A probabilistic model for the time to unravel a strand of DNA

R. J. Vanderbei, L. A. Shepp

Research output: Contribution to journalArticlepeer-review


A common model for the time σL (sec) taken by a DNA strand of length L (cm) to unravel is to assume that new points of unraveling occur along the strand as a Poisson process of rate λ 1/(cm x sec) in space-time and that the unraveling propagates at speed v/2 (cm/sec) in each direction until time σL. We solve the open problem to determine the distribution of σL by finding its Laplace transform and using it to show that as x = L2λ/v → ∞, σL is nearly a constant:σL= 1 λvlog L2λ v 1 2We also derive (modulo some small gaps) the more precise limiting asymptotic formula: for - ∞ < θ < ∞,PσL< 1 λvψ 1 2[log(L2 λ v)]+ θ ψ 1 2[log(L2 λ v)]→e-ewhere ψ is defined by the equation: ψ(x) = log ψ(x)+x, x≥1. These results are obtained by interchanging the role of space and time to uncover an underlying Markov process which can be studied in detail.

Original languageEnglish (US)
Pages (from-to)1177
Number of pages1
JournalMathematical and Computer Modelling
Issue number9
StatePublished - 1989
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Modeling and Simulation
  • Computer Science Applications


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