reinhardtii

Chlamydomonas reinhardtii is a unicellular green alga in the phylum Chlorophyta. It is characterized by a biflagellate, motile cell that measures about 10 micrometers in diameter, with a cup-shaped chloroplast that contains a pyrenoid and a light-sensing eyespot. The two anterior flagella enable swimming and phototaxis, allowing movement toward favorable light conditions. It is commonly found in freshwater and damp soils and is widely used in laboratory research because it grows readily in simple media and can be genetically manipulated.

The organism is predominantly haploid during vegetative growth. It reproduces asexually by mitosis and can undergo sexual reproduction in response to nutrient stress, producing zygotes that undergo meiosis to release haploid offspring. The chloroplast and mitochondrion each harbor their own genomes, while the nuclear genome encodes most cellular functions. The species has well-developed genetic and molecular resources, including a fully sequenced nuclear genome and organized tools for transforming both nuclear and organellar genomes.

Chlamydomonas reinhardtii is a major model organism for fundamental aspects of eukaryotic biology. It is used to study photosynthesis, chloroplast gene expression and protein targeting, flagellar structure and motility, and cellular responses to light. Its genetics and cellular biology are supported by extensive community resources, including mutant collections, transcriptomic and proteomic data, and established methods for genetic manipulation.

In research and biotechnology, C. reinhardtii serves as a platform for basic science as well as applied investigations, including studies on bioenergy pathways, carbon fixation, and the production of recombinant proteins. The organism’s ease of cultivation, transparency of results, and tractability under laboratory conditions contribute to its continued prominence in algae research.