Telomeres, non-coding terminal structures of DNA strands, consist of repetitive long tandem repeats of a specific length. An absence of an enzyme, telomerase, in certain cellular structures requires an alternative telomerase-independent pathway for telomeric sequence length regulation. Besides linear telomeres other configurations such as telomeric circles and telomeric loops were experimentally observed. They are suspected to play an important role in a universal mechanism for stabilization of the ends of linear DNA that possibly dates back to pre-telomerase ages. We propose a mathematical model that captures biophysical interactions of various telomeric structures on a short time scale and that is able to reproduce experimental measurements in mtDNA of yeast. Moreover, the model opens up a couple of interesting mathematical problems such as validity of a quasi-steady state approximation and dynamic properties of discrete coagulation-fragmentation systems. We also identify and estimate key factors influencing the length distribution of telomeric circles, loops and strand invasions using numerical simulations.
