- DNA transport through membranes is a key step in many biological processes. The phenomenon of DNA penetration through narrow polymer membrane pores was previously observed only under the influence of external electric fields. Recently, it was shown that some types of DNA could penetrate through membrane pores also under hydrodynamic pressure. Here we show that double-stranded plasmid DNA with a 350 nm hydrodynamic diameter penetrates through membrane pores as narrow as 10 nm under pressure, and suggest that the supercoiled plasmids penetrate through these narrow pores by stretching into long hair-shaped flexible strands. We study the kinetics of plasmid penetration and the changes in plasmid elasticity caused by UV irradiation. The results suggest a mechanism based on “snake-like” movement with gradual pore blocking.Graphical abstractView high quality image (240K)Research highlights► The supercoiled double-stranded 350 nm DNA penetrates through 10 nm pores. ► The plasmids penetrate by stretching into long hair-shaped flexible macromolecules. ► A critical pressure has to be exerted by the flow in order to stretch the plasmid. ► A “snake-like” movement with gradual pore blocking is suggested. ► The results shed light on the mechanisms of virus transport and cell penetration.