Editing Pancake sorting (section)

===The burnt pancake problem===
In a variation called the '''burnt pancake problem''', the bottom of each pancake in the pile is burnt, and the sort must be completed with the burnt side of every pancake down. It is a ''signed permutation'', and if a pancake ''i'' is "burnt side up" a negative element ''i`'' is put in place of ''i'' in the permutation. In 2008, a group of undergraduates built a [[DNA computing|bacterial computer]] that can solve a simple example of the burnt pancake problem by programming ''[[Escherichia coli|E. coli]]'' to flip segments of DNA which are analogous to burnt pancakes. DNA has an orientation (5' and 3') and an order (promoter before coding). Even though the processing power expressed by DNA flips is low, the high number of bacteria in a culture provides a large [[parallel computing]] platform. The bacteria report when they have solved the problem by becoming antibiotic resistant.<ref>{{Cite journal|doi=10.1186/1754-1611-2-8|title=Engineering bacteria to solve the Burnt Pancake Problem|year=2008|last1=Haynes|first1=Karmella A|last2=Broderick|first2=Marian L|last3=Brown|first3=Adam D|last4=Butner|first4=Trevor L|last5=Dickson|first5=James O|last6=Harden|first6=W Lance|last7=Heard|first7=Lane H|last8=Jessen|first8=Eric L|last9=Malloy|first9=Kelly J|journal=Journal of Biological Engineering|volume=2|pages=8|pmid=18492232|pmc=2427008|last10=Ogden|first10=Brad J|last11=Rosemond|first11=Sabriya|last12=Simpson|first12=Samantha|last13=Zwack|first13=Erin|last14=Campbell|first14=A Malcolm|last15=Eckdahl|first15=Todd T|last16=Heyer|first16=Laurie J|author16-link= Laurie Heyer |last17=Poet|first17=Jeffrey L |doi-access=free }}</ref>