So the pentapeptide short protein component. Now the question is what exactly is the reaction by which the bacterial cells actually build these cross linkages in the first place? Well this is the reaction that is described on the board. So we have the pentapeptide, so let's say the pentaglycine. So this is glycine one, glycine two, glycine three, glycine four, and the terminal glycine that we basically drew out. Now it's the nitrogen of this pentaglyne.