Information about Metabolic Pathway
In biochemistry, a metabolic pathway is a series of chemical reactions occurring within a cell. In each pathway a principal chemical is modified by chemical reactions. These reactions are accelerated, more accurately catalyzed, by enzymes. Dietary minerals, vitamins and other cofactors are often needed by the enzyme to perform its task. Many pathways are elaborate. Various metabolic pathways within each cell form that cell's metabolic network. Pathways are needed by an organism to keep its homeostasis.
Metabolism is a step by step modification of the initial molecule to shape it into another product. The result can be used in one of three ways.
Several distinct but linked metabolic pathways are used by cells to transfer the energy released by breakdown of fuel molecules to ATP. These occur within all living organisms in some forms:
Other pathways occurring in (most or) all living organisms include:
Catabolism is the set of metabolic pathways that break down molecules into smaller units and release energy.
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Control theory is an interdisciplinary branch of engineering and mathematics, that deals with the behavior of dynamical systems. The desired output of a system is called the reference.
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Metabolism is a step by step modification of the initial molecule to shape it into another product. The result can be used in one of three ways.
- Stored by the cell.
- Be used immediately, as a metabolic product.
- Initiate another metabolic pathway, called a flux generating step.
Overview
Metabolic pathways often have these properties:- They contain many steps, like a cascade. The first step is usually irreversible. The other steps need not be irreversible and in many cases, the pathway can go in opposite direction depending on the current need of the cell.
- *Glycolysis features excellent examples of these features:
- #As glucose enters a cell it is immediately phosphorylated by ATP to glucose 6-phosphate in the irreversible first step. This is to prevent the glucose leaving the cell.
- #In times of excess lipid or protein energy sources glycolysis may run in reverse (gluconeogenesis) in order to produce glucose 6-phosphate for storage as glycogen or starch.
- They are regulated, usually by feedback inhibition, or by a cycle where one of the products in the cycle starts the reaction again, such as the Krebs Cycle (see below).
- Anabolic and catabolic pathways in eukaryotes are separated by either compartmentation or by the use of different enzymes and cofactors.
Major metabolic pathways
)
Cellulose and sucrose
metabolism
metabolism
Starch and glycogen
metabolism
metabolism
Other sugar
metabolism
metabolism
Aspartate amino acid
group synthesis
group synthesis
Porphyrins and
corrinoids
metabolism
corrinoids
metabolism
Glutamate amino
acid group
synthesis
acid group
synthesis
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Cellular respiration
Several distinct but linked metabolic pathways are used by cells to transfer the energy released by breakdown of fuel molecules to ATP. These occur within all living organisms in some forms:
Other pathways occurring in (most or) all living organisms include:
- Fatty acid oxidation (β-oxidation)
- Gluconeogenesis
- HMG-CoA reductase pathway (isoprene prenylation chains, see cholesterol)
- Pentose phosphate pathway (hexose monophosphate shunt)
- Porphyrin synthesis (or heme synthesis) pathway
- Urea cycle
- Photosynthesis (plants, algae, cyanobacteria)
- Chemosynthesis (some bacteria)
See also
External links
- BioCyc: Metabolic network models for hundreds of organisms
- KEGG: Kyoto Encyclopedia of Genes and Genomes
- MetaCyc: A database of nonredundant, experimentally elucidated metabolic pathways (900+ pathways from more than 800 different organisms).
- Metabolism, Cellular Respiration and Photosynthesis - The Virtual Library of Biochemistry and Cell Biology
- PathCase Pathways Database System
- Interactive Flow Chart of the Major Metabolic Pathways
Metabolism |
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| Catabolism - Anabolism Metabolic pathway - Metabolic network - Cellular respiration (Anaerobic/Aerobic) Protein metabolism - Carbohydrate metabolism - Lipid metabolism - Iron metabolism |
Biochemistry is the study of the chemical processes in living organisms.[1] The word "biochemistry" comes from the Greek word βιοχημεία biochēmeia, which means "the chemistry of life.
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Metabolism is the complete set of chemical reactions that occur in living cells. These processes are the basis of life, allowing cells to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories.
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chemical reaction is a process that results in the interconversion of chemical substances.[1] The substance or substances initially involved in a chemical reaction are called reactants.
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catalysis is the acceleration (increase in rate) of a chemical reaction by means of a substance called a catalyst, which is itself not consumed by the overall reaction.
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Enzymes are proteins that catalyze (i.e. accelerate) chemical reactions.[1] In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, the products.
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EC1 Oxidoreductases/list - EC2 Transferases/list - EC3 Hydrolases/list - EC4 Lyases/list - EC5 Isomerases/list - EC6 Ligases/list
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A metabolic network is the complete set of metabolic and physical processes that determine the physiological and biochemical properties of a cell. As such, these networks comprise the chemical reactions of metabolism as well as the regulatory interactions that guide these reactions.
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Plantae Chromalveolata Heterokontophyta Haptophyta Cryptophyta Alveolata
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Homeostasis is the property of either an open system or a closed system, especially a living organism, to regulate the state of its internal environment so as to maintain a stable, constant condition.
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In biochemistry, a substrate is a molecule upon which an enzyme acts. Enzymes catalyze chemical reactions involving the substrate(s). The substrate binds with the enzyme's active site, and an enzyme-substrate complex is formed.
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Anabolism is the set of metabolic pathways that construct molecules from smaller units. These reactions require energy. One way of categorizing metabolic processes, whether at the cellular, organ or organism level is as 'anabolic' or 'catabolic', which is the opposite.
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- For the related metabolic process, see anabolism.
Catabolism is the set of metabolic pathways that break down molecules into smaller units and release energy.
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Embden-Meyerhof pathway, initially explained by Gustav Embden and Otto Meyerhof. The term can be taken to include alternative pathways, such as the Entner-Doudoroff Pathway. However, glycolysis will be used here as a synonym for the Embden-Meyerhof pathway.
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Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. The living cell uses it as a source of energy and metabolic intermediate.
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Phosphorylation is the addition of a phosphate (PO4) group to a protein molecule or a small molecule. Another way to define it would be the introduction of a phosphate group into an organic molecule.
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Adenosine 5'-triphosphate (ATP) is a multifunctional nucleotide that is most important as a "molecular currency" of intracellular energy transfer. In this role, ATP transports chemical energy within cells for metabolism.
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Glucose 6-phosphate (also known as Robison ester) is glucose sugar phosphorylated on carbon 6. This compound is very common in cells as the vast majority of glucose entering a cell will become phosphorylated in this way.
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Lipids can be broadly defined as any fat-soluble (hydrophobic), naturally-occurring molecules. The term is more-specifically used to refer to fatty-acids and their derivatives (including tri-, di-, and monoglycerides and phospholipids) as well as other fat-soluble sterol-containing
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Proteins are large organic compounds made of amino acids arranged in a linear chain and joined together by peptide bonds between the carboxyl and amino groups of adjacent amino acid residues.
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Embden-Meyerhof pathway, initially explained by Gustav Embden and Otto Meyerhof. The term can be taken to include alternative pathways, such as the Entner-Doudoroff Pathway. However, glycolysis will be used here as a synonym for the Embden-Meyerhof pathway.
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Gluconeogenesis is the generation of glucose from non-sugar carbon substrates like pyruvate, lactate, glycerol, and glucogenic amino acids (primarily alanine and glutamine).
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Glucose 6-phosphate (also known as Robison ester) is glucose sugar phosphorylated on carbon 6. This compound is very common in cells as the vast majority of glucose entering a cell will become phosphorylated in this way.
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Glycogen is a polysaccharide of glucose (Glc) which functions as the primary short term energy storage in animal cells. It is made primarily by the liver and the muscles, but can also be made by the brain, uterus, and the vagina.
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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).
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For control theory in psychology and sociology, see .
Control theory is an interdisciplinary branch of engineering and mathematics, that deals with the behavior of dynamical systems. The desired output of a system is called the reference.
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Enzyme inhibitors are molecules that bind to enzymes and decrease their activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used as herbicides and pesticides.
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citric acid cycle, also known as the tricarboxylic acid (TCA) cycle, the Krebs cycle, or Szent-Györgyi-Krebs cycle (after Hans Adolf Krebs and Albert Szent-Györgyi who first determined the chemical intermediates and reaction sequence of the cycle), is a series
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Anabolism is the set of metabolic pathways that construct molecules from smaller units. These reactions require energy. One way of categorizing metabolic processes, whether at the cellular, organ or organism level is as 'anabolic' or 'catabolic', which is the opposite.
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