of the two major functions of carotenoids in photosynthesis, ..

The unicellular cyanobacterium Synechocystis sp. PCC6803 was the third prokaryote and first photosynthetic organism whose genome was completely sequenced. It continues to be an important model organism. The smallest genomes have been found in Prochlorococcus spp. (1.7 Mb) and the largest in Nostoc punctiforme (9 Mb). Those of Calothrix spp. are estimated at 12–15 Mb, as large as yeast.

Functions of carotenoids in photosynthesis

PCC 7120 and Nostoc punctiforme PCC 73102, and proposal for the biosynthetic pathway of carotenoids

How carotenoids function in photosynthetic ..

Among CARs β-carotene and several xanthophylls serve as constituents of functional multiprotein complexes, such as photosystems I and II (PSI, PSII), cytochrome b 6 / f complexes, and the light-harvesting complexes involved in photosynthetic electron transport.

BBA 86145 How carotenoids function in photosynthetic bacteria ..

The complex of regulatory reactions based on negative and positive feedback principles provides prolonged functioning of a chloroplast and high stability of photosynthetic activity under various light conditions.">

Perturbations of carotenoid and tetrapyrrole biosynthetic pathways result in ..

chlorophylls and carotenoids with peaks ..

Their specific colour depends on metal ions and pH.
• Carotenoids are lipid-soluble pigments, and are involved in harvesting light in photosynthesis.

In vivo functions of carotenoids ..

Light energy in the form of photons is harvested by systems of in pigment molecules. Because each pigment can only absorb photons with an energy that exactly matches the amount to excite an electron to an excited state, each pigment has a characteristic color. Both chlorophyll and carotenoid pigments are produced in biosynthetic pathways that also produce other important biomolecules.

The chlorophyll and carotenoid molecules are organized in the membranes into two photosystems. Most of the pigments in each act as and harvest light. A few specialized pigments form the reaction centers and carry out the photochemical electron transfers. Absorption of light by the two photosystems excites electrons in two steps and transfers them from water to the NADPH; two photosystems are required because the energy difference between the electrons in water and NADPH is greater than the energy in a single . Simultaneously, the pumps protons across the photosynthetic membrane, providing the energy to synthesize ATP. With sufficient quantities of NADPH and ATP, the chloroplast is able to complete the process of photosynthesis by producing sugars from CO2.

(redox) reactions involving electron transfer ; Photosynthesis is a two stage process.

for chlorophylls and carotenoids with peaks ..

A pigment is a generic term for a molecule that absorbs light and has a color. Plants contain many pigments, giving rise to the various colors we see. Flowers and fruits obviously contain a large number of organic molecules that absorb light. Leaves, stems and roots also contain a variety of pigments. Such pigment molecules include anthocyanins, flavanoids, flavines, quinones and cytochromes, just to name a few. However, none of these should be considered a photosynthetic pigment. Photosynthetic pigments are the only pigments that have the ability to absorb energy from sunlight and make it available to the photosynthetic apparatus. In land plants, there are two classes of these photosynthetic pigments, the chlorophylls and the carotenoids.

07/09/2011 · The photochemistry and function of carotenoids ..

III Optical Properties of Carotenoids in Relation to Functions

Chloroplasts found in eukaryotes (algae and plants) likely evolved from an endosymbiotic relation with cyanobacteria. This endosymbiotic theory is supported by various structural and genetic similarities. Primary chloroplasts are found among the "true plants" or green plants – species ranging from sea lettuce to evergreens and flowers which contain chlorophyll b – as well as among the red algae and glaucophytes, marine species which contain phycobilins. It now appears that these chloroplasts probably had a single origin, in an ancestor of the clade called Primoplantae. Other algae likely took their chloroplasts from these forms by secondary endosymbiosis or ingestion.

Frank HA, Brudvig GW (2004) Redox functions of carotenoids in photosynthesis

Optical Properties of Carotenoids in Relation to Functions.- IV.

Cyanobacteria have an elaborate and highly organized system of internal membranes which function in photosynthesis. Cyanobacteria get their colour from the bluish pigment phycocyanin, which they use to capture light for photosynthesis. Photosynthesis in cyanobacteria generally uses water as an electron donor and produces oxygen as a by-product, though some may also use hydrogen sulfide as occurs among other photosynthetic bacteria. Carbon dioxide is reduced to form carbohydrates via the Calvin cycle. In most forms the photosynthetic machinery is embedded into folds of the cell membrane, called thylakoids. The large amounts of oxygen in the atmosphere are considered to have been first created by the activities of ancient cyanobacteria. Due to their ability to fix nitrogen in aerobic conditions they are often found as symbionts with a number of other groups of organisms such as fungi (lichens), corals, pteridophytes (Azolla), angiosperms (Gunnera) etc.