Spatial representation of cellulose synthesis in the red algal cell wall N. OROLOGAS and I. TSEKOS Abstract Cytological observations on the red alga Erythrocladia subintegra, together with improved freeze-fracture studies using rotary and unidirectional shadowing, have led to the proposal of a membrane flow concept for the origin of terminal complexes (TCs). According to this concept, cellulose synthases (as zymogenic particles, or globules) are made in the endoplasmic reticulum, transferred to Golgi cisternae where they are activated, and transported via Golgi vesicles to the plasma membrane. In the plasma membrane, globules (consisting of more subunits) aggregate, swell and unfold, and become closely arranged contributing to TC assembly. 3D modeling is a powerful tool for better understanding and explaining cell structure and function, also useful for educational purposes. An attempt was made to represent the following in a simple 3D model: (1) formation, development and spatial distribution of the linear terminal complexes (TCs) of Erythrocladia cells, (2) cellulose microfibril secretion and assembly and (3) TCs cooperation in order to create the crystalline-phase network of the cell wall.   < back .