Photosynthesis is the conversion of light energy into chemical energy by living organisms. Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός The raw materials are carbon dioxide and water; the energy source is sunlight; and the end-products are oxygen and (energy rich) carbohydrates, for example sucrose, glucose and starch. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Water is a common Chemical substance that is essential for the survival of all known forms of Life. Sunlight, in the broad sense is the total spectrum of the Electromagnetic radiation given off by the Sun. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most Solubility of Pure SucroseTemperature(Cg Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. Starch, CAS # 9005-25-8 Chemical formula (C6H10O5n is a Polysaccharide This process is arguably the most important biochemical pathway,^[1] since nearly all life on Earth either directly or indirectly depends on it. In Biochemistry, a metabolic pathway is a series of chemical reactions occurring within a cell. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 It is a complex process occurring in higher plants, algae, as well as bacteria such as cyanobacteria. Plants are living Organisms belonging to the kingdom Plantae. Algae ( sing. alga are a large and diverse group of simple typically Autotrophic organisms ranging from Unicellular to Multicellular forms The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy Photosynthetic organisms are also referred to as photoautotrophs. Photoautotrophs or Phototroph ( Gk: photo = light auto = self troph = nourishment are Organisms (commonly plants that carry out Photosynthesis ^[1]

The word comes from the Greek φώτο- (photo-), "light," and σύνθεσις (synthesis), "putting together. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly "

Contents 1 Overview 1.1 In plants 1.2 In algae and bacteria 2 Evolution 2.1 Origin of chloroplasts 2.2 Cyanobacteria and the evolution of photosynthesis 3 Molecular production 3.1 Light to chemical energy 3.1.1 Z scheme 3.1.2 Water photolysis 3.1.3 Quantum mechanical effects 3.1.4 Oxygen and photosynthesis 3.1.5 Bacterial variation 3.2 Carbon fixation 3.3 C4, C3 and CAM 4 Discovery 5 Factors 5.1 Light intensity (Irradiance), wavelength and temperature 5.2 Carbon dioxide levels and photorespiration 6 See also 7 Notes 8 References 9 External links

Overview

Photosynthesis uses light energy and carbon dioxide to make triose phospates (G3P). Glyceraldehyde 3-phosphate, also known as triose phosphate or 3-phosphoglyceraldehyde and abbreviated as G3P, GADP, GAP or PGAL G3P is generally considered the prime end-product of photosynthesis. It can be used as an immediate food nutrient, or combined and rearranged to form disaccharide sugars, such as sucrose, which can be transported to other cells, or stored as insoluble polysaccharides such as starch. A disaccharide is a Sugar (a Carbohydrate) composed of two Monosaccharides 'Disaccharide' is one of the four chemical groupings of carbohydrates ( Solubility of Pure SucroseTemperature(Cg Polysaccharides are relatively complex Carbohydrates They are Polymers made up of many Monosaccharides joined together by Glycosidic bonds Starch, CAS # 9005-25-8 Chemical formula (C6H10O5n is a Polysaccharide

A commonly used but slightly simplified equation for photosynthesis is:

6 CO_2(g) + 12 H₂O_(l) + photons → C₆H₁₂O_6(aq) + 6 O_2(g) + 6 H₂O_(l)

carbon dioxide + water + light energy → glucose + oxygen + water

When written as a word equation the light energy appears above the arrow as it is required for photosynthesis but it is not actually a reactant. A chemical equation is a symbolic representation of a Chemical reaction. In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. Here the monosaccharide glucose is shown as a product, although the actual processes in plants produce disaccharides. Monosaccharides (from Greek monos: single sacchar: sugar are the most basic unit of Carbohydrates They consist of one sugar and Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. A disaccharide is a Sugar (a Carbohydrate) composed of two Monosaccharides 'Disaccharide' is one of the four chemical groupings of carbohydrates (

The equation is often presented in introductory chemistry texts in an even more simplified form as:^[2]

6 CO_2(g) + 6 H₂O_(l) + photons → C₆H₁₂O_6(aq) + 6 O_2(g)

Photosynthesis occurs in two stages. In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena In the first phase, light-dependent reactions or photosynthetic reactions (also called the Light reactions) capture the energy of light and use it to make high-energy molecules. During the second phase, the light-independent reactions (also called the Calvin-Benson Cycle, and formerly known as the Dark Reactions) use the high-energy molecules to capture carbon dioxide (CO₂) and make the precursors of carbohydrates. The Calvin cycle (or Calvin-Benson-Bassham cycle or carbon fixation is a series of biochemical reactions that takes place in the Stroma of Chloroplasts Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single In Chemistry, a precursor is a compound that participates in the Chemical reaction that produces another compound Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most

In the light reactions, one molecule of the pigment chlorophyll absorbs one photon and loses one electron. The initial stage of the photosynthetic system is the light-dependent reaction, which converts solar energy into Potential energy. For the drug referred to as "pigment" see Black tar heroin. Chlorophyll is a green Pigment found in most Plants Algae and Cyanobacteria. In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J This electron is passed to a modified form of chlorophyll called pheophytin, which passes the electron to a quinone molecule, allowing the start of a flow of electrons down an electron transport chain that leads to the ultimate reduction of NADP into NADPH. Pheophytin or Pheo is a Chlorophyll molecule lacking a central Mg2+ ion which serves as the first electron carrier intermediate in "DDQ" redirects here DDQ is also the former callsign of a TV station in Toowoomba Queensland Australia An electron transport chain couples a chemical reaction between an electron donor (such as NADH) and an electron acceptor (such as O2) to the transfer Nicotinamide adenine dinucleotide phosphate ( NADP+, in older notation triphosphopyridine nucleotide TPN) is used in anabolic reactions such as Lipid Nicotinamide adenine dinucleotide phosphate ( NADP+, in older notation triphosphopyridine nucleotide TPN) is used in anabolic reactions such as Lipid In addition, it serves to create a proton gradient across the chloroplast membrane; its dissipation is used by ATP Synthase for the concomitant synthesis of ATP. In Cellular biology, an electrochemical gradient is a spatial variation of both Electrical potential and chemical Concentration across a membrane Chloroplasts contain several important membranes vital for their function An ATP synthase ( is a general term for an Enzyme that can synthesize Adenosine triphosphate (ATP from Adenosine diphosphate (ADP and inorganic Adenosine-5'-triphosphate ( ATP) is a multifunctional Nucleotide that is most important as a " molecular currency" of intracellular Energy The chlorophyll molecule regains the lost electron by taking one from a water molecule through a process called photolysis, that releases oxygen gas. Water is a common Chemical substance that is essential for the survival of all known forms of Life. Photodissociation, photolysis, or photodecomposition is a Chemical reaction in which a Chemical compound is broken down by Photons Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the

In the Light-independent or dark reactions the enzyme RuBisCO captures CO₂ from the atmosphere and in a process that requires the newly-formed NADPH, called the Calvin-Benson cycle releases three-carbon sugars, which are later combined to form sucrose and starch. In Photosynthesis, the light-independent reactions, also somewhat misleadingly called the dark reactions (they don't require darkness but they require the Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins Ribulose-15-bisphosphate carboxylase/oxygenase, most commonly known by the shorter name RuBisCO, is an Enzyme ( that is used in the Calvin cycle Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five The Calvin cycle (or Calvin-Benson-Bassham cycle or carbon fixation is a series of biochemical reactions that takes place in the Stroma of Chloroplasts

Photosynthesis may simply be defined as the conversion of light energy into chemical energy by living organisms. In Thermodynamics, chemical thermodynamics is the mathematical study of the interrelation of Heat and work with Chemical reactions or with a It is affected by its surroundings and the rate of photosynthesis is affected by the concentration of carbon dioxide, the intensity of light, and the temperature. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature

In plants

Most plants are photoautotrophs, which means that they are able to synthesize food directly from inorganic compounds using light energy - for example from the sun, instead of eating other organisms or relying on nutrients derived from them. Photoautotrophs or Phototroph ( Gk: photo = light auto = self troph = nourishment are Organisms (commonly plants that carry out Photosynthesis In Chemistry, chemical synthesis is purposeful execution of Chemical reactions in order to get a product, or several products Traditionally inorganic compounds are considered to be of mineral not biological origin This is distinct from chemoautotrophs that do not depend on light energy, but use energy from inorganic compounds. Chemotrophs are organisms that obtain Energy by the Oxidation of Electron donating Molecules in their environments

6 CO₂ + 12 H₂O → C₆H₁₂O₆ + 6 O₂ + 6 H₂O

The energy for photosynthesis ultimately comes from absorbed photons and involves a reducing agent, which is water in the case of plants, releasing oxygen as a waste product. In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena A reducing agent (also called a reductant or reducer) is the element or a compound in a Redox (reduction-oxidation reaction (see Electrochemistry Water is a common Chemical substance that is essential for the survival of all known forms of Life. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the The light energy is converted to chemical energy (known as light-dependent reactions), in the form of ATP and NADPH, which are used for synthetic reactions in photoautotrophs. The initial stage of the photosynthetic system is the light-dependent reaction, which converts solar energy into Potential energy. Adenosine-5'-triphosphate ( ATP) is a multifunctional Nucleotide that is most important as a " molecular currency" of intracellular Energy Nicotinamide adenine dinucleotide phosphate ( NADP+, in older notation triphosphopyridine nucleotide TPN) is used in anabolic reactions such as Lipid The overall equation for the light-dependent reactions under the conditions of non-cyclic electron flow in green plants is:^[3]

2 H₂O + 2 NADP⁺ + 2 ADP + 2 P_i + light → 2 NADPH + 2 H⁺ + 2 ATP + O₂

Most notably, plants use the chemical energy to fix carbon dioxide into carbohydrates and other organic compounds through light-independent reactions. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most In Photosynthesis, the light-independent reactions, also somewhat misleadingly called the dark reactions (they don't require darkness but they require the The overall equation for carbon fixation (sometimes referred to as carbon reduction) in green plants is:^[3]

3 CO₂ + 9 ATP + 6 NADPH + 6 H⁺ → C₃H₆O₃-phosphate + 9 ADP + 8 P_i + 6 NADP⁺ + 3 H₂O

To be more specific, carbon fixation produces an intermediate product, which is then converted to the final carbohydrate products. The carbon skeletons produced by photosynthesis are then variously used to form other organic compounds, such as the building material cellulose, as precursors for lipid and amino acid biosynthesis, or as a fuel in cellular respiration. Cellulose is an Organic compound with the formula, a Polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4 Lipids are broadly defined as any fat- Soluble ( lipophilic) naturally-occurring Molecule, such as fats oils waxes cholesterol sterols fat-soluble In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this Cellular respiration is the set of the metabolic reactions and processes that take place in Organisms cells to convert biochemical energy from The latter occurs not only in plants but also in animals when the energy from plants gets passed through a food chain. Food chains, also called food networks and/or trophic networks, describe the feeding relationships between species within an Ecosystem. Organisms dependent on photosynthetic and chemosynthetic organisms are called heterotrophs. Chemosynthesis is the biological conversion of one or more carbon molecules (usually Carbon dioxide or Methane) and nutrients into organic matter using the Oxidation A heterotrophs, or chemoorganotrophy ( Greek heterone = (another and trophe = nutrition is an Organism that requires In general outline, cellular respiration is the opposite of photosynthesis: Glucose and other compounds are oxidized to produce carbon dioxide, water, and chemical energy. However, the two processes take place through a different sequence of chemical reactions and in different cellular compartments.

Plants absorb light primarily using the pigment chlorophyll, which is the reason that most plants have a green color. For the drug referred to as "pigment" see Black tar heroin. Chlorophyll is a green Pigment found in most Plants Algae and Cyanobacteria. The function of chlorophyll is often supported by other accessory pigments such as carotenes and xanthophylls. Accessory pigments are light-absorbing compounds found in Photosynthetic Organisms that work in conjunction with Chlorophyll a. The term carotene is used for several related substances having the formula C40H56 Xanthophylls (originally phylloxanthins) are yellow Pigments from the Carotenoid group Both chlorophyll and accessory pigments are contained in organelles (compartments within the cell) called chloroplasts. In Cell biology, an organelle (pronunciation /ɔː(rgəˡnɛl/ is a specialized subunit within a cell that has a specific function and is usually separately enclosed The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called Chloroplasts are Organelles found in Plant cells and eukaryotic Algae that conduct Photosynthesis. Although all cells in the green parts of a plant have chloroplasts, most of the energy is captured in the leaves. In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis. The cells in the interior tissues of a leaf, called the mesophyll, can contain between 450,000 and 800,000 chloroplasts for every square millimeter of leaf. In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis. The surface of the leaf is uniformly coated with a water-resistant waxy cuticle that protects the leaf from excessive evaporation of water and decreases the absorption of ultraviolet or blue light to reduce heating. Wax has traditionally referred to a substance that is secreted by Bees ( Beeswax) and used by them in constructing their Plant cuticles are a protective waxy covering produced only by the epidermal cells of leaves, young shoots and all other aerial plant organs without Periderm Evaporation is the process by which Molecules in a Liquid state (e Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays Blue is a Colour, the Perception of which is evoked by Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature The transparent epidermis layer allows light to pass through to the palisade mesophyll cells where most of the photosynthesis takes place. In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis. In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis.

Plants convert light into chemical energy with a maximum photosynthetic efficiency of approximately 6%. Plants are living Organisms belonging to the kingdom Plantae. In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός The photosynthetic efficiency is the fraction of light energy converted into other forms of energy for use ^[4][5][6] By comparison solar panels convert light into electric energy at a photosynthetic efficiency of approximately 10-20%. In the field of Photovoltaics, a photovoltaic module is a packaged interconnected assembly of photovoltaic cells also known as Solar cells An installation of Electric energy is the potential energy associated with the conservative Coulomb forces between Charged particles contained within a system, where Actual plant's photosynthetic efficiency varies with the frequency of the light being converted, light intensity, temperature and proportion of CO₂ in atmosphere. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single

In algae and bacteria

Algae come in multiple forms from multicellular organisms like kelp, to microscopic, single-cell organisms. Kelp are large Seaweeds ( Algae) belonging to the Brown algae and classified in the order Laminariales Microscopy is the technical field of using microscopes to view samples or objects A microorganism (also spelled micro organism or micro-organism and also called a microbe) is an Organism that is Microscopic (usually Although they are not as complex as land plants, the biochemical process of photosynthesis is the same. Very much like plants, algae have chloroplasts and chlorophyll, but various accessory pigments are present in some algae such as phycocyanin, carotenes, and xanthophylls in green algae and phycoerythrin in red algae (rhodophytes), resulting in a wide variety of colors. Accessory pigments are light-absorbing compounds found in Photosynthetic Organisms that work in conjunction with Chlorophyll a. Phycocyanin is a Pigment from the light-harvesting Phycobiliprotein family along with Allophycocyanin and Phycoerythrin. The term carotene is used for several related substances having the formula C40H56 Xanthophylls (originally phylloxanthins) are yellow Pigments from the Carotenoid group The green algae (singular green alga) are the large group of Algae from which the Embryophytes (higher plants emerged Phycoerythrin is a Red Protein from the light-harvesting Phycobiliprotein family present in Cyanobacteria, Red algae and cryptomonads The red algae (Rhodophyta ˌroʊdəˈfaɪtə roʊˈdɒfɨtə from Greek: ῥόδον (rhodon = rose + φυτόν (phyton = plant thus red plant are Brown algae and diatoms contain fucoxanthol as their primary pigment. The Phaeophyceae or brown algae, (singular alga is a large group of mostly marine multicellular Algae including many Seaweeds of colder Diatoms ( Greek: (dia = "through" + (temnein = "to cut" i All algae produce oxygen, and many are autotrophic. An autotroph (from the Greek autos = self and trophe = nutrition is an Organism that produces complex Organic compounds from simple However, some are heterotrophic, relying on materials produced by other organisms. For example, in coral reefs, there is a mutualistic relationship between zooxanthellae and the coral polyps. Coral reefs are Aragonite structures produced by living organisms found in marine waters with little to no nutrients in the water Mutualism is a Biological interaction between individuals of two different Species, where both individuals derive a fitness benefit for example increased Zooxanthellae (plural ˌzoʊoʊzænˈθɛli are golden-brown intracellular Endosymbionts of various marine Animals and Protozoa, especially Anthozoans In Zoology, a polyp is one of two forms of individuals found in many species of Cnidarians The two are the polyp or hydroid and the medusa. ^[7]

Photosynthetic bacteria do not have chloroplasts (or any membrane-bound organelles). In Cell biology, an organelle (pronunciation /ɔː(rgəˡnɛl/ is a specialized subunit within a cell that has a specific function and is usually separately enclosed Instead, photosynthesis takes place directly within the cell. Cyanobacteria contain thylakoid membranes very similar to those in chloroplasts and are the only prokaryotes that perform oxygen-generating photosynthesis. Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy A Thylakoid is a membrane-bound compartment inside Chloroplasts and cyanobacteria. In fact, chloroplasts are now considered to have evolved from an endosymbiotic bacterium, which was also an ancestor of cyanobacterium. eVolution is the third Album by eLDee, it was due to be released in 2008 An endosymbiont is any Organism that lives within the body or cells of another organism i The other photosynthetic bacteria have a variety of different pigments, called bacteriochlorophylls, and do not produce oxygen. Bacteriochlorophylls are Photosynthetic pigments that occur in various Phototrophic bacteria. Some bacteria, such as Chromatium, oxidize hydrogen sulfide instead of water for photosynthesis, producing sulfur as waste. The Chromatium are a Gram-negative Bacterium found in Water, they are also called purple sulphur bacteria Hydrogen sulfide (or hydrogen sulphide) is the Chemical compound with the formula H 2 S. Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16

Evolution

The ability to convert light energy to chemical energy confers a significant evolutionary advantage to living organisms. Natural selection is the process by which favorable Heritable traits become more common in successive Generations of a Population of Early photosynthetic systems, such as those from green and purple sulfur and green and purple non-sulfur bacteria, are thought to have been anoxygenic, using various molecules as electron donors. The green sulfur bacteria are a family of obligately anaerobic Photoautotrophic bacteria. The purple sulfur bacteria are a group of Proteobacteria capable of Photosynthesis, collectively referred to as Purple bacteria. Purple bacteria or purple photosynthetic bacteria are Proteobacteria that are Phototrophic i An electron donor is a chemical entity that donates Electrons to another compound Green and purple sulfur bacteria are thought to have used hydrogen and sulfur as an electron donor. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Sulfur or sulphur (ˈsʌlfɚ see spelling below) is the Chemical element that has the Atomic number 16 Green nonsulfur bacteria used various amino and other organic acids. In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this An organic acid is an Organic compound with Acidic properties Purple nonsulfur bacteria used a variety of non-specific organic molecules. The use of these molecules is consistent with the geological evidence that the atmosphere was highly reduced at that time. A hydric soil is a soil that formed under conditions of saturation flooding or ponding long enough during the growing season to develop anaerobic conditions in the upper part The history of Earth covers approximately 46 billion years (4567000000 years from Earth ’s formation out of the Solar nebula to the present

Fossils of what are thought to be filamentous photosynthetic organisms have been dated at 3. In Biology, a filament is a long chain of Protein subunits such as those found in hair muscle or in Flagella. 4 billion years old. ^[8]

Oxygen in the atmosphere exists due to the evolution of oxygenic photosynthesis, sometimes referred to as the oxygen catastrophe. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five Oxygen evolution is the process of generating molecular Oxygen through Chemical reaction. The Oxygen Catastrophe was a massive environmental change believed to have happened during the Siderian period at the beginning of the Paleoproterozoic Geological evidence suggests that oxygenic photosynthesis, such as that in cyanobacteria, became important during the Paleoproterozoic era around 2 billion years ago. Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy The Paleoproterozoic (ˌpeɪlɪoʊˌproʊtərəˈzoʊɪk also spelled Palaeoproterozoic) is the first of the three sub-divisions ( eras) of the Modern photosynthesis in plants and most photosynthetic prokaryotes is oxygenic. Oxygenic photosynthesis uses water as an electron donor which is oxidized into molecular oxygen by the absorption of a photon by the photosynthetic reaction center. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena A photosynthetic reaction center is a complex of three types of protein that is the site where molecular excitations originating from sunlight are transformed into a series of electron-transfer

Origin of chloroplasts

In plants the process of photosynthesis occurs in organelles called chloroplasts. In Cell biology, an organelle (pronunciation /ɔː(rgəˡnɛl/ is a specialized subunit within a cell that has a specific function and is usually separately enclosed Chloroplasts are Organelles found in Plant cells and eukaryotic Algae that conduct Photosynthesis. Chloroplasts have many similarities with photosynthetic bacteria including a circular chromosome, prokaryotic-type ribosomes, and similar proteins in the photosynthetic reaction center. Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy A chromosome is an organized structure of DNA and Protein that is found in cells. Ribosomes ( from ribo nucleic acid and "Greek soma ( meaning body") are complexes of RNA and Protein that

The endosymbiotic theory suggests that photosynthetic bacteria were acquired (by endocytosis or gene fusion) by early eukaryotic cells to form the first plant cells. The endosymbiotic theory concerns the origins of mitochondria and Plastids (e Endocytosis is a process where cells absorb material ( Molecules such as proteins from the outside by engulfing it with their Cell membrane. A fusion gene is a hybrid gene formed from two previously separate genes Animals Plants fungi, and Protists are eukaryotes (juːˈkærɪɒt or -oʊt Organisms whose cells are organized into complex Plants are living Organisms belonging to the kingdom Plantae. In other words, chloroplasts may simply be primitive photosynthetic bacteria adapted to life inside plant cells, whereas plants themselves have not actually evolved photosynthetic processes on their own. Another example of this can be found in complex plants and animals, including humans, whose cells depend upon mitochondria as their energy source; mitochondria are thought to have evolved from endosymbiotic bacteria, related to modern Rickettsia bacteria. In Cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed Organelle found in most eukaryotic cells. Rickettsia is a Genus of motile, Gram-negative, non-sporeforming, highly Pleomorphic bacteria that can present Both chloroplasts and mitochondria actually have their own DNA, separate from the nuclear DNA of their animal or plant host cells.

This contention is supported by the finding that the marine molluscs Elysia viridis and Elysia chlorotica seem to maintain a symbiotic relationship with chloroplasts from algae with similar RDA structures that they encounter. Molluscs are animals belonging to the phylum Mollusca. There are around 250000 extant Species within the phylum with an estimated 70000 Elysia viridis is a small-to-medium-sized Species of green sea Slug, a marine Opisthobranch Gastropod Mollusk Elysia chlorotica is a small-to-medium-sized Species of green sea Slug, a marine Opisthobranch Gastropod Mollusk This article is about the biological phenomenon for other uses see Symbiosis (disambiguation The term symbiosis (from the Greek However, they do not transfer these chloroplasts to the next generations.

Cyanobacteria and the evolution of photosynthesis

The biochemical capacity to use water as the source for electrons in photosynthesis evolved once, in a common ancestor of extant cyanobacteria. Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy The geological record indicates that this transforming event took place early in our planet's history, at least 2450-2320 million years ago (Ma), and possibly much earlier. Geobiological interpretation of Archean (>2500 Ma) sedimentary rocks remains a challenge; available evidence indicates that life existed 3500 Ma, but the question of when oxygenic photosynthesis evolved continues to engender debate and research. A clear paleontological window on cyanobacterial evolution opened about 2000 Ma, revealing an already-diverse biota of blue-greens. eVolution is the third Album by eLDee, it was due to be released in 2008 Cyanobacteria remained principal primary producers throughout the Proterozoic Eon (2500-543 Ma), in part because the redox structure of the oceans favored photautotrophs capable of nitrogen fixation. Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth. Nitrogen fixation is the process by which Nitrogen is taken from its natural relatively inert molecular form (N2 in the atmosphere and converted into Green algae joined blue-greens as major primary producers on continental shelves near the end of the Proterozoic, but only with the Mesozoic (251-65 Ma) radiations of dinoflagellates, coccolithophorids, and diatoms did primary production in marine shelf waters take modern form. The green algae (singular green alga) are the large group of Algae from which the Embryophytes (higher plants emerged The Proterozoic (ˌproʊtərəˈzoʊɪk is a geological eon representing a period before the first abundant complex life on Earth. The Mesozoic Era is one of three geologic eras of the Phanerozoic eon. Cyanobacteria remain critical to marine ecosystems as primary producers in oceanic gyres, as agents of biological nitrogen fixation, and, in modified form, as the plastids of marine algae. ^[9]

Molecular production

Light to chemical energy

Main article: Light-dependent reaction

The light energy is converted to chemical energy using the light-dependent reactions. The initial stage of the photosynthetic system is the light-dependent reaction, which converts solar energy into Potential energy. The initial stage of the photosynthetic system is the light-dependent reaction, which converts solar energy into Potential energy. This chemical energy production is about 5-6% efficient, with the majority of the light that strikes a plant reflected and not absorbed. ^[4] However, of the energy that is absorbed, approximately 30-50% is captured as chemical energy. ^[10] The products of the light-dependent reactions are ATP from photophosphorylation and NADPH from photoreduction. The initial stage of the photosynthetic system is the light-dependent reaction, which converts solar energy into Potential energy. Adenosine-5'-triphosphate ( ATP) is a multifunctional Nucleotide that is most important as a " molecular currency" of intracellular Energy The production of ATP using the energy of sunlight is called photophosphorylation. Nicotinamide adenine dinucleotide phosphate ( NADP+, in older notation triphosphopyridine nucleotide TPN) is used in anabolic reactions such as Lipid Both are then utilized as an energy source for the light-independent reactions. In Photosynthesis, the light-independent reactions, also somewhat misleadingly called the dark reactions (they don't require darkness but they require the

Not all wavelengths of light can support photosynthesis. In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. The photosynthetic action spectrum depends on the type of accessory pigments present. Accessory pigments are light-absorbing compounds found in Photosynthetic Organisms that work in conjunction with Chlorophyll a. For example, in green plants, the action spectrum resembles the absorption spectrum for chlorophylls and carotenoids with peaks for violet-blue and red light. An action spectrum is the rate of a physiological activity plotted against Wavelength of Light. A material's absorption spectrum shows the fraction of incident Electromagnetic radiation absorbed by the material over a range of Frequencies. Chlorophyll is a green Pigment found in most Plants Algae and Cyanobacteria. Carotenoids are organic Pigments that are naturally occurring in Chromoplasts of plants and some other photosynthetic Organisms In red algae, the action spectrum overlaps with the absorption spectrum of phycobilins for blue-green light, which allows these algae to grow in deeper waters that filter out the longer wavelengths used by green plants. Phycobilins (from Greek: (phykos meaning "alga" and from Latin: bilis meaning "bile" are Chromophores (light-capturing The non-absorbed part of the light spectrum is what gives photosynthetic organisms their color (e. g. , green plants, red algae, purple bacteria) and is the least effective for photosynthesis in the respective organisms.

Z scheme

In plants, light-dependent reactions occur in the thylakoid membranes of the chloroplasts and use light energy to synthesize ATP and NADPH. The initial stage of the photosynthetic system is the light-dependent reaction, which converts solar energy into Potential energy. A Thylakoid is a membrane-bound compartment inside Chloroplasts and cyanobacteria. Chloroplasts are Organelles found in Plant cells and eukaryotic Algae that conduct Photosynthesis. The light-dependent reaction has two forms; cyclic and non-cyclic reaction. In the non-cyclic reaction, the photons are captured in the light-harvesting antenna complexes of photosystem II by chlorophyll and other accessory pigments (see diagram at right). In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena The light-harvesting (or antenna complex of plants is an array of Protein and Chlorophyll molecules embedded in the Thylakoid membrane which transfer Photosystems (ancient Greek: phos = light and systema = assembly are Protein complexes involved in Photosynthesis. Chlorophyll is a green Pigment found in most Plants Algae and Cyanobacteria. A photosynthetic pigment ( accessory pigment; chloroplast pigment; antenna pigment) is a Pigment that is present in Chloroplasts or When a chlorophyll molecule at the core of the photosystem II reaction center obtains sufficient excitation energy from the adjacent antenna pigments, an electron is transferred to the primary electron-acceptor molecule, Pheophytin, through a process called Photoinduced charge separation. Photoinduced charge separation is the process of an Electron in an Atom being excited to a higher energy level and then leaving the atom to a nearby Electron These electrons are shuttled through an electron transport chain, the so called Z-scheme shown in the diagram, that initially functions to generate a chemiosmotic potential across the membrane. An electron transport chain couples a chemical reaction between an electron donor (such as NADH) and an electron acceptor (such as O2) to the transfer In Cellular biology, an electrochemical gradient is a spatial variation of both Electrical potential and chemical Concentration across a membrane An ATP synthase enzyme uses the chemiosmotic potential to make ATP during photophosphorylation, whereas NADPH is a product of the terminal redox reaction in the Z-scheme. An ATP synthase ( is a general term for an Enzyme that can synthesize Adenosine triphosphate (ATP from Adenosine diphosphate (ADP and inorganic Nicotinamide adenine dinucleotide phosphate ( NADP+, in older notation triphosphopyridine nucleotide TPN) is used in anabolic reactions such as Lipid Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state The electron enters the Photosystem I molecule. The electron is excited due to the light absorbed by the photosystem. Photosystems (ancient Greek: phos = light and systema = assembly are Protein complexes involved in Photosynthesis. A second electron carrier accepts the electron, which again is passed down lowering energies of electron acceptors. An electron acceptor is a chemical entity that accepts Electrons transferred to it from another compound The energy created by the electron acceptors is used to move hydrogen ions across the thylakoid membrane into the lumen. The electron is used to reduce the co-enzyme NADP, which has functions in the light-independent reaction. The cyclic reaction is similar to that of the non-cyclic, but differs in the form that it generates only ATP, and no reduced NADP (NADPH) is created. The cyclic reaction takes place only at photosystem I. Once the electron is displaced from the photosystem, the electron is passed down the electron acceptor molecules and returns back to photosystem I, from where it was emitted, hence the name cyclic reaction.

Water photolysis

Main articles: Photodissociation and Oxygen evolution

The NADPH is the main reducing agent in chloroplasts, providing a source of energetic electrons to other reactions. Photodissociation, photolysis, or photodecomposition is a Chemical reaction in which a Chemical compound is broken down by Photons Oxygen evolution is the process of generating molecular Oxygen through Chemical reaction. A reducing agent (also called a reductant or reducer) is the element or a compound in a Redox (reduction-oxidation reaction (see Electrochemistry Its production leaves chlorophyll with a deficit of electrons (oxidized), which must be obtained from some other reducing agent. The excited electrons lost from chlorophyll in photosystem I are replaced from the electron transport chain by plastocyanin. Photosystems (ancient Greek: phos = light and systema = assembly are Protein complexes involved in Photosynthesis. Plastocyanin is an important copper-containing protein involved in electron-transfer However, since photosystem II includes the first steps of the Z-scheme, an external source of electrons is required to reduce its oxidized chlorophyll a molecules. Photosystems (ancient Greek: phos = light and systema = assembly are Protein complexes involved in Photosynthesis. The source of electrons in green-plant and cyanobacterial photosynthesis is water. Two water molecules are oxidized by four successive charge-separation reactions by photosystem II to yield a molecule of diatomic oxygen and four hydrogen ions; the electron yielded in each step is transferred to a redox-active tyrosine residue that then reduces the photoxidized paired-chlorophyll a species called P680 that serves as the primary (light-driven) electron donor in the photosystem II reaction center. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Tyrosine (abbreviated as Tyr or Y) or 4-hydroxyphenylalanine, is one of the 20 Amino acids that are used by cells to synthesize The oxidation of water is catalyzed in photosystem II by a redox-active structure that contains four manganese ions; this oxygen-evolving complex binds two water molecules and stores the four oxidizing equivalents that are required to drive the water-oxidizing reaction. Catalysis is the process in which the rate of a Chemical reaction is increased by means of a Chemical substance known as a catalyst Manganese (ˈmæŋgəniːz is a Chemical element, designated by the symbol Mn. Oxygen evolution is the process of generating molecular Oxygen through Chemical reaction. Photosystem II is the only known biological enzyme that carries out this oxidation of water. Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins The hydrogen ions contribute to the transmembrane chemiosmotic potential that leads to ATP synthesis. Oxygen is a waste product of light-independent reactions, but the majority of organisms on Earth use oxygen for cellular respiration, including photosynthetic organisms. Cellular respiration is the set of the metabolic reactions and processes that take place in Organisms cells to convert biochemical energy from

Quantum mechanical effects

Through photosynthesis, sunlight energy is transferred to molecular reaction centers for conversion into chemical energy with nearly 100-percent efficiency. The transfer of the solar energy takes place almost instantaneously, so little energy is wasted as heat. However, only 43% of the total solar incident radiation can be used (only light in the range 400-700 nm), 20% of light is blocked by canopy, and plant respiration requires about 33% of the stored energy, which brings down the actual efficiency of photosynthesis to about 6. 6%. ^[6]

A study led by researchers with the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley suggests that long-lived wavelike electronic quantum coherence plays an important part in this instantaneous transfer of energy by allowing the photosynthetic system to simultaneously try each potential energy pathway and choose the most efficient option. The United States Department of Energy ( DOE) is a Cabinet -level department of the United States government responsible for energy policy The Ernest Orlando Lawrence Berkeley National Laboratory ( LBNL) is a U The University of California Berkeley (also referred to as Cal, Berkeley and UC Berkeley) is a major research university located in Berkeley In Physics, coherence is a property of waves that enables stationary (i Results of the study are presented in the April 12, 2007 issue of the journal Nature. Nature is a prominent Scientific journal, first published on 4 November 1869 ^[11]

Oxygen and photosynthesis

With respect to oxygen and photosynthesis, there are two important concepts.

• Plant and cyanobacterial (blue-green algae) cells also use oxygen for cellular respiration, although they have a net output of oxygen since much more is produced during photosynthesis. Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy
• Oxygen is a product of the light-driven water-oxidation reaction catalyzed by photosystem II; it is not generated by the fixation of carbon dioxide. Photosystems (ancient Greek: phos = light and systema = assembly are Protein complexes involved in Photosynthesis. Consequently, the source of oxygen during photosynthesis is water, not carbon dioxide.

Bacterial variation

The concept that oxygen production is not directly associated with the fixation of carbon dioxide was first proposed by Cornelis Van Niel in the 1930s, who studied photosynthetic bacteria. Cornelis Bernardus van Niel ( November 4, 1897, Haarlem &ndash March 10, 1985, Carmel, California) was Aside from the cyanobacteria, bacteria only have one photosystem and use reducing agents other than water. Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of Bacteria that obtain their energy Photosystems (ancient Greek: phos = light and systema = assembly are Protein complexes involved in Photosynthesis. They get electrons from a variety of different inorganic chemicals including sulfide or hydrogen, so for most of these bacteria oxygen is not produced. The term sulfide ( sulphide in British English) refers to several types of Chemical compounds containing Sulfur in its lowest Oxidation Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1

Others, such as the halophiles (an Archaea), produced so-called purple membranes where the bacteriorhodopsin could harvest light and produce energy. Halophiles are Extremophiles that thrive in environments with very high concentrations of Salt. Bacteriorhodopsin is a protein used by Archaea, most notably Halobacteria. The purple membranes was one of the first to be used to demonstrate the chemiosmotic theory: light hit the membranes and the pH of the solution that contained the purple membranes dropped as protons were pumping out of the membrane. Chemiosmosis is the diffusion of Ions across a selectively-permeable membrane

Carbon fixation

Main articles: Carbon fixation and Light-independent reaction

The fixation or reduction of carbon dioxide is a light-independent process in which carbon dioxide combines with a five-carbon sugar, ribulose 1,5-bisphosphate (RuBP), to yield two molecules of a three-carbon compound, glycerate 3-phosphate (GP), also known as 3-phosphoglycerate (PGA). Carbon fixation is a process found in Autotrophs (organisms that produce their own food usually driven by Photosynthesis, whereby Carbon dioxide is changed In Photosynthesis, the light-independent reactions, also somewhat misleadingly called the dark reactions (they don't require darkness but they require the Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Ribulose-15-biphosphate (RuBP is an important substrate involved in Carbon fixation. GP, in the presence of ATP and NADPH from the light-dependent stages, is reduced to glyceraldehyde 3-phosphate (G3P). Adenosine-5'-triphosphate ( ATP) is a multifunctional Nucleotide that is most important as a " molecular currency" of intracellular Energy Nicotinamide adenine dinucleotide phosphate ( NADP+, in older notation triphosphopyridine nucleotide TPN) is used in anabolic reactions such as Lipid Glyceraldehyde 3-phosphate, also known as triose phosphate or 3-phosphoglyceraldehyde and abbreviated as G3P, GADP, GAP or PGAL This product is also referred to as 3-phosphoglyceraldehyde (PGAL) or even as triose phosphate. Glyceraldehyde 3-phosphate, also known as triose phosphate or 3-phosphoglyceraldehyde and abbreviated as G3P, GADP, GAP or PGAL Triose is a 3-carbon sugar (see carbohydrates). A triose is a Monosaccharide containing three Carbon Atoms There are only two trioses an aldotriose ( Glyceraldehyde) and a Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most Most (5 out of 6 molecules) of the G3P produced is used to regenerate RuBP so the process can continue (see Calvin-Benson cycle). The Calvin cycle (or Calvin-Benson-Bassham cycle or carbon fixation is a series of biochemical reactions that takes place in the Stroma of Chloroplasts The 1 out of 6 molecules of the triose phosphates not "recycled" often condense to form hexose phosphates, which ultimately yield sucrose, starch and cellulose. In Organic chemistry, a hexose is a Monosaccharide with six Carbon atoms having the Chemical formula C6H12O6 Solubility of Pure SucroseTemperature(Cg Starch, CAS # 9005-25-8 Chemical formula (C6H10O5n is a Polysaccharide Cellulose is an Organic compound with the formula, a Polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4 The sugars produced during carbon metabolism yield carbon skeletons that can be used for other metabolic reactions like the production of amino acids and lipids. Metabolism is the set of Chemical reactions that occur in living Organisms in order to maintain Life. In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this Lipids are broadly defined as any fat- Soluble ( lipophilic) naturally-occurring Molecule, such as fats oils waxes cholesterol sterols fat-soluble

C₄, C₃ and CAM

In hot and dry conditions, plants will close their stomata to prevent loss of water. C4 carbon fixation is one of three biochemical mechanisms along with C3 and CAM photosynthesis, functioning in land Plants to In Botany, a stoma (also stomate; plural stomata) is a tiny opening or pore found mostly on the underside of a Plant Leaf Under these conditions, oxygen gas, produced by the light reactions of photosynthesis, will concentrate in the leaves causing photorespiration to occur. Photorespiration (or "photo-respiration" is the alternate pathway for production of Glyceraldehyde 3-phosphate (G3P by RuBisCO, the main enzyme of the Some plants have evolved mechanisms to increase the CO₂ concentration in the leaves under these conditions. eVolution is the third Album by eLDee, it was due to be released in 2008

C₄ plants capture carbon dioxide using an enzyme called PEP Carboxylase that adds carbon dioxide to the three carbon molecule Phosphoenolpyruvate (PEP) creating the 4-carbon molecule oxaloacetic acid. C4 carbon fixation is one of three biochemical mechanisms along with C3 and CAM photosynthesis, functioning in land Plants to Phosphoenolpyruvate carboxylase (also known as PEP carboxylase, PEPCase, or PEPC; EC 4 Phosphoenolpyruvate (synonyms phosphoenolpyruvic acid, PEP) is an important Chemical compound in Biochemistry. Oxaloacetic acid is an Organic compound with the chemical formula HO2CC(OCH2CO2H Plants without this enzyme are called C₃ plants because the primary carboxylation reaction produces the three-carbon sugar 3-phosphoglycerate directly in the Calvin-Benson Cycle. carbon fixation is a Metabolic pathway for Carbon fixation in Photosynthesis. When oxygen levels rise in the leaf, C4 plants reverse the reaction to release carbon dioxide thus preventing photorespiration. By preventing photorespiration, C₄ plants can produce more sugar than C₃ plants in conditions of strong light and high temperature. Many important crop plants are C₄ plants including maize, sorghum, sugarcane, and millet.

Xerophytes such as cacti and most succulents also can use PEP Carboxylase to capture carbon dioxide in a process called Crassulacean acid metabolism (CAM). A xerophyte or xerophytic organism ( xero meaning dry phyte meaning plant is a Plant which is able to survive in an ecosystem with little available A cactus (plural cacti) is any member of the Spine plant family Cactaceae, native to the Americas Succulent plants, also known as succulents or fat plants, are Water -retaining Plants adapted to Arid climate or Soil conditions Crassulacean acid metabolism, also known as CAM photosynthesis, is an elaborate Carbon fixation pathway in some Plants These plants fix carbon dioxide They store the CO₂ in different molecules than the C₄ plants (mostly they store it in the form of malic acid via carboxylation of phosphoenolpyruvate to oxaloacetate, which is then reduced to malate). Malic acid is an Organic compound with the formula HO2CCH2CHOHCO2H Phosphoenolpyruvate (synonyms phosphoenolpyruvic acid, PEP) is an important Chemical compound in Biochemistry. Nevertheless, C₄ plants capture the CO₂ in one type of cell tissue (mesophyll) and then transfer it to another type of tissue (bundle sheath cells) so that carbon fixation may occur via the Calvin cycle. In Botany, a leaf is an above-ground Plant organ specialized for Photosynthesis. They also have a different leaf anatomy than C₄ plants. They grab the CO₂ at night, when their stomata are open, and they release it into the leaves during the day to increase their photosynthetic rate. C4 metabolism physically separates CO₂ fixation from the Calvin cycle, while CAM metabolism temporally separates CO₂ fixation from the Calvin cycle.

Discovery

Although some of the steps in photosynthesis are still not completely understood, the overall photosynthetic equation has been known since the 1800s.

Jan van Helmont began the research of the process in the mid-1600s when he carefully measured the mass of the soil used by a plant and the mass of the plant as it grew. Jan Baptist van Helmont (bapt January 12, 1579 &ndash December 30, 1644) was an Early modern period Flemish Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object After noticing that the soil mass changed very little, he hypothesized that the mass of the growing plant must come from the water, the only substance he added to the potted plant. His hypothesis was partially accurate - much of the gained mass also comes from carbon dioxide as well as water. However, this was a signaling point to the idea that the bulk of a plant's biomass comes from the inputs of photosynthesis, not the soil itself. Biomass, in Ecology, is the mass of living biological organisms in a given area or Ecosystem at a given time

Joseph Priestley, a chemist and minister, discovered that when he isolated a volume of air under an inverted jar, and burned a candle in it, the candle would burn out very quickly, much before it ran out of wax. Joseph Priestley (13 March 1733 ( Old He further discovered that a mouse could similarly "injure" air. He then showed that the air that had been "injured" by the candle and the mouse could be restored by a plant.

In 1778, Jan Ingenhousz, court physician to the Austrian Empress, repeated Priestley's experiments. Jan Ingenhousz or Ingen-Housz ( December 8, 1730, Breda - September 7, 1799) was Dutch Physiologist Austria (Österreich ( officially the Republic of Austria (Republik Österreich He discovered that it was the influence of sunlight on the plant that could cause it to rescue a mouse in a matter of hours.

In 1796, Jean Senebier, a Swiss pastor, botanist, and naturalist, demonstrated that green plants consume carbon dioxide and release oxygen under the influence of light. Jean Senebier ( May 6, 1742 - July 22, 1809) was a Swiss Pastor who wrote many works on vegetable Physiology Soon afterwards, Nicolas-Théodore de Saussure showed that the increase in mass of the plant as it grows could not be due only to uptake of CO₂, but also to the incorporation of water. Nicolas-Théodore de Saussure ( 14 October 1767 - 18 April 1845) was a Swiss Chemist and student of Plant physiology Thus the basic reaction by which photosynthesis is used to produce food (such as glucose) was outlined.

Cornelis Van Niel made key discoveries explaining the chemistry of photosynthesis. Cornelis Bernardus van Niel ( November 4, 1897, Haarlem &ndash March 10, 1985, Carmel, California) was By studying purple sulfur bacteria and green bacteria he was the first scientist to demonstrate that photosynthesis is a light-dependent redox reaction, in which hydrogen reduces carbon dioxide. The purple sulfur bacteria are a group of Proteobacteria capable of Photosynthesis, collectively referred to as Purple bacteria. Redox (shorthand for reduction-oxidation reaction describes all Chemical reactions in which atoms have their Oxidation number ( Oxidation state

Robert Emerson discovered two light reactions by testing plant productivity using different wavelgnths of light. With the red alone, the light reactions were suppressed. When blue and red were combined, the output was much more substantial. Thus, there were two photosystems, one aborbing up to 600 nm wavelengths, the other up to 700. The former is known as PSII, the latter is PSI. PSI contains only chlorophyll a, PSII contains primarily chlorophyll a with most of the available chlorophyll b, among other pigments. ^[12]

Further experiments to prove that the oxygen developed during the photosynthesis of green plants came from water, were performed by Robert Hill in 1937 and 1939. For other people names Robert Hill see the disambiguation page Robert Hill. He showed that isolated chloroplasts give off oxygen in the presence of unnatural reducing agents like iron oxalate, ferricyanide or benzoquinone after exposure to light. Chloroplasts are Organelles found in Plant cells and eukaryotic Algae that conduct Photosynthesis. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 An oxalate (also ethanedioate) is a salt or Ester of Oxalic acid. Ferricyanide is the name for the Anion 3− Its Systematic name is hexacyanoferrate(III ion The Hill reaction is as follows:

2 H₂O + 2 A + (light, chloroplasts) → 2 AH₂ + O₂

where A is the electron acceptor. Therefore, in light the electron acceptor is reduced and oxygen is evolved. Cyt b₆, now known as a plastoquinone, is one electron acceptor.

Samuel Ruben and Martin Kamen used radioactive isotopes to determine that the oxygen liberated in photosynthesis came from the water. Samuel Ruben (born Charles Rubenstein in San Francisco California, November 5, 1913 - September 28, 1943) the son Martin David Kamen ( August 27, 1913, Toronto &ndash August 31, 2002) was co-discoverer (with Sam Ruben) of the Isotope

Melvin Calvin and Andrew Benson, along with James Bassham, elucidated the path of carbon assimilation (the photosynthetic carbon reduction cycle) in plants. Melvin Ellis Calvin (April 8 1911 - January 8 1997 was an American Chemist most famed for discovering the Calvin cycle along with Andrew Benson Andrew Benson is a scientist who along with Melvin Calvin and James Bassham, elucidated the path of carbon assimilation (the photosynthetic carbon reduction James A Bassham was born in Sacramento California November 26 1922 The carbon reduction cycle is known as the Calvin cycle, which inappropriately ignores the contribution of Bassham and Benson. The Calvin cycle (or Calvin-Benson-Bassham cycle or carbon fixation is a series of biochemical reactions that takes place in the Stroma of Chloroplasts Many scientists refer to the cycle as the Calvin-Benson Cycle, Benson-Calvin, and some even call it the Calvin-Benson-Bassham (or CBB) Cycle.

A Nobel Prize winning scientist, Rudolph A. Marcus, was able to discover the function and significance of the electron transport chain. The Nobel Prize (Nobelpriset (Nobelprisen is a Swedish prize established in the 1895 will of Swedish chemist Alfred Nobel; it was first awarded in Peace, Literature Rudolph "Rudy" Arthur Marcus (born July 21 1923 is an American chemist who received the 1992 Nobel Prize in Chemistry for his theory of Electron transfer

Factors

There are three main factors affecting photosynthesis and several corollary factors. The three main are:

• Light irradiance and wavelength
• Carbon dioxide concentration
• Temperature. Irradiance, radiant emittance, and radiant exitance are Radiometry terms for the power of Electromagnetic radiation at a surface per unit In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single In Chemistry, concentration is the measure of how much of a given substance there is mixed with another substance Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature

Light intensity (Irradiance), wavelength and temperature

In the early 1900s Frederick Frost Blackman along with Gabrielle Matthaei investigated the effects of light intensity (irradiance) and temperature on the rate of carbon assimilation. Frederick Frost Blackman ( 25 July 1866 - 30 January 1947) was a British plant physiologist Irradiance, radiant emittance, and radiant exitance are Radiometry terms for the power of Electromagnetic radiation at a surface per unit

• At constant temperature, the rate of carbon assimilation varies with irradiance, initially increasing as the irradiance increases. However at higher irradiance this relationship no longer holds and the rate of carbon assimilation reaches a plateau.
• At constant irradiance, the rate of carbon assimilation increases as the temperature is increased over a limited range. This effect is only seen at high irradiance levels. At low irradiance, increasing the temperature has little influence on the rate of carbon assimilation.

These two experiments illustrate vital points: firstly, from research it is known that photochemical reactions are not generally affected by temperature. Research is defined as Human activity based on Intellectual application in the investigation of Matter. Photochemistry, a sub-discipline of Chemistry, is the study of the interactions between Atoms, small Molecules, and light (or Electromagnetic radiation Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature However, these experiments clearly show that temperature affects the rate of carbon assimilation, so there must be two sets of reactions in the full process of carbon assimilation. These are of course the light-dependent 'photochemical' stage and the light-independent, temperature-dependent stage. The initial stage of the photosynthetic system is the light-dependent reaction, which converts solar energy into Potential energy. In Photosynthesis, the light-independent reactions, also somewhat misleadingly called the dark reactions (they don't require darkness but they require the Second, Blackman's experiments illustrate the concept of limiting factors. A limiting factor or limiting resource is one that controls a process such as organism growth or species Population size or distribution Another limiting factor is the wavelength of light. Cyanobacteria, which reside several meters underwater, cannot receive the correct wavelengths required to cause photoinduced charge separation in conventional photosynthetic pigments. To combat this problem, a series of proteins with different pigments surround the reaction center. This unit is called a phycobilisome. Phycobilisomes are light harvesting antennae of Photosystem II in Cyanobacteria, Red algae and Glaucophytes.

Carbon dioxide levels and photorespiration

As carbon dioxide concentrations rise, the rate at which sugars are made by the light-independent reactions increases until limited by other factors. In Photosynthesis, the light-independent reactions, also somewhat misleadingly called the dark reactions (they don't require darkness but they require the RuBisCO, the enzyme that captures carbon dioxide in the light-independent reactions, has a binding affinity for both carbon dioxide and oxygen. Ribulose-15-bisphosphate carboxylase/oxygenase, most commonly known by the shorter name RuBisCO, is an Enzyme ( that is used in the Calvin cycle When the concentration of carbon dioxide is high, RuBisCO will fix carbon dioxide. Carbon fixation is a process found in Autotrophs (organisms that produce their own food usually driven by Photosynthesis, whereby Carbon dioxide is changed However, if the oxygen concentration is high, RuBisCO will bind oxygen instead of carbon dioxide. This process, called photorespiration, uses energy, but does not make sugar. Photorespiration (or "photo-respiration" is the alternate pathway for production of Glyceraldehyde 3-phosphate (G3P by RuBisCO, the main enzyme of the

RuBisCO oxygenase activity is disadvantageous to plants for several reasons:

1. One product of oxygenase activity is phosphoglycolate (2 carbon) instead of 3-phosphoglycerate (3 carbon). Phosphoglycolate cannot be metabolized by the Calvin-Benson cycle and represents carbon lost from the cycle. A high oxygenase activity, therefore, drains the sugars that are required to recycle ribulose 5-bisphosphate and for the continuation of the Calvin-Benson cycle. The Calvin cycle (or Calvin-Benson-Bassham cycle or carbon fixation is a series of biochemical reactions that takes place in the Stroma of Chloroplasts
2. Phosphoglycolate is quickly metabolized to glycolate that is toxic to a plant at a high concentration; it inhibits photosynthesis.
3. Salvaging glycolate is an energetically expensive process that uses the glycolate pathway and only 75% of the carbon is returned to the Calvin-Benson cycle as 3-phosphoglycerate.

A highly-simplified summary is:

2 glycolate + ATP → 3-phophoglycerate + carbon dioxide + ADP +NH₃

The salvaging pathway for the products of RuBisCO oxygenase activity is more commonly known as photorespiration, since it is characterized by light-dependent oxygen consumption and the release of carbon dioxide. Photorespiration (or "photo-respiration" is the alternate pathway for production of Glyceraldehyde 3-phosphate (G3P by RuBisCO, the main enzyme of the

See also

Notes

References

• Blankenship, R. E. , 2002. Molecular Mechanisms of Photosynthesis. Blackwell Science.
• Campbell, N. , & Reece, J. , 2005. Biology 7th ed. San Francisco: Benjamin Cummings.
• Gregory, R. P. F. , 1971. Biochemistry of Photosynthesis. Belfast: Universities Press.
• Govindjee, 1975. Bioenergetics of Photosynthesis. New York: Academic Press.
• Govindjee; Beatty, J. T. , Gest, H. and Allen, J. F. (Eds. ), 2005. Discoveries in Photosynthesis. Advances in Photosynthesis and Respiration, Volume 20, Springer.
• Rabinowitch, E. and Govindjee. , 1969. Photosynthesis. New York: John Wiley & Sons, Inc.
• Stern, Kingsley R. , Shelley Jansky, James E Bidlack, 2003. Introductory Plant Biology. McGraw Hill. ISBN 0-07-290941-2

External links

• Science Aid: Photosynthesis Article appropriate for high school science
• Liverpool John Moores University, Dr.David Wilkinson
• Metabolism, Cellular Respiration and Photosynthesis - The Virtual Library of Biochemistry and Cell Biology
• Overall examination of Photosynthesis at an intermediate level
• Overall Energetics of Photosynthesis

© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic