In our laboratory we study eukaryotic flagella and cilia, the principal organelles of cell motility, which are increasingly recognized as having critical signalling and sensory functions. To elucidate processes of their construction we take advantage of high experimental tractability of the flagellated parasite Trypanosoma brucei. Due to high evolutionary conservation of the flagella and cilia we are able to apply the knowledge acquired from studying this divergent eukaryote to mammalian models. Furthermore, to gain a mechanistic insight into activities of proteins we identified as being critical, we study them by in vitro biochemical approaches. Integrating results from these experiments will provide a comprehensive understanding of the processes underlying construction of these intriguing organelles.