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| Chloroplast of Chlamydomonas, a unicellular green alga. Note the chloroplast (Chl) with stacked thylakoids, and starch (s). TEM image by Richard Pienaar. |
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| Chloroplast of Chlamydomonas, a unicellular green alga. Note the chloroplast (Chl) with stacked thylakoids, and starch (s). TEM image by Richard Pienaar. |
The Chlorophyta
The Chlorophyta, or green algae, includes a around 7000 species of algae with representatives
in almost every habitat on earth. They are characterized by the presence of chlorophyll-a and chlorophyll-b, the absence of phycobiliprotein accessory pigments, and the presence of carotenoid accessory pigments. The cell wall is composed of cellulose, hemicellulose and pectins. Food is stored as starch that is clustered around pyrenoids or scattered throughout chloroplast stroma.
The chloroplast membrane is 2-layered, the thylakoids are stacked in groups of two or more that are organized into lamellae, pseudograna, or grana.
Characteristics
of the Chlorophyta |
|
| Main pigments |
Chlorophyll-a and Chlorophyll-b, alpha, ß and gamma Carotene, Xanthophylls (lutein, siphonoxanthin, siphonein); Chlorophyll-c is usually not present except in some Prasinophyceae |
| Nuclear material |
Organised into membrane-bound nucleus |
| Food reserves | Starch, clustered around pyrenoids or scattered throughout chloroplast stroma. |
| Chloroplast features | Chloroplast present, membrane 2-layered, the thylakoids are stacked in groups of two or more organized into lamellae, pseudograna, or grana; no girdle lamellae |
| chloroplast endoplasmic reticulum | absent |
| Cell wall | Cellulose, some naked, some with calcification |
| Flagella | When present, lack the tubular hairs of haptophytes, but may have scales or hairs; apically inserted, similar in structure, maybe two, four, or many (stephanokont) |
