The Jackprot Simulation Couples Mutation Rate with Natural Selection to Illustrate How Protein Evolution Is Not Random

The Jackprot is a didactic slot machine simulation that illustrates how mutation rate coupled with natural selection can interact to generate highly specialized proteins. Conceptualized by Guillermo Paz-y-Miño C., Avelina Espinosa, and Chunyan Y. Bai (New England Center for the Public Understanding of Science, Roger Williams University and the University of Massachusetts, Dartmouth), the Jackprot uses simplified slot-machine probability principles to demonstrate how mutation rate coupled with natural selection suffice to explain the origin and evolution of highly specialized proteins. The Jackprot also helps us understand why evolution by means of natural selection cannot be a random process. Winning the ‘jackprot,’ or highest-fitness complete-peptide sequence, requires gradual and cumulative smaller ‘wins’ (rewarded by selection) at the first, second and third nucleotide positions in each of the codons coding for a polypeptide (= ‘jackdons’ that lead to ‘jackacids’ that lead to the ‘jackprot’). A slot-machine represents the cellular chemical apparatus, product itself of Darwinian evolution, required to generate, step by step, each of the three nucleotides coding for an amino acid. The probability of getting the correct triplet, for example, the start codon methionine or ATG, in a single attempt (or winning the ‘jackacid’), is equal to 1/64, or one divided by 4 x 4 x 4 (i.e. the total number of possible nucleotides per position multiplied by itself three times)… …But because molecular evolution occurs gradually, a naturalistic assumption of the ‘jackprot’ model, each time any of the correct nucleotides is generated by the slot-machine, natural selection rewards it and keeps it (partial nucleotide win in a codon or ‘jackdon’)… …Therefore, the probability of arriving, nucleotide by nucleotide, at the ATG sequence is equal to 1/12, or one divided by 4 + 4 + 4 (i.e. the summation of the individual probabilities for each nucleotide position), a much faster evolutionary process. Note that the sequential and additive arrival at the phenotypically meaningful sequence of A plus T plus G, represents, in reality, the accumulation of events fixed by natural selection during protein evolution, which entails clustered changes of multiple parts, and at diverse locations, within functional protein domains. The article includes links to the simulation program (http://faculty.rwu.edu/cbai/JackprotSimulation.htm), a simulation guide for teachers and educators (http://faculty.rwu.edu/aespinosa/aespinosa/Outreach_files/The_Jackprot_Simulation_Guidelines-1.pdf), a video prepared by college students and three attachments)

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