A schematic of a Chlamydomonas cell (from transmission electron micrographs) showing the anterior flagella rooted in basal bodies, with intraflagellar transport (IFT) particle arrays between the axoneme and flagellar membrane, the basal cup-shaped chloroplast, central nucleus and other organelles. An expanded cross section of the flagellar axoneme, as redrawn from (48), shows the nine outer doublets and the central pair (9+2) microtubules; axoneme substructures are color-coded and labeled (see inset).