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Contents 1 Half-adder or Full-adder 1.1 Idea: Pattern recognition 1.1.1 Main Goal: 1.1.2 Implementation from the ingenieur point of view 1.1.3 Implementation from the biologist point of view 1.1.4 Pro's & Con's

Half-adder or Full-adder

An implementation of a half-adder or full-adder: 1-bit adder with carry

• [http://en.wikipedia.org/wiki/Full_adder half/full adder in wikipedia]

Idea: Pattern recognition

→ Illustration of the concepts:

• slides (pdf, 352KB)
• handout (pdf, 268KB)

Main Goal:

1. Write something with a chemical on a petri plate (like ETH for example)
2. Let Bacteria grow uniformly on the plate
3. Expose the plate to a picture (black and white) of the same pattern
4. Result:
   • Bacteria gets green when pattern on the plate and picture match (light and chemical)
   • Bacteria does not express fluorescent protein when pattern on the plate and picture match (no light and no chemical)
   • Bacteria gets red when pattern on the plate and picture do not match

Implementation from the ingenieur point of view

• Half Adder
• = opportunity to build an AND and an XOR Gate

Implementation from the biologist point of view

• AND Gate: presence of chemical induces the production of an inactive protein, which is activated by a second protein (produced when light is present): the first protein is then activating GFP production
• XOR Gate: I think Marko had a good idea about that (I didn't really got it)
• a light sensible promoter (there are some, see [http://partsregistry.org/Featured_Parts:Light_Sensor here])
• a chemical sensible promoter (chemical to be defined)
• we would need to give a kind of first signal to the system (to don't have light reactions before a certain moment, otherwise we have to work in a dark room...), an activation signal after the bacterias have grown on the plate

Pro's & Con's

Pro's:

• meaningful from engineering point
• valuable parts for synthetic biology
• stepwise proceeding applicable (→ intermediate and partial results!)
• experiments visually attractive
• probably simple enough

Con's:

• cheap copy of “bio-film” project ([http://partsregistry.org/cgi/htdocs/SBC04/index.cgi iGEM 2004])
• sensational experiments, have little in common with half adder
• maybe that a big vision is lacking
• general/practical benefit? (counter-argument: is this required?)
• too simple?