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Chlorophycean algae have chloroplasts and nearly all members are photosynthetic. There are a few exceptions, such as Polytoma, which have plastids that have lost the ability to photosynthesize. [4] They are usually green due to the presence of chlorophyll a and b; they can also contain the pigment beta-carotene.
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]
The chloroplasts of red algae have chlorophylls a and c (often), and phycobilins, while those of green algae have chloroplasts with chlorophyll a and b without phycobilins. Land plants are pigmented similarly to green algae and probably developed from them, thus the Chlorophyta is a sister taxon to the plants; sometimes the Chlorophyta, the ...
Other forms of chlorophyll exist, such as the accessory pigments chlorophyll b, chlorophyll c, chlorophyll d, [12] and chlorophyll f. Chlorophyll b is an olive green pigment found only in the chloroplasts of plants , green algae , any secondary chloroplasts obtained through the secondary endosymbiosis of a green alga, and a few cyanobacteria ...
Cyanobacteria might have also emerged 3.5 Ga ago. [178] Oxygen concentrations in the atmosphere remained around or below 0.001% of today's level until 2.4 Ga ago (the Great Oxygenation Event). [179] The rise in oxygen may have caused a fall in the concentration of atmospheric methane, and triggered the Huronian glaciation from around 2.4 to 2.1 ...
The plastids differ both in their pigmentation and in their ultrastructure. For example, chloroplasts in plants and green algae have lost all phycobilisomes, the light harvesting complexes found in cyanobacteria, red algae and glaucophytes, but instead contain stroma and grana thylakoids. The glaucocystophycean plastid—in contrast to ...
Algae constitute a polyphyletic group since they do not include a common ancestor, and although their chlorophyll-bearing plastids seem to have a single origin (from symbiogenesis with cyanobacteria), they were acquired in different ways. Green algae are a prominent example of algae that have primary chloroplasts derived from endosymbiont ...
Haptophyte chloroplasts contain chlorophylls a, c 1, and c 2 but lack chlorophyll b. For carotenoids, they have beta-, alpha-, and gamma-carotenes. Like diatoms and brown algae, they have also fucoxanthin, an oxidized isoprenoid derivative that is likely the most important driver of their brownish-yellow color. [6]