The theme of the paper is the relationship between gesture and argumentation structure and semantic content. An analysis is given of the relationship between speech and gesture that occurs in a video-recorded discussion among students of chemical biology and their supervisor where they are asked to describe what they experienced during a haptic laboratory exercise in protein ligand docking. The analysis focuses especially on the repeated use of speech together with gesture expressions, the repetition of gestures by the same and different speakers, sequences and transformations of gestures, the change in function of a gesture, and interactive gesturing.