oxidative phosphorylation

(noun)

A metabolic pathway that uses energy released by the oxidation of nutrients to produce adenosine triphosphate (ATP).

Related Terms

  • ATP synthase
  • chemiosmosis

Examples of oxidative phosphorylation in the following topics:

  • Chemiosmosis and Oxidative Phosphorylation

    • The production of ATP using the process of chemiosmosis in mitochondria is called oxidative phosphorylation.
    • In oxidative phosphorylation, the hydrogen ion gradient formed by the electron transport chain is used by ATP synthase to form ATP.
  • Electron Transport Chain

    • The electron transport chain uses the electrons from electron carriers to create a chemical gradient that can be used to power oxidative phosphorylation.
    • Oxidative phosphorylation is a highly efficient method of producing large amounts of ATP, the basic unit of energy for metabolic processes.
    • As a result, the iron ion at its core is reduced and oxidized as it passes the electrons, fluctuating between different oxidation states: Fe2+ (reduced) and Fe3+ (oxidized).
  • Importance of Glycolysis

    • Glycolysis is the first pathway of cellular respiration that oxidizes glucose molecules.
    • It is followed by the Krebs cycle and oxidative phosphorylation to produce ATP.
  • Essential Nutrients for Plants

    • As part of ATP, phosphorus enables food energy to be converted into chemical energy through oxidative phosphorylation.
  • The Energy-Releasing Steps of Glycolysis

    • The sugar is then phosphorylated by the addition of a second phosphate group, producing 1,3-bisphosphoglycerate.
    • The continuation of the reaction depends upon the availability of the oxidized form of the electron carrier NAD+.
    • Thus, NADH must be continuously oxidized back into NAD+ in order to keep this step going.
    • (This is an example of substrate-level phosphorylation. ) A carbonyl group on the 1,3-bisphosphoglycerate is oxidized to a carboxyl group, and 3-phosphoglycerate is formed.
    • The second half of glycolysis involves phosphorylation without ATP investment (step 6) and produces two NADH and four ATP molecules per glucose.
  • Connecting Lipids to Glucose Metabolism

    • Glycerol can be phosphorylated to glycerol-3-phosphate, which continues through glycolysis.
    • Fatty acids are catabolized in a process called beta-oxidation that takes place in the matrix of the mitochondria and converts their fatty acid chains into two carbon units of acetyl groups, while producing NADH and FADH2.
  • Citric Acid Cycle

    • If this transfer does not occur, the oxidation steps of the citric acid cycle also do not occur.
    • This energy is used in substrate-level phosphorylation (during the conversion of the succinyl group to succinate) to form either guanine triphosphate (GTP) or ATP.
    • The last step in the citric acid cycle regenerates oxaloacetate by oxidizing malate.
    • Through a series of steps, citrate is oxidized, releasing two carbon dioxide molecules for each acetyl group fed into the cycle.
    • In the process, three NAD+ molecules are reduced to NADH, one FAD molecule is reduced to FADH2, and one ATP or GTP (depending on the cell type) is produced (by substrate-level phosphorylation).
  • Termination of the Signal Cascade

    • Signal cascades convey signals to the cell through the phosphorylation of molecules by kinases.
    • A major component of cell signaling cascades is the phosphorylation of molecules by enzymes known as kinases.
    • Phosphorylation adds a phosphate group to serine, threonine, and tyrosine residues in a protein, changing their shapes, and activating or inactivating the protein .
    • In protein phosphorylation, a phosphate group is added to residues of the amino acids serine, threonine, and tyrosine.
  • Methods of Intracellular Signaling

    • Various kinases are named for the substrate they phosphorylate.
    • Phosphorylation of serine and threonine residues often activates enzymes.
    • Phosphorylation may activate or inactivate enzymes; the reversal of phosphorylation, dephosphorylation by a phosphatase, will reverse the effect.
    • It phosphorylates serine and threonine residues of its target proteins, activating them in the process.
    • Enzymes known as kinases phosphorylate PI to form PI-phosphate (PIP) and PI-bisphosphate (PIP2).
  • Processes of the Light-Dependent Reactions

    • This reaction center, known as P700, is oxidized and sends a high-energy electron to reduce NADP+ to NADPH.
    • Cyclic phosphorylation is important to maintain the right proportions of NADPH and ATP, which will carry out light-independent reactions later on.
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