Page 135 - Algae

118 Algae: Anatomy, Biochemistry, and Biotechnology

FIGURE 2.80 Transmission electron microscopy image of a chloroplast of Euglena gracilis in longitudinal
section (a) (Bar: 0.10 mm). Deep-etching image of a chloroplast of E. gracilis (b) (Bar: 0.05 mm).

The chloroplasts are never connected to the nucleus by the endoplasmic reticulum, and thylakoids
are usually grouped into threes forming lamellae as in Heterokontophyta and Dynophyta. Girdle
lamellae are never found in this group. The photosynthetic pigments are chlorophylls a and b
with carotenes and xanthophylls as accessory pigments. Chloroplast DNA occurs as tiny granules
throughout the whole stroma.

Chlorarachniophyta

Five to seven bi-lobed chloroplasts are present inside these algae in a peripheral position. Each
chloroplast is bounded by a system of membranes that may appear either as four separate mem-
branes, as a pair of membranes with a sort of flattened vesicles between them, or as three mem-
branes. Four separate membranes are always found near the proximal end of the pyrenoid and