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DNA Computing. Herman G. Meyer III Sept. 28, 2004. Overview. DNA DNA/CPU Comparison Leonard M. Adleman Proof of Concept Experiment. DNA. Adenine, Thymine, Guanine, & Cytosine (A,T,C,G) Polymerase Watson-Crick Pairing (A-T,C-G) Cheap Compact Data Storage 1 cm^3 DNA = 10^12 CDs
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DNA Computing Herman G. Meyer III Sept. 28, 2004
Overview • DNA • DNA/CPU Comparison • Leonard M. Adleman • Proof of Concept Experiment
DNA • Adenine, Thymine, Guanine, & Cytosine (A,T,C,G) • Polymerase • Watson-Crick Pairing (A-T,C-G) • Cheap • Compact Data Storage • 1 cm^3 DNA = 10^12 CDs • Redundant
DNA/CPU Comparison • CPU • Sequential Operations • addition, bit-shifting, logical operations (AND, OR, NOT, NOR) • DNA • Parallel Operations • Cut, Copy, Paste, Repair
Leonard M. Adleman • Background in Mathematics & Computer Science • HIV Research • DNA/Turing Machine similar • Proof of Concept
Proof of Concept Experiment • Directed Hamiltonian Path • Pseudo code • Generate random paths • For each path • Check Start/End points • Check Length • Check that all vertices exist • If any path passes all tests, HP exists
Programming the DNA • Cities • Flights
Recipe • In a test tube add • 10^14 molecules of each city • 10^14 molecules of each flight • Water, ligase, salt • Answer generated in about one second • 100 trillion molecules representing wrong answers also generated
Ligases • Bind molecules together • Concatenates DNA strands
Polymerase • Copies DNA • Primers (Start, Complement of End) • PCR
Gel Electrophoresis • Sort molecules by length • Molecules have a charge • Magnets used
Checking Cities • Attach city complement to iron ball • Suspend ball in solution • Watson-Crick pairing attraction • Wrong answers poured out • Repeat for each city
Did it work? • DNA remaining in test tube encoded the valid Hamiltonian Path
Drawbacks • The process required much human intervention • Automation would be required for a “real” computer • Same method on 200 cities would require more than DNA than the mass of Earth
Thoughts • Could a DNA Computer get sick? • Virus • Cancer • Is it biodegradable? • Could a virus spread from computer to humans? • If so, could virus writers spread more deadly viruses? • New level of bioterrorism
Summary • DNA can be used for simple calculations • DNA is a compact form of data storage • DNA is exponentially parallel • DNA is redundant
References • Ars Technica. http://arstechnica.com/reviews/2q00/dna/dna-5.html • Scientific American - August 1998. pp 54-61 • Science - Vol. 266. Nov. 11, 1994. pp 1021-1024