 Chlamydomonas reinhardtii

Chlamydomonas reinhardtii is a unicellular green member of the algae used as a model organism for photosynthesis and for the structure and function of eukaryotic flagella. A typical motile vegetative cell has two anterior flagella, a large cup-shaped chloroplast and a light-sensing eyespot. These features bring propulsion, light sensing and photosynthesis together in one experimentally tractable cell.^[ref]

Its flagella contain the same basic microtubule machinery as motile cilia in animals. This is an evolutionary relationship between organelles; bacterial flagella use a different construction. In the genome study published in 2007, researchers sequenced its nuclear genome and compared predicted proteins across organisms with different cellular capabilities. Genes shared by organisms with flagella, but absent from comparison organisms lacking them, supplied candidates for flagellar assembly and function. Comparisons with proteins experimentally found in flagella helped test those candidates.^[ref]

A photosynthetic alga can therefore illuminate defects in human cilia, while also providing a system for studying chloroplast biology.