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Green algae have chloroplasts that contain chlorophyll a and b, giving them a bright green colour, as well as the accessory pigments beta carotene (red-orange) and xanthophylls (yellow) in stacked thylakoids. [12] [13] The cell walls of green algae usually contain cellulose, and they store carbohydrate in the form of starch. [14]
Chlamydomonas reinhardtii is a single-cell green alga about 10 micrometres in diameter that swims with two flagella.It has a cell wall made of hydroxyproline-rich glycoproteins, a large cup-shaped chloroplast, a large pyrenoid, and an eyespot apparatus that senses light.
Diagram of the plant cell, with the cell wall in green. Cell walls serve similar purposes in those organisms that possess them. They may give cells rigidity and strength, offering protection against mechanical stress. The chemical composition and mechanical properties of the cell wall are linked with plant cell growth and morphogenesis. [11]
The content of the cell divides into 2,4 (B), 8(C) sometimes daughter protoplasts. Each daughter protoplast rounds off to form a non-motile spore. These autospores (spores having the same distinctive shape as the parent cell) are liberated by the rupture of the parent cell wall (D). On release each autospore grows to become a new individual.
The chlorophyte and charophyte green algae and the embryophytes or land plants form a clade called the green plants or Viridiplantae, that is united among other things by the absence of phycobilins, the presence of chlorophyll a and chlorophyll b, cellulose in the cell wall and the use of starch, stored in the plastids, as a storage polysaccharide.
Eventually the mother cell wall breaks and releases the spores which adopt a normal cellular appearance. [6] The cells at either end of the coenobium are different in morphology from those in the center. [6] How the cells adhere to one another during development is still unclear, but it is known that a trilaminar sheath (TLS), composed of ...
Desmodesmus species usually produce colonies of more than one cell, but single cells (unicells) may be found as well. [5] These single cells may be confused with Lagerheimia, a genus of single-celled algae. [6] The cell wall of Desmodesmus consists of an outer layer with a net-like structure, with "rosettes" of tubes underneath. [7]
The structure of these algae is unicellular, and lacks flagella.Although most desmid species are unicellular, some genera form chains of cells, called filaments. A few genera form non-filamentous colonies, with individual cells connected by threads or remnants of parent cell walls.