Photosynthesis

Photosynthesis - Overview

In biology, photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can later be released to fuel the organisms' activities. This chemical energy is stored in carbohydrate molecules, such as sugars, which are synthesized from carbon dioxide and water – hence the name photosynthesis, from Greek ???, "ph?s", "light", and ????????, "synthesis", meaning "putting together".

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Photosynthesis

The Light Reactions

The light reactions are the first set of chemical reactions in the carbon fixing cycle, which is central to all photosynthetic organisms. They occur in the thylakoid membranes of the chloroplasts in the chloroplast. The light reactions are the only reactions that can occur in the dark. The light reactions produce ATP and NADPH, which are used by the Calvin cycle.

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Photosynthesis

Electron Flow

In physics, electron flow, or the drift of electrons, is the movement of electrons through a conductor due to the force of an electric field. Electrons are bound to the nuclei of atoms by the attraction of opposite electric charges. When an electric field is applied across a conductor, electrons are forced to move by the field and it is this movement that constitutes an electric current. Electrons that are free to move (i.e. not bound to an atom) are called free electrons.

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Photosynthesis

The Calvin Cycle

In biology, photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can later be released to fuel the organisms' activities. In most cases, oxygen is also released as a waste product. Most plants, most algae, and cyanobacteria perform photosynthesis. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthesis in plants and algae is carried out by the organelles called chloroplasts. In the first stage, light-dependent reactions or light reactions capture the energy of light and use it to make the energy-storage molecules ATP and NADPH. In the second stage, the light-independent reactions use these products to capture and reduce carbon dioxide. In the third stage, the products are used to synthesize carbohydrates, lipids, and other products.

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Photosynthesis

Photorespiration

In botany, photorespiration is a process in which the enzyme ribulose 1,5-bisphosphate carboxylase oxygenase (RuBisCO) removes carbon dioxide from the 3-phosphoglycerate produced in photosynthesis, which causes loss of carbon in the form of the organic compound glycolate. Photorespiration is an oxygen-requiring process that happens in the stroma of chloroplasts in plants. It is a process that takes place in the chloroplasts of plants, and it is a process that is necessary for the plant to survive. The product of photorespiration is glycolate, which is then converted to glycine in the mitochondria. Glycolate is a toxic substance, and the plant is able to convert it into glycine, which is then excreted.

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Photosynthesis

Alternative Photosynthesis Pathways

In biology, photosynthesis is a process used by plants and other organisms to convert light energy, normally from the Sun, into chemical energy that can later be released to fuel the organisms' activities. In most cases, oxygen is also released as a waste product. Most plants, most algae, and cyanobacteria perform photosynthesis. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. It also occurs in some species of fungi. Photosynthesis is crucial for all aerobic life on Earth. In all photosynthetic organisms, some energy from sunlight is used to reduce carbon dioxide to sugar, either directly, or indirectly after making organic compounds. In all plants, algae, and cyanobacteria, this carbon fixation is performed by a sequence of enzyme-catalyzed reactions called the Calvin cycle, which reduces the CO to sugar, which is later converted to the simple carbohydrate starch or sucrose and to other products. In green plants, the products are cellulose and lignin, and in algae they are starch and glycerol.

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Photosynthesis

Mitochondria vs. Chloroplasts

In biology, photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can later be released to fuel the organisms' activities. In most cases, oxygen is also released as a waste product. Most plants, most algae, and cyanobacteria perform photosynthesis; such organisms are called photoautotrophs. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can create their own food (Greek: ???, photos, "light" and ????????, autotroph?, "self-nourishment"). The energy stored in organic molecules by photosynthesis is later used by the plant for growth and production of other organic compounds, including sugars, starches, and cellulose.

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Photosynthesis

Life on Earth Depends on Photosynthesis

In biology, photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that can later be released to fuel the organisms' activities. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. It does not occur in some species of bacteria, such as cyanobacteria. Both primary production and the secondary metabolic pathways of photosynthesis use light as an energy source, and are essential for maintaining life on earth.

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