Metabolism Portal

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 & 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. Image File history File links Portal. ... Biochemistry is the study of the chemical processes and transformations in living organisms. ... A few of the metabolic pathways in a cell. ... Chemistry - the study of atoms, made of nuclei (conglomeration of center particles) and electrons (outer particles), and the structures they form. ... 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. Cells in culture, stained for keratin (red) and DNA (green). ... Vapours of hydrogen chloride in a beaker and ammonia in a test tube meet to form a cloud of a new substance, ammonium chloride A chemical reaction is a process that results in the interconversion of chemical substances. ... In chemistry and biology, catalysis is the acceleration (increase in rate) of a chemical reaction by means of a substance, called a catalyst, that is itself not consumed by the overall reaction. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... Cofactor may refer to any of the following: Minor (linear algebra) as an alternative name for the determinant of a smaller matrix than that which it describes Cofactor (biochemistry) is a substance that needs to be present in addition to an enzyme for a certain reaction to take place. ... With the sequencing of complete genomes, it is now possible to reconstruct the network of biochemical reactions in many organisms, from bacteria to human. ... This article does not cite any references or sources. ... Homeostasis is the property of either an open system or a closed system,[1] especially a living organism, to regulate its internal environment to maintain a stable, constant condition. ...

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.

A molecule called a substrate enters a metabolic pathway depending on the needs of the cell & the availability of the substrate. An increase in concentration of anabolical and catabolical end products would slow the metabolic rate for that particular pathway. In biochemistry, a substrate is a molecule upon which an enzyme acts. ... Anabolism is the metabolic process that builds larger molecules from smaller ones. ... Anabolism is the aspect of metabolism that contributes to growth. ...

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:

1. 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.
2. 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.

Glycolysis is a metabolic pathway by which a 6-carbon glucose (Glc) molecule is oxidized to two molecules of pyruvic acid (Pyr). ... Glucose (Glc), a monosaccharide (or simple sugar), is the most important carbohydrate in biology. ... Phosphorylation is the addition of a phosphate (PO4) group to a protein or a small molecule or the introduction of a phosphate group into an organic molecule. ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ... Glucose-6-phosphate (G6P) is a phosphorylated glucose molecule on carbon 6. ... A polyunsaturated triglyceride. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Glycolysis is a metabolic pathway by which a 6-carbon glucose (Glc) molecule is oxidized to two molecules of pyruvic acid (Pyr). ... Pyruvic acid Oxaloacetic acid Phosphoenolpyruvate Fructose 1,6-bisphosphate Fructose 6-phosphate Glucose-6-phosphate Glucose Gluconeogenesis is the generation of glucose from non-sugar carbon substrates like pyruvate, lactate, glycerol, and amino acids (primarily alanine and glutamine). ... Glucose-6-phosphate (G6P) is a phosphorylated glucose molecule on carbon 6. ... Electron micrograph of a section of a liver cell showing glycogen deposits as accumulations of electron dense particles (arrows). ... Starch (CAS# 9005-25-8) is a complex carbohydrate which is insoluble in water; it is used by plants as a way to store excess glucose. ... In cybernetics and control theory, feedback is a process whereby some proportion or in general, function, of the output signal of a system is passed (fed back) to the input. ... The citric acid cycle (also known as the tricarboxylic acid cycle, the TCA cycle, or the Krebs cycle) is a series of chemical reactions of central importance in all living cells that utilize oxygen as part of cellular respiration. ... Anabolism is the metabolic process that builds larger molecules from smaller ones. ... Anabolism is the aspect of metabolism that contributes to growth. ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista Alternative phylogeny Unikonta Opisthokonta 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. ... Schematic of typical animal cell, showing subcellular components. ...

Major metabolic pathways

Image File history File links Metabolism_790px_partly_labeled. ...

Glucuronate metabolism

Pentose interconversion

Inositol metabolism

Cellulose and sucrose
metabolism

Starch and glycogen
metabolism

Other sugar
metabolism

Pentose phosphate pathway

Glycolysis and Gluconeogenesis

Amino sugars metabolism

Small amino acid synthesis

Branched amino acid
synthesis

Purine biosynthesis

Histidine metabolism

Aromatic amino
acid synthesis

Pyruvate
decarboxylation

Anaerobic
respiration

Fatty acid
metabolism

Urea cycle

Aspartate amino acid
group synthesis

Porphyrins and
corrinoids
metabolism

Citric acid cycle

Glutamate amino
acid group
synthesis

Pyrimidine biosynthesis

 v • d • e 

	All pathway labels on this image are links, simply click to access the article.
	A high resolution labeled version of this image is available here.

Ball-and-stick model of β-D-glucuronic acid The α-D form of glucuronic acid. ... A pentose is a monosaccharide with five carbon atoms. ... Inositol, (of which the most prominent naturally-ocurring form is myo-inositol, cis-1,2,3,5-trans-4,6-cyclohexanehexol), is a carbocyclic polyol that plays an important role as the structural basis for a number of secondary messengers in eukaryotic cells, including inositol phosphates, phosphatidylinositol (PI) and phosphatidylinositol... The pentose phosphate pathways Nonoxidative phase The pentose phosphate pathway (also called Phosphogluconate Pathway, or Hexose Monophosphate Shunt [HMP shunt]) is a process that serves to generate NADPH and the synthesis of pentose (5-carbon) sugars. ... Glycolysis is a metabolic pathway by which a 6-carbon glucose (Glc) molecule is oxidized to two molecules of pyruvic acid (Pyr). ... Pyruvic acid Oxaloacetic acid Phosphoenolpyruvate Fructose 1,6-bisphosphate Fructose 6-phosphate Glucose-6-phosphate Glucose Gluconeogenesis is the generation of glucose from non-sugar carbon substrates like pyruvate, lactate, glycerol, and amino acids (primarily alanine and glutamine). ... Glucosamine Sialic acid In chemistry, an amino sugar contains an amine group in place of a hydroxyl group. ... Alanine transaminase or ALT is a transaminase enzyme (EC 2. ... leucine isoleucine valine The phrase branched-chain amino acids or BCAA is sometimes used to refer to the amino acids having aliphatic side-chains that are non-linear. ... This article or section does not cite its references or sources. ... The histidine bound haem group of succinate dehydrogenase, an electron carrier in the mitochondrial electron transfer chain. ... phenylalanine tryptophan tyrosine thyroxine Aromatic amino acids are amino acids which include an aromatic ring. ... The Pyruvate decarboxylation reaction links the metabolic pathways glycolysis and the citric acid cycle. ... Anaerobic respiration refers to the oxidation of molecules in the absence of oxygen to produce energy, in opposition to Aerobic respiration which does use oxygen. ... This article or section is in need of attention from an expert on the subject. ... The reactions of the urea cycle. ... Overview of the citric acid cycle The citric acid cycle (also known as the tricarboxylic acid cycle, the TCA cycle, or the Krebs cycle, after Hans Adolf Krebs who identified the cycle) is a series of chemical reactions of central importance in all living cells that use oxygen as part... Pyrimidine biosynthesis occurs both in the body and through organic synthesis. ... Image File history File links Gtk-dialog-info. ... Image File history File links Metabolism_790px. ...

Cellular respiration

Main article: 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: Cellular respiration describes the metabolic reactions and processes that take place in a cell to obtain biochemical energy from fuel molecules. ... A fuel molecule is a molecule metabolized by a cell to generate ATP. Types Carbohydrate Fat Protein ... Adenosine 5-triphosphate (ATP) is a multifunctional nucleotide that is most important as a molecular currency of intracellular energy transfer. ...

1. Glycolysis
2. Anaerobic respiration
3. Krebs cycle / Citric acid cycle
4. Oxidative phosphorylation

Other pathways occurring in (most or) all living organisms include: Glycolysis is a metabolic pathway by which a 6-carbon glucose (Glc) molecule is oxidized to two molecules of pyruvic acid (Pyr). ... Anaerobic respiration refers to the oxidation of molecules in the absence of oxygen to produce energy, in opposition to Aerobic respiration which does use oxygen. ... The citric acid cycle (also known as the tricarboxylic acid cycle, the TCA cycle, or the Krebs cycle) is a series of chemical reactions of central importance in all living cells that utilize oxygen as part of cellular respiration. ... Overview of the citric acid cycle The citric acid cycle (also known as the tricarboxylic acid cycle, the TCA cycle, or the Krebs cycle, after Hans Adolf Krebs who identified the cycle) is a series of chemical reactions of central importance in all living cells that use oxygen as part... The Electron Transport Chain. ...

• 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

Creation of energetic compounds from non-living matter: Fatty acids are an important source of energy for many organisms. ... Pyruvic acid Oxaloacetic acid Phosphoenolpyruvate Fructose 1,6-bisphosphate Fructose 6-phosphate Glucose-6-phosphate Glucose Gluconeogenesis is the generation of glucose from non-sugar carbon substrates like pyruvate, lactate, glycerol, and amino acids (primarily alanine and glutamine). ... The HMG-CoA reductase pathway, also known as MVA pathway or mevalonate-dependent (MAD) route, is an important cellular metabolic pathway present in virtually all organisms. ... Isoprene is a common synonym for the chemical compound 2-methyl-1,3-butadiene. ... Cholesterol is a sterol (a combination steroid and alcohol) and a lipid found in the cell membranes of all body tissues, and transported in the blood plasma of all animals. ... The pentose phosphate pathways Nonoxidative phase The pentose phosphate pathway (also called Phosphogluconate Pathway, or Hexose Monophosphate Shunt [HMP shunt]) is a process that serves to generate NADPH and the synthesis of pentose (5-carbon) sugars. ... Structure of porphine, the simplest porphyrin. ... Structure of Heme b A heme or haem is a prosthetic group that consists of an iron atom contained in the center of a large heterocyclic organic ring called a porphyrin. ... The reactions of the urea cycle. ...

• Photosynthesis (plants, algae, cyanobacteria)
• Chemosynthesis (some bacteria)

The leaf is the primary site of photosynthesis in plants. ... Orders The taxonomy of the Cyanobacteria is currently under revision. ... Chemosynthesis is the biological conversion of 1-carbon molecules (usually carbon dioxide or methane) and nutrients into organic matter using the oxidation of inorganic molecules (e. ...

See also

• Metabolism
• Metabolic network
• Metabolic network modelling

A few of the metabolic pathways in a cell. ... With the sequencing of complete genomes, it is now possible to reconstruct the network of biochemical reactions in many organisms, from bacteria to human. ... There are very few or no other articles that link to this one. ...

External links

• Metabolism, Cellular Respiration and Photosynthesis - The Virtual Library of Biochemistry and Cell Biology
• KEGG: Kyoto Encyclopedia of Genes and Genomes
• MetaCyc: a database of nonredundant, experimentally elucidated metabolic pathways (700 pathways from more than 600 different organisms).
• PathCase Pathways Database System
• Interactive Flow Chart of the Major Metabolic Pathways
• Biocyc Very detailed searchable pathways system