Other articles where Chemiosmotic theory is discussed: photosynthesis: The process of photosynthesis: the conversion of light energy to ATP: This chemiosmotic. chemiosmotic theory. 17 October The Royal Swedish Academy of Sciences decided to award the Nobel Prize in Chemistry to. Dr Peter Mitchell. Chemiosmotic theory. Chemiosmotic theory proposed by Peter Mitchell The transport of protons from matrix to intermembrane space is accompanied by the generation of a proton gradient across the membrane.


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Chemiosmotic theory - Biology-Online Dictionary | Biology-Online Dictionary

Mitchell studied the mitochondrion, the organelle that produces energy for the cell. ATP is made within the mitochondrion by adding a phosphate group to ADP in a process known as oxidative phosphorylation. Mitchell was able to determine how the different enzymes involved in the conversion of ADP to ATP are distributed within the membranes that partition the interior of the mitochondrion.

As electrons are passed down the chain, protons are pumped across the membrane between the inner membrane and outer chemiosmotic theory of the cristae or thylakoids.

This results in a pH and electrical gradient.

Chemiosmotic theory | biochemistry |

The protons move back into the matrix through a pore created by ATP synthetase allowing the enzyme to make ATP at the expense of this gradient. The Nobel Prize for Chemistry inawarded to Peter Mitchell as the sole recipient, recognized his predominant contribution towards establishing the validity of the chemiosmotic hypothesis, and ipso facto, the long struggle to convince an initially hostile establishment.

Life processes, as all events that involve work, require energy, and it is quite natural that such activities as muscle contraction, nerve conduction, active transport, growth, chemiosmotic theory, as well as the synthesis of all the substances that are necessary for carrying out and regulating these activities, could not take place without an adequate supply of energy.


It is now well established that the cell is the smallest biological entity capable of handling energy. Common to all living cells is the ability, by means of suitable enzymes, to derive energy chemiosmotic theory their environment, to convert it into a biologically useful form, and to utilize it for driving various energy requiring processes.

Cells of green plants as well as certain bacteria and algae can capture energy by means of chlorophyll directly from sunlight — the ultimate source of energy for all life on Earth — and utilize it, through photosynthesis, to convert carbon dioxide and water into organic compounds.

Other cells, chemiosmotic theory those of all animals and many bacteria, are entirely dependent for their existence on organic compounds which they take up as nutrients from their environment.

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Through a process called cell respiration, these compounds are oxidized by atmospheric oxygen to carbon dioxide and water. During both photosynthesis and respiration, energy is conserved in a compound chemiosmotic theory adenosine triphosphate, abbreviated as ATP.

When ATP is chemiosmotic theory into adenosine diphosphate ADP and inorganic phosphate Pia relatively large amount of energy is liberated, which can be utilized, in the presence of specific enzymes, to drive various energy-requiring processes.

The two processes have several features in common, both in their enzyme composition — both involve an interaction between oxidizing electron-transferring and phosphorylating enzymes — and in their association with cellular membranes.

In higher cells, photophosphorylation and oxidative phosphorylation occur in specific membrane-enclosed organelles, chloroplasts and mitochondria, respectively; in bacteria, both these processes are associated with the cell membrane.

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The above concepts had been broadly outlined by about the beginning of the s, but the exact mechanisms by which electron transfer is coupled to ATP synthesis in oxidative phosphorylation and chemiosmotic theory photophosphorylation remained unknown.

Many hypotheses were formulated, especially with regard to the mechanism of oxidative phosphorylation; most of these postulated a direct chemical interaction between chemiosmotic theory and phosphorylating enzymes.

Despite intensive research in many laboratories, however, no experimental evidence could be obtained for any of these hypotheses. At this stage, inMitchell proposed an alternative mechanism for the coupling of electron transfer to ATP synthesis, based on an indirect interaction between oxidizing and phosphorylating enzymes.

Chemiosmotic theory -

He suggested that the flow of electrons through the enzymes of the respiratory or photosynthetic electron-transfer chains drives positively charged hydrogen ions, or protons, across the membranes of mitochondria, chloroplasts and bacterial cells.

As chemiosmotic theory result, an electrochemical proton gradient is created across the membrane. The energy available in the electrons is used to pump protons from the matrix across the stroma, storing energy in chemiosmotic theory form of a transmembrane electrochemical gradient. The protons move back across the inner membrane through the enzyme ATP synthase.

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