Figure: A. Light microscopic image of a Chlamydomonas cell with two flagella. B. 3D view of a ~2 μm long piece of a flagellum imaged by cryo-electron tomography. C-F. Comparison of the 3D flagellar structure from wild type (C, D) and an amiRNAi mutant (6E6), which is missing parts of the Calcium sensing complex, CSC (E, F). In wild type both radial spokes, RS1 (blue) and RS2 (yellow) are present, while in the mutant RS2 is frequently missing in the repeating building blocks. G. Graphical model showing presence and absence of radial spokes in the same mutant flagellum. [Images A, B modified from Heuser et al. (under review); images C-G modified from Dymek et al. 2011].