoom Subsoontorn|author5=Drew Endy|journal=Science|date=March 28, 2013|doi= 10.1126/science.1232758|pmid=23539178|volume=340|issue=6132|pages=599–603|bibcode=2013Sci...340..599B|s2cid=206546590}}</ref>

==Invention and description==
On March 28, 2013, a team of [bioengineer](/source/bioengineer)s from [Stanford University](/source/Stanford_University) led by [Drew Endy](/source/Drew_Endy) announced that they had created the biological equivalent of a transistor, which they named a "transcriptor".  That is, they created a three-terminal device with a logic system that can control other components.<ref name=IO9 /><ref name=paper />  The transcriptor regulates the flow of [RNA polymerase](/source/RNA_polymerase) across a strand of DNA using special combinations of enzymes to control movement.<ref name=Extreme>{{cite news|title=Stanford creates biological transistors, the final step towards computers inside living cells|author=Sebastein Anthony|date=March 29, 2013|work=Extreme Tech|url=http://www.extremetech.com/extreme/152074-stanford-creates-biological-transistors-the-final-step-towards-computers-inside-living-cells|accessdate=March 29, 2013}}</ref> According to project member Jerome Bonnet, "The choice of enzymes is important. We have been careful to select enzymes that function in bacteria, fungi, plants and animals, so that bio-computers can be engineered within a variety of organisms."<ref name=Extreme /> 

Transcriptors can replicate traditional [AND](/source/AND_gate), [OR](/source/OR_gate), [NOR](/source/NOR_gate), [NAND](/source/NAND_gate), [XOR](/source/XOR_gate), and [XNOR gate](/source/XNOR_gate)s with equivalents, which Endy dubbed "Boolean Integrase Logic (BIL) gates", in a single-layer process (i.e., without requiring multiple instances of the simpler gates to build up more complex ones).<ref name=IO9 /><ref name=paper /> Like a traditional transistor, a transcriptor can amplify an input signal.<ref name=Extreme />  A group of transcriptors can do almost any type of computing, including counting and comparison.<ref name=IO9 /><ref name=SJMN />

==Impact==
Stanford dedicated the BIL gate's design to the [public domain](/source/public_domain), which may speed its adoption.<ref name=Extreme />  According to Endy, other researchers were already using the gates to reprogram [metabolism](/source/metabolism) when the Stanford team published its research.<ref name=SJMN />

Computing by transcriptor is still very slow; it can take a few hours between receiving an input signal and generating an output.<ref>{{cite news|title=How to Make a Computer From a Living Cell|author=Katherine Bourzac|work=MIT Technology Review|publisher=Mashable|date=March 28, 2013|url=http://mashable.com/2013/03/28/computer-from-living-cell/|accessdate=March 30, 2013}}</ref> Endy doubted that biocomputers would ever be as fast as traditional computers, but added that is not the goal of his research.  "We're building computers that will operate in a place where your cellphone isn't going to work", he said.<ref name=IO9 />  Medical devices with built-in biological computers could monitor, or even alter, cell behavior from inside a patient's body.<ref name=Extreme />  ''[ExtremeTech](/source/ExtremeTech)'' writes:
{{quote|Moving forward, though, the potential for real biological computers is immense. We are essentially talking about {{Sic|hide=y|fully|-}}functional computers that can sense their surroundings, and then manipulate their host cells into doing just about anything. Biological computers might be used as an early-warning system for disease, or simply as a diagnostic tool&nbsp;... Biological computers could tell their host cells to stop producing insulin, to pump out more adrenaline, to reproduce some healthy cells to combat disease, or to stop reproducing if cancer is detected. Biological computers will probably obviate the use of many pharmaceutical drugs.<ref name=Extreme />}}

[UC Berkeley](/source/University_of_California%2C_Berkeley) biochemical engineer [Jay Keasling](/source/Jay_Keasling) said the transcriptor "clearly demonstrates the power of synthetic biology and could revolutionize how we compute in the future".<ref name=SJMN>{{cite news|title=Biological computer created at Stanford|work=San Jose Mercury News|date=March 29, 2013|author=Lisa M. Krieger|url=http://www.mercurynews.com/business/ci_22898974/biological-computer-created-at-stanford|accessdate=March 29, 2013}}</ref>

==References==
{{reflist|30em}}

==External links==
*{{cite journal|title=Amplifying Genetic Logic Gates|author=Jerome Bonnet|author2=Peter Yin|author3=Monica E. Ortiz|author4=Pakpoom Subsoontorn|author5=Drew Endy|journal=Science|date=March 28, 2013|doi= 10.1126/science.1232758|pmid=23539178|volume=340|issue=6132|pages=599–603|bibcode=2013Sci...340..599B|s2cid=206546590}} - original journal article, published in ''[Science](/source/Science_(journal))'' 
*[https://www.youtube.com/watch?v=ahYZBeP_r5U Explanatory video] created by Drew Endy 
*[https://www.npr.org/2013/03/29/175604770/tiny-dna-switches-aim-to-revolutionize-cellular-computing NPR article] with series of moving pictures that explain how the transcriptor works
*[https://biobricks.org/bpa/contributions/57/ Public domain release] of the BIL gates technology

Category:American inventions
Category:DNA nanotechnology
Category:Molecular biology
Category:Theoretical computer science

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Adapted from the Wikipedia article [Transcriptor](https://en.wikipedia.org/wiki/Transcriptor) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Transcriptor?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.