Stretching single stranded DNA

Recently, single molecule force spectroscopy experiments provided much important information about the elastic properties of a single stranded DNA. Theoretical efforts, which followed these experiments could not provide satisfactory explanation for some of the observed results. For example, a decrease in the extension with temperature at high force, multi step transition in the force extension curve of poly(dA), etc. need further attention. In this brief review, we discuss a few of these experiments and illustrate that lattice models developed in the framework of statistical mechanics may describe some of the observed features. We also propose an experimental protocol, which may enable us to observe re-entrance, a long standing issue related to the force induced transitions of biopolymers.