Dresden 2011 – scientific programme

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BP: Fachverband Biologische Physik

BP 9: Posters: DNA \& DNA Enzymes

BP 9.5: Poster

Monday, March 14, 2011, 17:15–20:00, P3

A Probabilistic Polymer Model for Mitotic Chromosomes — •Yang Zhang and Dieter W. Heermann — Institute for Theoretical Physics, Heidelberg University, Heidelberg, Germany

Despite many years of extensive studies the structure of the mitotic chromosome still remains unclear. The present work introduces a new probabilistic polymer model for mitotic chromosomes. The key assumption of the model is the ability of the chromatin fibre to crosslink to itself due to the dyanmic binding of proteins to the fiber. These protein-chromatin interactions were included by a probabilistic and dynamic mechanism. This is motivated by the observation of high repulsive forces between ring polymers. Computer simulations were performed to examine the validity of the model. Our results show that the presence of loops leads to a tight compaction and contributes significantly to the bending rigidity of chromosomes. Moreover, its qualitative prediction of the force elongation behaviour are close to experimental findings. The dynamic loop model indicates the crucial role of loops in mitotic chromosomes and a strong influence of their number and size on the mechanical properties. This shows that changes of these mechanical characteristics under different conditions can be explained by an altered loop structure.