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Encyclopedia > Photosynthesis
Photosynthesis splits water to liberate O2 and fixes CO2 into sugar
Photosynthesis splits water to liberate O2 and fixes CO2 into sugar
The leaf is the primary site of photosynthesis in plants.
The leaf is the primary site of photosynthesis in plants.

Photosynthesis is the conversion of light energy into chemical energy by living organisms. 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. This process is arguably the most important biochemical pathway,[1] since nearly all life either directly or indirectly depends on it. It is a complex process occurring in higher plants, phytoplankton, algae, as well as bacteria such as cyanobacteria. Photosynthetic organisms are also referred to as photoautotrophs.[1] Image File history File links Question_book-3. ... Image File history File links Download high-resolution version (1024x768, 158 KB) Leaf1. ... Image File history File links Download high-resolution version (1024x768, 158 KB) Leaf1. ... Look up foliage in Wiktionary, the free dictionary. ... For other uses, see Light (disambiguation). ... In chemistry, a chemical bond is the force which holds together atoms in molecules or crystals. ... Domains and Kingdoms Nanobes Acytota Cytota Bacteria Neomura Archaea Eukaryota Bikonta Apusozoa Rhizaria Excavata Archaeplastida Rhodophyta Glaucophyta Plantae Heterokontophyta Haptophyta Cryptophyta Alveolata Unikonta Amoebozoa Opisthokonta Choanozoa Fungi Animalia An ericoid mycorrhizal fungus Life on Earth redirects here. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Prism splitting light High Resolution Solar Spectrum Sunlight in the broad sense is the total spectrum of the electromagnetic radiation given off by the Sun. ... This article is about the chemical element and its most stable form, or dioxygen. ... Lactose is a disaccharide found in milk. ... Flash point N/A Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Sucrose (common name: table sugar, also called saccharose) is a disaccharide (glucose + fructose) with the molecular formula C12H22O11. ... Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. ... Starch (CAS# 9005-25-8, chemical formula (C6H10O5)n,[1]) is a mixture of amylose and amylopectin (usually in 20:80 or 30:70 ratios). ... In biochemistry, a metabolic pathway is a series of chemical reactions occurring within a cell, catalyzed by enzymes, resulting in either the formation of a metabolic product to be used or stored by the cell, or the initiation of another metabolic pathway (then called a flux generating step). ... For other uses, see Plant (disambiguation). ... Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of plankton. ... Osborne (talk) 20:17, 5 December 2007 (UTC):For the programming language, see algae (programming language) Laurencia, a marine red alga from Hawaii. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Orders The taxonomy is currently under revision. ... Phototrophs or photoautotrophs are photosynthetic algae, fungi, bacteria and cyanobacteria which build up carbon dioxide and water into organic cell materials using energy from sunlight. ...


The word comes from the Greek photo-, "light", and synthesis, "putting together".

Contents

Overview

Photosynthesis uses light energy and carbon dioxide to make triose phospates (G3P). 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 and fructose, which can be transported to other cells, or packaged for storage as insoluble polysaccharides such as starch. G3P (structure) Glyceraldehyde 3-phosphate (G3P) is an intermediate in both glycolysis and gluconeogenesis. ... Sucrose, a common disaccharide A disaccharide is a sugar (a carbohydrate) composed of two monosaccharides. ... Flash point N/A Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Sucrose (common name: table sugar, also called saccharose) is a disaccharide (glucose + fructose) with the molecular formula C12H22O11. ... Fructose (or levulose) is a simple sugar (monosaccharide) found in many foods and is one of the three most important blood sugars along with glucose and galactose. ... Polysaccharides (sometimes called glycans) are relatively complex carbohydrates. ... Starch (CAS# 9005-25-8, chemical formula (C6H10O5)n,[1]) is a mixture of amylose and amylopectin (usually in 20:80 or 30:70 ratios). ...


A commonly used but slightly simplified equation for photosynthesis is: A chemical equation is a symbolic representation of a chemical reaction. ...

6 CO2(g) + 12 H2O(l) + photonsC6H12O6(aq) + 6 O2(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. Here the monosaccharide glucose is shown as a product, although the actual processes in plants produce disaccharides. In physics, the photon (from Greek φως, phōs, meaning light) is the quantum of the electromagnetic field; for instance, light. ... Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. ... Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. ... Monosaccharides are the simplest form of carbohydrates. ... Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. ...


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

6 CO2(g) + 6 H2O(l) + photons → C6H12O6(aq) + 6 O2(g)

Photosynthesis occurs in two stages. 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. In physics, the photon (from Greek φως, phōs, meaning light) is the quantum of the electromagnetic field; for instance, light. ... Overview of the Calvin cycle and carbon fixation The Calvin cycle (or Calvin-Benson cycle or carbon fixation) is a series of biochemical reactions that takes place in the stroma of chloroplasts in photosynthetic organisms. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... In chemistry a precursor is a compound that participates in the chemical reaction that produces another compound. ... Lactose is a disaccharide found in milk. ...


In the light reactions, one molecule of the pigment chlorophyll absorbs one photon and loses one electron. 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. 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. The chlorophyll molecule regains the lost electron by taking one from a water molecule through a process called photolysis, that releases oxygen gas. The first stage of the photosynthetic system is the light-dependent reaction, which converts solar energy into chemical energy. ... Natural Ultramarine pigment in powdered form. ... Chlorophyll is a green pigment found in most plants, algae, and cyanobacteria. ... In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ... For other uses, see Electron (disambiguation). ... Pheophytin is an accessory pigment in photosystemII of the electron transport chain associated with photosynthesis. ... A quinone (or benzoquinone) is either one of the two isomers of cyclohexadienedione or a derivative thereof. ... The Electron Transport Chain. ... Nicotinamide adenine dinucleotide (NAD+) Nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) are two important coenzymes found in cells. ... Nicotinamide adenine dinucleotide (NAD+) Nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) are two important coenzymes found in cells. ... An ion gradient is a concentration gradient of ions, it can be called an electrochemical potential gradient of ions across membranes. ... Chloroplasts contain several important membranes, vital for their function. ... An ATP synthase (EC 3. ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Photolysis refers to any chemical reaction in which a compound is broken down by light. ... This article is about the chemical element and its most stable form, or dioxygen. ...


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. Overview of the Calvin cycle and carbon fixation In photosynthesis, the light-independent reactions, also somewhat misleadingly called the dark reactions (they dont require darkness, but they do require the products of the light reactions), are chemical reactions that convert carbon dioxide and other compounds into glucose. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Ribulose-1,5-bisphosphate carboxylase/oxygenase, most commonly known by the shorter name RuBisCO, is an enzyme (EC 4. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Air redirects here. ... The Calvin cycle (also known as Calvin-Benson cycle) is a series of biochemical reactions taking place in the chloroplasts of photosynthetic organisms. ...


Photosynthesis may simply be defined as the conversion of light energy into chemical energy by living organisms. 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. Willard Gibbs - founder of chemical thermodynamics In thermodynamics, chemical thermodynamics is the mathematical study of the interrelation of heat and work with chemical reactions or with a physical change of state within the confines of the laws of thermodynamics. ... Domains and Kingdoms Nanobes Acytota Cytota Bacteria Neomura Archaea Eukaryota Bikonta Apusozoa Rhizaria Excavata Archaeplastida Rhodophyta Glaucophyta Plantae Heterokontophyta Haptophyta Cryptophyta Alveolata Unikonta Amoebozoa Opisthokonta Choanozoa Fungi Animalia An ericoid mycorrhizal fungus Life on Earth redirects here. ... For other uses, see Temperature (disambiguation). ...


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. This is distinct from chemoautotrophs that do not depend on light energy, but use energy from inorganic compounds. Phototrophs or photoautotrophs are photosynthetic algae, fungi, bacteria and cyanobacteria which build up carbon dioxide and water into organic cell materials using energy from sunlight. ... 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. ... 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. 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 overall equation for the light-dependent reactions under the conditions of non-cyclic electron flow in green plants is: In modern 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) that reduces another species. ... Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... This article is about the chemical element and its most stable form, or dioxygen. ... Light-dependent reactions of photosynthesis at the thylakoid membrane The initial stage of the photosynthetic system is the light-dependent reaction, which converts solar energy into chemical energy. ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ... Nicotinamide adenine dinucleotide (NAD+) Nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) are two important coenzymes found in cells. ...

2 H2O + 2 NADP+ + 2 ADP + 2 Pi + light → 2 NADPH + 2 H+ + 2 ATP + O2 [3]

Most notably, plants use the chemical energy to fix carbon dioxide into carbohydrates and other organic compounds through light-independent reactions. The overall equation for carbon fixation (sometimes referred to as carbon reduction) in green plants is: Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Lactose is a disaccharide found in milk. ... Overview of the Calvin cycle and carbon fixation In photosynthesis, the light-independent reactions, also somewhat misleadingly called the dark reactions (they dont require darkness, but they do require the products of the light reactions), are chemical reactions that convert carbon dioxide and other compounds into glucose. ...

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

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. The latter occurs not only in plants but also in animals when the energy from plants gets passed through a food chain. Organisms dependent on photosynthetic and chemosynthetic organisms are called heterotrophs. 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, both processes take place through a different sequence of chemical reactions and in different cellular compartments. Cellulose as polymer of β-D-glucose Cellulose in 3D Cellulose (C6H10O5)n is a polysaccharide of beta-glucose. ... Some common lipids. ... This article is about the class of chemicals. ... Cellular respiration was discovered by mad scientist Mr. ... For other uses, see Animal (disambiguation). ... Food chains, food webs and/or food networks describe the feeding relationships between species to another within an ecosystem. ... Chemosynthesis is the biological conversion of 1 or more carbon molecules (usually carbon dioxide or methane) and nutrients into organic matter using the oxidation of inorganic molecules (e. ... Flowchart to determine if a species is autotroph, heterotroph, or a subtype A heterotroph (Greek heterone = (an)other and trophe = nutrition) is an organism that requires organic substrates to get its carbon for growth and development. ...


Plants absorb light primarily using the pigment chlorophyll, which is the reason that most plants have a green color. The function of chlorophyll is often supported by other accessory pigments such as carotenes and xanthophylls. Both chlorophyll and accessory pigments are contained in organelles (compartments within the cell) called Chloroplasts. Although all cells in the green parts of a plant have chloroplasts, most of the energy is captured in the leaves. 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. 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. The transparent epidermis layer allows light to pass through to the palisade mesophyll cells where most of the photosynthesis takes place. Natural Ultramarine pigment in powdered form. ... Chlorophyll is a green pigment found in most plants, algae, and cyanobacteria. ... An accessory pigment is a pigment other than chlorophyll found in plants, such as a carotenoid, that serves the function of absorbing light energy, and transfering it to chlorophyll. ... β-Carotene represented by a 3-dimensional stick diagram Carotene is responsible for the orange colour of the carrots and many other fruits and vegetables. ... This article or section does not cite its references or sources. ... Schematic of typical animal cell, showing subcellular components. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. ... Look up foliage in Wiktionary, the free dictionary. ... This article is about the leaf, a plant organ. ... candle wax This page is about the substance. ... Plant cuticles are a protective waxy covering produced only by the epidermal cells (Kolattukudy, 1996) of leaves, young shoots and all other aerial plant organs. ... Vaporization redirects here. ... For other uses, see Ultraviolet (disambiguation). ... This article is about the colour. ... For other uses, see Light (disambiguation). ... For other uses, see Heat (disambiguation) In physics, heat, symbolized by Q, is energy transferred from one body or system to another due to a difference in temperature. ... Look up foliage in Wiktionary, the free dictionary. ... Look up foliage in Wiktionary, the free dictionary. ...


Plants use up to 90% of the light that strikes them, whereas commercial solar panels use less than 30%. This is achieved by groups of chlorophyll molecules spending a long time in a superposition of states.[4] Quantum superposition is the application of the superposition principle to quantum mechanics. ...


In algae and bacteria

Algae come in multiple forms from multicellular organisms like kelp, to microscopic, single-cell organisms. 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. All algae produce oxygen, and many are autotrophic. 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.[5] Families Alariaceae Chordaceae Laminariaceae Lessoniaceae Phyllariaceae Pseudochordaceae Percentages are relative to US recommendations for adults. ... Microscopy is any technique for producing visible images of structures or details too small to otherwise be seen by the human eye, using a microscope or other magnification tool. ... A cluster of Escherichia coli bacteria magnified 10,000 times. ... An accessory pigment is a pigment other than chlorophyll found in plants, such as a carotenoid, that serves the function of absorbing light energy, and transfering it to chlorophyll. ... Phycocyanin is a pigment that is blue and is readily found in blue-green algae. ... β-Carotene represented by a 3-dimensional stick diagram Carotene is responsible for the orange colour of the carrots and many other fruits and vegetables. ... This article or section does not cite its references or sources. ... Divisions Chlorophyta Charophyta Green algae are microscopic protists; found in all aquatic environments, including marine, freshwater and brackish water. ... Phycoerythrin is a red protein from the light-harvesting phycobiliproteins family, isolated from red, blue-green, and crytomonad algae. ... Possible classes Florideophyceae Bangiophyceae Cyanidiophyceae The red algae (Rhodophyta, IPA: , from Greek: (rhodon) = rose + (phyton) = plant, thus red plant) are a large group, about 5,000–6,000 species [1] of mostly multicellular, marine algae, including many notable seaweeds. ... Green (from chlorophyll) fronds of a maidenhair fern: a photoautotroph Flowchart to determine if a species is autotroph, heterotroph, or a subtype An autotroph (from the Greek autos = self and trophe = nutrition) is an organism that produces complex organic compounds from simple inorganic molecules and an external source of energy... Some of the biodiversity of a coral reef, in this case the Great Barrier Reef, Australia. ... In biology, mutualism is an interaction between two or more species, where both species derive benefit. ... Zooxanthellae are golden-brown intracellular endosymbionts of various marine animals and protozoa, especially anthozoans. ... Anatomy of a coral polyp. ...


Photosynthetic bacteria do not have chloroplasts (or any membrane-bound organelles). 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. In fact, chloroplasts are now considered to have evolved from an endosymbiotic bacterium, which was also an ancestor of and later gave rise to cyanobacterium. The other photosynthetic bacteria have a variety of different pigments, called bacteriochlorophylls, and do not produce oxygen. Some bacteria, such as Chromatium, oxidize hydrogen sulfide instead of water for photosynthesis, producing sulfur as waste. Schematic of typical animal cell, showing subcellular components. ... Orders The taxonomy is currently under revision. ... A thylakoid is a phospholipid bilayer membrane internal to chloroplasts. ... This article is about evolution in biology. ... An endosymbiont (also known as intracellular symbiont) is any organism that lives within cells of another organism, i. ... Bacteriochlorophylls are photosynthetic pigments that occur in various bacteria. ... Type species Chromatium okenii Species C. okenii The Chromatium are a Gram-negative bacterium found in water. ... Hydrogen sulfide (hydrogen sulphide in British English) is the chemical compound with the formula H2S. This colorless, toxic and flammable gas is responsible for the foul odor of rotten eggs and flatulence. ... This article is about the chemical element. ...


Evolution

Plant cells with visible chloroplasts.
Plant cells with visible chloroplasts.

The ability to convert light energy to chemical energy confers a significant evolutionary advantage to living organisms. 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. Green and purple sulfur bacteria are thought to have used hydrogen and sulfur as an electron donor. Green nonsulfur bacteria used various amino and other organic acids. 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.[citation needed] Image File history File linksMetadata No higher resolution available. ... For other uses, see Natural selection (disambiguation). ... Green sulfur bacteria - Wikipedia, the free encyclopedia /**/ @import /skins-1. ... Families Chromatiaceae Ectothiorhodospiraceae Halothiobacillaceae The purple sulfur bacteria are a group of Proteobacteria capable of photosynthesis, collectively referred to as purple bacteria. ... Orders / Families / Genera Order Chloroflexales     Family Chloroflexaceae      Chloroflexus      Chloronema      Heliothrix      Roseiflexus    Family Oscillochloridaceae      Oscillochloris Order Herpetosiphonales      Herpetosiphon Order Dehalococcoidetes       Dehalococcoides The Chloroflexi are a group of bacteria that produce energy through photosynthesis. ... Purple bacteria or purple photosynthetic bacteria are proteobacteria that are phototrophic, i. ... An electron donor is a compound that gives up or donates an electron during cellular respiration, resulting in the release of energy. ... This article is about the chemistry of hydrogen. ... This article is about the chemical element. ... This article is about the class of chemicals. ... An organic acid is an organic compound that is an acid. ... A reducing environment is one chacterized by little or no free oxygen (dissolved or as a gas). ... Geological time put in a diagram called a geological clock, showing the relative lengths of the eons of the Earths history. ...


Fossils of what are thought to be filamentous photosynthetic organisms have been dated at 3.4 billion years old.[6] Filaments surrounding a solar flare, caused by the interaction of the plasma in the Suns atmopshere with its magnetic field. ...


Oxygen in the atmosphere exists due to the evolution of oxygenic photosynthesis, sometimes referred to as the oxygen catastrophe. Geological evidence suggests that oxygenic photosynthesis, such as that in cyanobacteria, became important during the Paleoproterozoic era around 2 billion years ago. 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. This article is about the chemical element and its most stable form, or dioxygen. ... Air redirects here. ... 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 era. ... Orders The taxonomy is currently under revision. ... The Paleoproterozoic is the first of the three sub-divisions of the Proterozoic occurring between 2500 to 1600 million years ago. ... ed|other uses|reduction}} Illustration of a redox reaction Redox (shorthand for reduction/oxidation reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed. ... In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ... In the process of photosynthesis, light is absorbed by a photosystem (ancient Greek: phos = light and systema = assembly) to begin an energy-producing reaction. ...


Origin of chloroplasts

In plants the process of photosynthesis occurs in organelles called chloroplasts. Chloroplasts have many similarities with photosynthetic bacteria including a circular chromosome, prokaryotic-type ribosomes, and similar proteins in the photosynthetic reaction center. Schematic of typical animal cell, showing subcellular components. ... Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. ... Orders The taxonomy is currently under revision. ... A scheme of a condensed (metaphase) chromosome. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ...


The endosymbiotic theory suggests that photosynthetic bacteria were acquired (by endocytosis or gene fusion) by early eukaryotic cells to form the first plant cells. 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 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. Both chloroplasts and mitochondria actually have their own DNA, separate from the nuclear DNA of their animal or plant host cells. The endosymbiotic theory concerns the origins of mitochondria and plastids (e. ... Endocytosis (IPA: ) is a process whereby cells absorb material (molecules such as proteins) from the outside by engulfing it with their cell membrane. ... Gene-Fusion is a 26 part animated television series produced by Banjax based on an original comic from Beckett Entertainment. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Chromalveolata Protista Alternative phylogeny Unikonta Opisthokonta Metazoa Choanozoa Eumycota Amoebozoa Bikonta Apusozoa Cabozoa Rhizaria Excavata Corticata Archaeplastida Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms whose cells are organized into complex structures by internal membranes and a cytoskeleton. ... For other uses, see Plant (disambiguation). ... In cell biology, a mitochondrion is an organelle found in the cells of most eukaryotes. ... Species Rickettsia felis Rickettsia prowazekii Rickettsia rickettsii Rickettsia typhi Rickettsia conorii Rickettsia africae etc. ...


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. However, they do not transfer these chloroplasts to the next generations. Classes Caudofoveata Aplacophora Polyplacophora Monoplacophora Bivalvia Scaphopoda Gastropoda Cephalopoda † Rostroconchia † Helcionelloida † ?Bellerophontida The molluscs (British spelling) or mollusks (American spelling) are members of the very large and diverse phylum Mollusca. ... Binomial name Elysia viridis Elysia viridis is a sea slug gastropod mollusc that lives in a subcellular endosymbiotic relationship with chloroplasts of the alga Codium fragile. ... Binomial name Elysia chlorotica Elysia chlorotica Gould is a littoral sea slug that lives in a subcellular endosymbiotic relationship with chloroplasts of the marine heterokont alga Vaucheria litorea C. Agardh, which provide their host with the products of photosynthesis. ... For other uses, see Symbiosis (disambiguation). ...


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. 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. 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. 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. 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.[7] Orders The taxonomy is currently under revision. ... The Archean is a geologic eon; it is a somewhat antiquated term for the time span between 2500 million years before the present and 3800 million years before the present. ... This article is about evolution in biology. ... Orders The taxonomy is currently under revision. ... The Proterozoic (IPA: ) 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 nitrogen compounds (such as, notably, ammonia, nitrate and nitrogen dioxide)[1] useful for other chemical processes. ... Divisions Chlorophyta Charophyta Green algae are microscopic protists; found in all aquatic environments, including marine, freshwater and brackish water. ... The Proterozoic (IPA: ) 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. ...


Molecular production

Light-dependent reactions of photosynthesis at the thylakoid membrane

Image File history File links Size of this preview: 800 × 456 pixel Image in higher resolution (905 × 516 pixel, file size: 82 KB, MIME type: image/png) Light-dependent reactions of photosynthesis at the thylakoid membrane. ... Image File history File links Size of this preview: 800 × 456 pixel Image in higher resolution (905 × 516 pixel, file size: 82 KB, MIME type: image/png) Light-dependent reactions of photosynthesis at the thylakoid membrane. ...

Light to chemical energy

The light energy is converted to chemical energy using the light-dependent reactions. This chemical energy production is more than 90% efficient with only 5-8% of the energy transferred thermally. The products of the light-dependent reactions are ATP from photophosphorylation and NADPH from photoreduction. Both are then utilized as an energy source for the light-independent reactions. Light-dependent reactions of photosynthesis at the thylakoid membrane The initial stage of the photosynthetic system is the light-dependent reaction, which converts solar energy into chemical energy. ... Light-dependent reactions of photosynthesis at the thylakoid membrane The initial stage of the photosynthetic system is the light-dependent reaction, which converts solar energy into chemical energy. ... Light-dependent reactions of photosynthesis at the thylakoid membrane The initial stage of the photosynthetic system is the light-dependent reaction, which converts solar energy into chemical energy. ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ... The production of ATP using the energy of sunlight is called photophosphorylation. ... Nicotinamide adenine dinucleotide (NAD+) Nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) are two important coenzymes found in cells. ... Overview of the Calvin cycle and carbon fixation In photosynthesis, the light-independent reactions, also somewhat misleadingly called the dark reactions (they dont require darkness, but they do require the products of the light reactions), are chemical reactions that convert carbon dioxide and other compounds into glucose. ...


Not all wavelengths of light can support photosynthesis. The photosynthetic action spectrum depends on the type of accessory pigments present. For example, in green plants, the action spectrum resembles the absorption spectrum for chlorophylls and carotenoids with peaks for violet-blue and red light. 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. 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. For other uses, see Wavelength (disambiguation). ... An accessory pigment is a pigment other than chlorophyll found in plants, such as a carotenoid, that serves the function of absorbing light energy, and transfering it to chlorophyll. ... An action spectrum is the rate of a physiological activity plotted against wavelength of light. ... A materials 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. ... The orange ring surrounding Grand Prismatic Spring is due to carotenoid molecules, produced by huge mats of algae and bacteria. ... Phycobilins are the chromophores of phycobiliproteins (photosynthetic pigments) found in cyanobacteria and in the chloroplasts of red algae, glaucophytes and some cryptomonads (though not in green algae and higher plants). ...


Z scheme
A Photosystem: A light-harvesting cluster of photosynthetic pigments present in the thylakoid membrane of chloroplasts.
A Photosystem: A light-harvesting cluster of photosynthetic pigments present in the thylakoid membrane of chloroplasts.
The "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 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). 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. 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 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. The electron enters the Photosystem I molecule. The electron is excited due to the light absorbed by the photosystem. A second electron carrier accepts the electron, which again is passed down lowering energies of electron acceptors. 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. Image File history File links Photosystems. ... Image File history File links Photosystems. ... Download high resolution version (905x281, 36 KB)Z-scheme File links The following pages link to this file: Light-dependent reaction Categories: GFDL images ... Download high resolution version (905x281, 36 KB)Z-scheme File links The following pages link to this file: Light-dependent reaction Categories: GFDL images ... Light-dependent reactions of photosynthesis at the thylakoid membrane The initial stage of the photosynthetic system is the light-dependent reaction, which converts solar energy into chemical energy. ... A thylakoid is a phospholipid bilayer membrane internal to chloroplasts. ... Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. ... In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ... The antenna complex is an array of chlorophyll molecules embedded in the thylakoid membrane that transfer energy to a pair of chlorophyll a molecules at the reaction center of a photosystem. ... REDIRECT [[In the process of photosynthesis, light is absorbed by a photosystem (ancient Greek: phos = light and systema = assembly) to begin an energy-producing reaction. ... Chlorophyll is a green pigment found in most plants, algae, and cyanobacteria. ... Chlorophyll gives leaves their green colour Chlorophyll is a green photosynthetic pigment found in plants, algae, and cyanobacteria. ... 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 acceptor. ... The electron transfer chain (also called the electron transport chain, ETC, e-train, or simply electron transport), is any series of protein complexes and lipid-soluble messengers that convert the reductive potential of energized electrons into a cross-membrane proton gradient. ... Electrochemical potential is a thermodynamic measure that reflects energy from entropy and electrostatics and is typically invoked in molecular processes that involve diffusion. ... An ATP synthase (EC 3. ... Nicotinamide adenine dinucleotide (NAD+) Nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) are two important coenzymes found in cells. ... ed|other uses|reduction}} Illustration of a redox reaction Redox (shorthand for reduction/oxidation reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed. ... An electron acceptor is a chemical entity that accepts electrons transferred to it from another compound. ...


Water photolysis

The NADPH is the main reducing agent in chloroplasts, providing a source of energetic electrons to other reactions. 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. 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. 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. 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. Photosystem II is the only known biological enzyme that carries out this oxidation of water. 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. Photodissociation is the breakup of molecules caused by exposure to 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) that reduces another species. ... Plastocyanin is a single strand protein of the thylakoid membrane, (molecular weight 10,500), that plays an integral part in photosynthesis. ... This article is about the chemical element and its most stable form, or dioxygen. ... This article is about the chemistry of hydrogen. ... Tyrosine (from the Greek tyros, meaning cheese, as it was first discovered in 1846 by German chemist Justus von Liebig in the protein casein from cheese[1][2]), 4-hydroxyphenylalanine, or 2-amino-3(4-hydroxyphenyl)-propanoic acid, is one of the 20 amino acids that are used by cells... Catalyst redirects here. ... General Name, symbol, number manganese, Mn, 25 Chemical series transition metals Group, period, block 7, 4, d Appearance silvery metallic Standard atomic weight 54. ... Oxygen evolution is the process of generating molecular oxygen through chemical reaction. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Cellular respiration was discovered by mad scientist Mr. ...


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%[8].


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. Results of the study are presented in the April 12, 2007 issue of the journal Nature.[9] The United States Department of Energy (DOE) is a Cabinet-level department of the United States government responsible for energy policy and nuclear safety. ... The Ernest Orlando Lawrence Berkeley National Laboratory (LBNL), formerly the Berkeley Radiation Laboratory and usually shortened to Berkeley Lab or LBL, is a U.S. Department of Energy (DOE) national laboratory conducting unclassified scientific research. ... The University of California, Berkeley (also known as Cal, UC Berkeley, UCB, or simply Berkeley) is a prestigious, public, coeducational university situated in the foothills of Berkeley, California to the east of San Francisco Bay, overlooking the Golden Gate and its bridge. ... Quantum coherence refers to the condition of a quantum system whose constituents are in-phase. ... Nature is a prominent scientific journal, first published on 4 November 1869. ...


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.
  • 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. Consequently, the source of oxygen during photosynthesis is water, not carbon dioxide.

Orders The taxonomy is currently under revision. ...

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. Aside from the cyanobacteria, bacteria only have one photosystem and use reducing agents other than water. 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 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. ... Orders The taxonomy is currently under revision. ... Formally, sulfide is the dianion, S2−, which exists in strongly alkaline aqueous solutions formed from H2S or alkali metal salts such as Li2S, Na2S, and K2S. Sulfide is exceptionally basic and, with a pKa > 14, it does not exist in appreciable concentrations even in highly alkaline water. ... This article is about the chemistry of hydrogen. ...


Others, such as the halophiles (an Archaea), produced so-called purple membranes where the bacteriorhodopsin could harvest light and produce energy. 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. Halophiles are extremophiles that thrive in environments with very high concentrations of salt (at least 2 M, approximately ten times the salt level of ocean water). ... Phyla Crenarchaeota Euryarchaeota Korarchaeota Nanoarchaeota ARMAN The Archaea (pronounced ) are a group of prokaryotic and single-celled microorganisms. ... Bacteriorhodopsin is a photosynthetic pigment used by archaea, most notably halobacteria. ... Chemiosmosis is the diffusion of ions across a membrane. ...

Overview of the Calvin cycle and carbon fixation
Overview of the Calvin cycle and carbon fixation

Image File history File links Download high resolution version (856x742, 51 KB)This image was copied from wikipedia:en. ... Image File history File links Download high resolution version (856x742, 51 KB)This image was copied from wikipedia:en. ...

Carbon fixation

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). GP, in the presence of ATP and NADPH from the light-dependent stages, is reduced to glyceraldehyde 3-phosphate (G3P). This product is also referred to as 3-phosphoglyceraldehyde (PGAL) or even as triose phosphate. Triose is a 3-carbon sugar (see carbohydrates). 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 1 out of 6 molecules of the triose phosphates not "recycled" often condense to form hexose phosphates, which ultimately yield sucrose, starch and cellulose. 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. Carbon fixation is a process found in autotrophs, usually driven by photosynthesis, whereby carbon dioxide is changed into organic materials. ... Overview of the Calvin cycle and carbon fixation In photosynthesis, the light-independent reactions, also somewhat misleadingly called the dark reactions (they dont require darkness, but they do require the products of the light reactions), are chemical reactions that convert carbon dioxide and other compounds into glucose. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... Categories: Stub | Photosynthesis ... Glycerate 3-phosphate (GP) or 3-phosphoglycerate (3PG). ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ... Nicotinamide adenine dinucleotide (NAD+) Nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) are two important coenzymes found in cells. ... G3P (structure) Glyceraldehyde 3-phosphate (G3P) is an intermediate in both glycolysis and gluconeogenesis. ... 3-phosphoglyceraldehyde or PGAL is 3-carbon glyceraldehyde 3-phosphate. ... A triose is a monosaccharide containing three carbon atoms. ... Lactose is a disaccharide found in milk. ... The Calvin cycle (also known as Calvin-Benson cycle) is a series of biochemical reactions taking place in the chloroplasts of photosynthetic organisms. ... A hexose is a monosaccharide with six carbon atoms having the chemical formula C6H12O6. ... Flash point N/A Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox disclaimer and references Sucrose (common name: table sugar, also called saccharose) is a disaccharide (glucose + fructose) with the molecular formula C12H22O11. ... Starch (CAS# 9005-25-8, chemical formula (C6H10O5)n,[1]) is a mixture of amylose and amylopectin (usually in 20:80 or 30:70 ratios). ... Cellulose as polymer of β-D-glucose Cellulose in 3D Cellulose (C6H10O5)n is a polysaccharide of beta-glucose. ... Structure of the coenzyme adenosine triphosphate, a central intermediate in energy metabolism. ... In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... Figure 1: Basic lipid structure. ...


C4, C3 and CAM

In hot and dry conditions, plants will close their stomata to prevent loss of water. Under these conditions, oxygen gas, produced by the light reactions of photosynthesis, will concentrate in the leaves causing photorespiration to occur. Some plants have evolved mechanisms to increase the CO2 concentration in the leaves under these conditions. Image File history File links HatchSlackpathway. ... Image File history File links HatchSlackpathway. ... Overview of C4 carbon fixation C4 carbon fixation is one of three methods, along with C3 and CAM photosynthesis, used by land plants to fix carbon dioxide (binding the gaseous molecules to dissolved compounds inside the plant) for sugar production through photosynthesis. ... This is not about surgically created bowel openings; see stoma (medicine) In botany, a stoma (also stomate; plural stomata) is a tiny opening or pore, found mostly on the undersurface of a plant leaf, and used for gas exchange. ... Photorespiration refers to the alternate pathway for production of Glyceraldehyde 3-phosphate (G3P) by Rubisco, the main enzyme of the light-independent reactions of photosynthesis (also known as the Calvin cycle or the Primary Carbon Reduction (PCR) cycle). ... This article is about evolution in biology. ...


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. 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. 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. Overview of C4 carbon fixation C4 carbon fixation is one of three methods, along with C3 and CAM photosynthesis, used by land plants to fix carbon dioxide (binding the gaseous molecules to dissolved compounds inside the plant) for sugar production through photosynthesis. ... PEP Carboxylase is the enzyme responsible for the primary fixation of carbon dioxide in c4 plants. ... Name Phosphoenolpyruvate; Phosphoenolpyruvic acid; PEP Formula C3H5O6P Mass 167. ... Oxaloacetic acid is an organic compound with the chemical formula HO2CC(O)CH2CO2H. It also has other names (see Table) and its conjugate base is called oxaloacetate. ... C3 carbon fixation is a pathway for carbon fixation in photosynthesis. ... Glycerate 3-phosphate (GP) or 3-phosphoglycerate (3PG). ...


Xerophytes such as cacti and most succulents also can use PEP Carboxylase to capture carbon dioxide in a process called Crassulacean acid metabolism (CAM). 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). 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. 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. A xerophyte is an organism that has adaptations to enable it to get through, or even thrive, in areas with very little free moisture. ... This article is about the desert plant. ... Sempervivum heuffelii, type from Romania, in cultivation, a member of the Crassulaceae, storing water in its thick leaves. ... Crassulacean acid metabolism (CAM) is a carbon fixation pathway in some photosynthetic plants. ... Malate redirects here. ... Name Phosphoenolpyruvate; Phosphoenolpyruvic acid; PEP Formula C3H5O6P Mass 167. ... This article is about the leaf, a plant organ. ...


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. 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. Jan van Helmont (1580-1644) was a Belgian scientist, often referred to as the father of photosynthesis. He conducted a simple experiment: Using a potted plant, he carefully measured the mass of the soil of the plant in the beginning of the experiment. ... For other uses, see Mass (disambiguation). ... For the eco-industrial use of the term, which includes dead material used for biofuels, see biomass An Antarctic krill, whose species comprises roughly 0. ...


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. 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. Priestley by Ellen Sharples (1794)[1] Joseph Priestley (March 13, 1733 (old style) – February 8, 1804) was an eighteenth-century British natural philosopher, Dissenting clergyman, political theorist, theologian, and educator. ...


In 1778, Jan Ingenhousz, court physician to the Austrian Empress, repeated Priestley's experiments. 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. Jan Ingenhousz or Ingen-Housz (December 8, 1730 - September 7, 1799) was a Dutch-born British physiologist, botanist and physicist. ...


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. 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. Thus the basic reaction by which photosynthesis is used to produce food (such as glucose) was outlined. Jean Senebier (May 6, 1742 - July 22, 1809) was a Swiss pastor who wrote many works on vegetable physiology. ... Nicolas-Théodore de Saussure (14 October 1767 - 18 April 1845) was a Switzerland chemist and student of plant physiology who made seminal advances in phytochemistry. ...


Cornelis Van Niel made key discoveries explaining the chemistry of photosynthesis. 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 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. ... Families Chromatiaceae Ectothiorhodospiraceae Halothiobacillaceae The purple sulfur bacteria are a group of Proteobacteria capable of photosynthesis, collectively referred to as purple bacteria. ... ed|other uses|reduction}} Illustration of a redox reaction Redox (shorthand for reduction/oxidation reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed. ...


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. 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. The Hill reaction is as follows: Dr. Robert (Robin) Hill (April 2, 1899 – March 15, 1991), was a British plant biochemist who, in 1939, demonstrated the ‘Hill reaction’ of photosynthesis, proving that oxygen is evolved during the light requiring steps of photosynthesis. ... Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. ... General Name, symbol, number iron, Fe, 26 Chemical series transition metals Group, period, block 8, 4, d Appearance lustrous metallic with a grayish tinge Standard atomic weight 55. ... An oxalate (called also: ethanedioate) is a salt or ester of oxalic acid. ... The ferricyanide ion is Fe(CN)63-. Its systematic name is hexacyanoferrate(III) ion, but its old name is most common. ... Quinone is generally defined as an aromatic beneze molecule containing a double ketone functional group. ...

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.


Samuel Ruben and Martin Kamen used radioactive isotopes to determine that the oxygen liberated in photosynthesis came from the water. Sam Ruben, with Martin Kamen, co discoverer of isotope Carbon-14. ... Martin David Kamen (1913 - 2002), was co-discoverer (with Sam Ruben) of the isotope carbon-14 on February 27th, 1940, at the University of California Radiation Laboratory, Berkeley. ...


Melvin Calvin and Andrew Benson, along with James Bassham, elucidated the path of carbon assimilation (the photosynthetic carbon reduction cycle) in plants. The carbon reduction cycle is known as the Calvin cycle, which inappropriately ignores the contribution of Bassham and Benson. 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. Melvin Calvin he had fun in bed Melvin Calvin (April 8, 1911 – January 8, 1997) was a chemist most famed for discovering the Calvin cycle (along with Andrew Benson), for which he was awarded the 1961 Nobel Prize in Chemistry. ... Andrew Benson was a scientist who, along with Melvin Calvin and James Bassham, elucidated the path of carbon assimilation (the photosynthetic carbon reduction cycle) in plants. ... Overview of the Calvin cycle and carbon fixation The Calvin cycle (or Calvin-Benson cycle or carbon fixation) is a series of biochemical reactions that takes place in the stroma of chloroplasts in photosynthetic organisms. ...


A Nobel Prize winning scientist, Rudolph A. Marcus, was able to discover the function and significance of the electron transport chain. The Nobel Prize (Swedish: ) was established in Alfred Nobels will in 1895, and it was first awarded in Physics, Chemistry, Physiology or Medicine, Literature, and Peace in 1901. ... Rudolph A. Marcus in 2005 Rudolph Rudy Arthur Marcus (born July 21, 1923) 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:

Irradiance, radiant emittance, and radiant exitance are radiometry terms for the power of electromagnetic radiation at a surface, per unit area. ... For other uses, see Wavelength (disambiguation). ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... For other uses, see Concentration (disambiguation). ... For other uses, see Temperature (disambiguation). ...

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 area. ...

  • 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. 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. Second, Blackman's experiments illustrate the concept of limiting factors. 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. This article is about the concept. ... Photochemistry is the study of the interaction of light and chemicals. ... For other uses, see Temperature (disambiguation). ... Light-dependent reactions of photosynthesis at the thylakoid membrane The initial stage of the photosynthetic system is the light-dependent reaction, which converts solar energy into chemical energy. ... Overview of the Calvin cycle and carbon fixation In photosynthesis, the light-independent reactions, also somewhat misleadingly called the dark reactions (they dont require darkness, but they do require the products of the light reactions), are chemical reactions that convert carbon dioxide and other compounds into glucose. ... In biology, agricultural science, physiology, and ecology, a limiting factor is one that controls a process, such as organism growth or species population size or distribution. ... A computer generated 3D view of a phycobilisome showing Phycoerythrin subunits in red, Phycocyanin subunits in dark blue and Allophycocyanin subunits in light blue. ...


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. RuBisCO, the enzyme that captures carbon dioxide in the light-independent reactions, has a binding affinity for both carbon dioxide and oxygen. When the concentration of carbon dioxide is high, RuBisCO will fix carbon dioxide. 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. Overview of the Calvin cycle and carbon fixation In photosynthesis, the light-independent reactions, also somewhat misleadingly called the dark reactions (they dont require darkness, but they do require the products of the light reactions), are chemical reactions that convert carbon dioxide and other compounds into glucose. ... Ribulose-1,5-bisphosphate carboxylase/oxygenase, most commonly known by the shorter name RuBisCO, is an enzyme (EC 4. ... Carbon fixation is a process found in autotrophs, usually driven by photosynthesis, whereby carbon dioxide is changed into organic materials. ... Photorespiration refers to the alternate pathway for production of Glyceraldehyde 3-phosphate (G3P) by Rubisco, the main enzyme of the light-independent reactions of photosynthesis (also known as the Calvin cycle or the Primary Carbon Reduction (PCR) cycle). ...


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.
  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. Glycerate 3-phosphate (GP) or 3-phosphoglycerate (3PG). ... The Calvin cycle (also known as Calvin-Benson cycle) is a series of biochemical reactions taking place in the chloroplasts of photosynthetic organisms. ... Photorespiration refers to the alternate pathway for production of Glyceraldehyde 3-phosphate (G3P) by Rubisco, the main enzyme of the light-independent reactions of photosynthesis (also known as the Calvin cycle or the Primary Carbon Reduction (PCR) cycle). ...


See also

Artificial photosynthesis is a research field that attempts to replicate the natural process of photosynthesis, converting sunlight, water and carbon dioxide into carbohydrates and oxygen. ... The Calvin cycle (also known as Calvin-Benson cycle) is a series of biochemical reactions taking place in the chloroplasts of photosynthetic organisms. ... Carbon fixation is a process found in autotrophs, usually driven by photosynthesis, whereby carbon dioxide is changed into organic materials. ... Cellular respiration was discovered by mad scientist Mr. ... Light-dependent reactions of photosynthesis at the thylakoid membrane The initial stage of the photosynthetic system is the light-dependent reaction, which converts solar energy into chemical energy. ... Photoinhibition is the process by which the capacity for photosynthesis in plants is reduced in strong light (above the light saturation point). ... In the process of photosynthesis, light is absorbed by a photosystem (ancient Greek: phos = light and systema = assembly) to begin an energy-producing reaction. ... PAR is the range of light, 400-700nm that can be photosynthesized by plants. ... Quantum biology is the scientific study of biological processes in terms of quantum mechanics. ... Red edge refers to the region of rapid change in reflectance of chlorophyll in the near infrared range. ...

Notes

  1. ^ a b D.A. Bryant & N.-U. Frigaard (Nov 2006). "Prokaryotic photosynthesis and phototrophy illuminated". Trends Microbiol. 14 (11): 488. doi:doi:10.1016/j.tim.2006.09.001. 
  2. ^ Brown, LeMay, Burslen, Chemistry The Central Science, ISBN 0-13-048450-4, p. 958
  3. ^ a b Raven, Peter H.; Ray F. Evert, Susan E. Eichhorn (2005). Biology of Plants, 7th Edition. New York: W.H. Freeman and Company Publishers, 124-127. ISBN 0-7167-1007-2. 
  4. ^ Quantum capture, in Science News vol 171, p. 229
  5. ^ Natural History Museum. AlgaeVision. Retrieved on 2007-06-13.
  6. ^ New Scientist, 19 Aug., 2006
  7. ^ Herrero A and Flores E (editor). (2008). The Cyanobacteria: Molecular Biology, Genomics and Evolution, 1st ed., Caister Academic Press. ISBN 978-1-904455-15-8 . 
  8. ^ University of Prince Edwards Island, Canada. "Photosynthesis Outline". Accessed 2007-Nov-25.
  9. ^ Lawrence Berkeley National Lab. "Quantum secrets of photosynthesis revealed", physorg.com, April 12, 2007. Accessed April 13, 2007.

A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st century. ... is the 164th day of the year (165th in leap years) in the Gregorian calendar. ...

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

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Pinguicula grandiflora commonly known as a Butterwort Example of a cross section of a stem [1] Botany is the scientific study of plant life. ... Ethnobotany is the study of the relationship between plants and people: Fromethno - study of people and botany - study of plants. ... Paleobotany (from the Greek words paleon = old and botanikos = of herbs) is the branch of paleontology dealing with the recovery and identification of plant remains from geological contexts, and their use in the reconstruction of past environments and the history of life. ... Plant anatomy or phytotomy is the general term for the study of the structure of plants. ... For the journal, see Ecology (journal). ... Evolutionary developmental biology (evo-devo) refers to the study of developmental programs and patterns from an evolutionary perspective. ... Plant anatomy or phytotomy is the general term for the study of the structure of plants. ... A germination rate experiment Plant physiology is a subdiscipline of botany concerned with the function, or physiology, of plants. ... Download high resolution version (454x765, 178 KB)Coconut Palm on Martinique. ... For other uses, see Plant (disambiguation). ... Plant evolution is an aspect of the study of biological evolution, involving predominantly the evolution of plants suited to live on land, the greening of the various land masses by the filling of their niches with land plants, and the diversification of the groups of land plants. ... Osborne (talk) 20:17, 5 December 2007 (UTC):For the programming language, see algae (programming language) Laurencia, a marine red alga from Hawaii. ... The bryophytes are those embryophytes (land plants) that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. ... Classes Marattiopsida Osmundopsida Gleicheniopsida Pteridopsida A fern, or pteridophyte, is any one of a group of some twenty thousand species of plants classified in the Division Pteridophyta, formerly known as Filicophyta. ... Divisions Pinophyta (or Coniferophyta) - Conifers Ginkgophyta - Ginkgo Cycadophyta - Cycads Gnetophyta - Gnetum, Ephedra, Welwitschia The gymnosperms (Gymnospermae) are a group of spermatophyte seed-bearing plants with ovules on the edge or blade of an open sporophyll, the sporophylls usually arranged in cone-like structures. ... Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants or angiosperms are the most widespread group of land plants. ... For other uses, see Flower (disambiguation). ... For other uses, see Fruit (disambiguation). ... Look up foliage in Wiktionary, the free dictionary. ... Tunica-Corpus model of the apical meristem. ... For other uses, see Root (disambiguation). ... Stem showing internode and nodes plus leaf petiole and new stem rising from node. ... Stoma of a leaf under a microscope. ... Cross section of celery stalk, showing vascular bundles, which include both phloem and xylem. ... For other uses, see Wood (disambiguation). ... For the scientific journal see The Plant Cell. ... Plant cells separated by transparent cell walls. ... Chlorophyll is a green pigment found in most plants, algae, and cyanobacteria. ... Chloroplasts are organelles found in plant cells and eukaryotic algae that conduct photosynthesis. ... Plant hormones (also known as plant growth regulators (PGRs) and phytohormones) are chemicals that regulate a plants growth. ... Plant cells with visible chloroplasts. ... Transpiration is the evaporation of excess water from aerial parts and of plants, especially leaves but also stems, flowers and fruits. ... Sporic or diplohaplontic life cycle. ... In plants that undergo alternation of generations, a gametophyte is the structure, or phase of life, that contains only half of the total complement of chromosomes: The sporophyte produces spores, in a process called meiosis. ... Close-up of an Echinopsis spachiana flower, showing both carpels and stamen, making it a complete flower. ... SEM image of pollen grains from a variety of common plants: sunflower (Helianthus annuus), morning glory (Ipomoea purpurea), prairie hollyhock (Sidalcea malviflora), oriental lily (Lilium auratum), evening primrose (Oenothera fruticosa), and castor bean (Ricinus communis). ... Carpenter bee with pollen collected from Night-blooming cereus Pollination is an important step in the reproduction of seed plants: the transfer of pollen grains (male gametes) to the plant carpel, the structure that contains the ovule (female gamete). ... A ripe red jalapeño cut open to show the seeds For other uses, see Seed (disambiguation). ... This article or section is in need of attention from an expert on the subject. ... Young sporophytes of the common moss Tortula muralis. ... Plant taxonomy is the science that finds, describes, classifies and names plants. ... A botanical name is a formal name conforming to the ICBN. As with its zoological and bacterial equivalents it may also be called a scientific name. Botanical names may be in one part (genus and above), two parts (species) or three parts (below the rank of species). ... Botanical nomenclature Plants are given formal names, governed by the ICBN. Within the limits set by the ICBN there is a separate set of rules, the ICNCP, for those plants in cultivation that require separate recognition, so-called cultivars. ... In Botany, a herbarium is a collection of preserved plants or plant parts, mainly in a dried form. ... The International Association for Plant Taxonomy (IAPT) is devoted to plant systematics, taxonomy and nomenclature. ... 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  Results from FactBites:
 
BBC - GCSE Bitesize - Biology | Green plants | Photosynthesis (309 words)
gaseous compound of carbon and oxygen which is a by-product of respiration, and which is needed by plants for photosynthesis
Plants can turn the glucose produced in photosynthesis into starch for storage, and turn it back into glucose when it is needed for respiration.
It is needed for photosynthesis, which changes light energy into chemical energy.
  More results at FactBites »

 
 

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