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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 ...
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 ...
A chloroplast (/ ˈ k l ɔːr ə ˌ p l æ s t,-p l ɑː s t /) [1] [2] is a type of organelle known as a plastid that conducts photosynthesis mostly in plant and algal cells. Chloroplasts have a high concentration of chlorophyll pigments which capture the energy from sunlight and convert it to chemical energy and release oxygen.
Experimentation with respiratory oxidase inhibitors (for instance, cyanide) on unicellular algae has revealed interactive pathways to be present between chloroplasts and mitochondria. Metabolic pathways responsible for photosynthesis are present in chloroplasts, whereas respiratory metabolic pathways are present in mitochondria.
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 ...
Chlorophyll c refers to forms of chlorophyll found in certain marine algae, including the photosynthetic Chromista (e.g. diatoms and brown algae) and dinoflagellates. [1] [2] [3] These pigments are characterized by their unusual chemical structure, with a porphyrin as opposed to the chlorin (which has a reduced ring D) as the core; they also do not have an isoprenoid tail.