  We study the influence of some quenched disorder in the sequence of monomers
on the entropic elasticity of long polymeric chains. Starting from the
Kratky-Porod model, we show numerically that some randomness in the favoured
angles between successive segments induces a change in the elongation versus
force characteristics, and this change can be well described by a simple
renormalisation of the elastic constant. The effective coupling constant is
computed by an analytic study of the low force regime.
