anabolic pathways

Examples of anabolic pathways in the following topics:

• Repression of Anabolic Pathways

  • Repression of anabolic pathways is regulated by altering transcription rates.

• Steroids

  • Steroid biosynthesis is an anabolic metabolic pathway that produces steroids from simple precursors.
  • A unique biosynthetic pathway is followed in animals compared to many other organisms, making the pathway a common target for antibiotics and other anti-infective drugs.
  • The non-mevalonate pathway or 2-C-methyl-D-erythritol 4-phosphate/1-deoxy-D-xylulose 5-phosphate pathway (MEP/DOXP pathway) of isoprenoid biosynthesis is an alternative metabolic pathway leading to the formation of isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP).
  • The classical mevalonate pathway or HMG-CoA reductase pathway is an important cellular metabolic pathway present in all higher eukaryotes and many bacteria.
  • In contrast to the classical mevalonate pathway of isoprenoid biosynthesis, plants and apicomplexan protozoa such as malaria parasites have the ability to produce their isoprenoids (terpenoids) using an alternative pathway, the non-mevalonate pathway, which takes place in their plastids.

• Biosynthesis and Energy

  • Biosynthesis is often referred to as the anabolism branch of metabolism that results in complex proteins such as vitamins.
  • A majority of the organic compounds required by microorganisms are produced via biosynthetic pathways.
  • Biosynthetic metabolism (also known as anabolism) involves the synthesis of macromolecules from specific building blocks.
  • The major pathways utilized to ensure fixation of carbon dioxide include: the Calvin cycle, the reductive TCA cycle, and the acetyl-CoA pathway.
  • In the acetyl-CoA pathway, carbon dioxide is reduced to carbon monoxide and then acetyl-CoA.

• The Pentose Phosphate Shunt

  • There are two distinct phases in the pathway: the oxidative phase and the non-oxidative phase .
  • The second phase of this pathway is the non-oxidative synthesis of 5-carbon sugars.
  • Glucose-6-phosphate dehydrogenase is the rate-controlling enzyme in this pathway.
  • While the PPP does involve oxidation of glucose, its primary role is anabolic rather than catabolic, using the energy stored in NADPH to synthesize large, complex molecules from small precursors.
  • The pentose phosphate pathway generates reducing equivalents in the form of NADPH.

• Intermediates Produced During the Calvin Cycle

  • The Calvin Cycle is characterized as a carbon fixation pathway.
  • The additional 3-PGA is utilized in additional metabolic pathways such as glycolysis and gluconeogenesis.
  • The ADP product that is produced via the breakdown of ATP will be utilized in additional pathways and be converted back into ATP.
  • The functions that require NADP+ include anabolic reactions such as lipid and nucleic acid synthesis.
  • The G3P, which is destined to exit the cycle, will be used for carbohydrate synthesis and additional pathways.

• Types of Catabolism

  • The purpose of catabolic reactions is to provide the energy and components needed by anabolic reactions.
  • Pyruvate is an intermediate in several metabolic pathways, but the majority is converted to acetyl-CoA and fed into the citric acid cycle.
  • An alternative route for glucose breakdown is the pentose phosphate pathway, which reduces the coenzyme NADPH and produces pentose sugars such as ribose, the sugar component of nucleic acids.
  • The oxidation pathway starts with the removal of the amino group by a transaminase.

• The Entner–Doudoroff Pathway

  • The Entner–Doudoroff pathway is an alternate series of reactions that catabolize glucose to pyruvate.
  • The Entner–Doudoroff pathway describes an alternate series of reactions that catabolize glucose to pyruvate using a set of enzymes different from those used in either glycolysis or the pentose phosphate pathway .
  • Most bacteria use glycolysis and the pentose phosphate pathway.
  • This pathway was first reported in 1952 by Michael Doudoroff and Nathan Entner.
  • There are a few bacteria that substitute classic glycolysis with the Entner-Doudoroff pathway.

• Substrates for Biosynthesis

  • These pathways are necessary for survival and cellular function.
  • These processes require pathways that are often multi-step.
  • An additional central metabolic pathway includes glycolysis.
  • Additional pathways that require substrates or metabolites produced by the glycolytic pathway include: gluconeogenesis, lipid metabolism, the pentose phosphate pathway, and the TCA.
  • An overview of the glycolytic pathway.

• The Acetyl-CoA Pathway

  • The acetyl coenzyme A (CoA) pathway, commonly referred to as the Wood-Ljungdahl pathway or the reductive acetyl-CoA pathway, is one of the major metabolic pathways utilized by bacteria.
  • The following is a brief overview of the acetyl-CoA pathway. .
  • The acetyl-CoA pathway begins with the reduction of a carbon dioxide to carbon monoxide.
  • Acetyl-CoA synthetase is a class of enzymes that is key to the acetyl-CoA pathway.
  • Methanogens are able to utilize the acetyl-CoA pathway to fix carbon dioxide.

• The 3-Hydroxypropionate Cycle

  • The 3-hydroxypropionate cycle is a carbon fixation pathway that results in the production of acetyl-CoA and glyoxylate.
  • Carbon fixation is a key pathway in numerous microorganisms, resulting in the formation of organic compounds deemed necessary for cellular processes.
  • One of the pathways that is utilized for carbon fixation is the 3-hydroxypropionate cycle.
  • The ability of Chloroflexus aurantiacus to utilize this pathway is unique.
  • An image of Chloroflexus aurantiacus, a green nonsulfur bacteria that utilizes the 3-hydroxypropionate pathway.