Nostoc Colony (Simplified)
Nostoc is a prokaryotic, unbranched, filamentous, colonial blue-green alga belonging to the class Cyanophyceae. It is commonly known as star jelly, witches' butter, or mars egg. This alga is found in both aquatic and terrestrial habitats and exists in a haploid form. The colony of Nostoc is globular and jelly-like, ranging in size from that of a pea seed to a plum fruit. It is surrounded by an outer firm gelatinous layer called the pellicle, which encloses a gelatinous matrix. The center of the colony remains hollow. Within the gelatinous matrix, numerous filaments are present, with each filament referred to as a trichome. These filaments are enclosed by a mucilage sheath and consist of oval cells. The trichome is composed of three types of cells: Vegetative cells Heterocysts Akinetes Each cell is bounded by an outer cell wall and an inner plasma membrane. The cell wall is primarily composed of hemicellulose and pectin, while the plasma membrane encloses the protoplasm. The protopl...