Metabolism and energyThe analogy is made that a cell is a chemical factory. Explain why this might be an appropriate analogy. Bioluminesence and all other metabolic activities carried out by the tbe are precisely coordinated and controlled. The totality of an organisms chemical reactions. Describe what is meant by a metabolic pathway. Contrast catabolic pathways with anabolic pathways. Give examples of each type.
Chemistry for Biologists: Metabolism and energy
In biochemistry , a metabolic pathway is a linked series of chemical reactions occurring within a cell. The reactants, products, and intermediates of an enzymatic reaction are known as metabolites , which are modified by a sequence of chemical reactions catalyzed by enzymes.
However, set products are considered waste and removed from the cell. Different metabolic pathways function based on the position within a eukaryotic cell and the significance of the pathway in the given compartment of the cell. There are two types of metabolic pathways that are characterized by their ability to either synthesize molecules with the utilization of energy anabolic pathway or break down of complex molecules by releasing energy in the process catabolic pathway.
The degradative process of a catabolic pathway provides the energy required to conduct a biosynthesis of an anabolic pathway. Pathways are required for the maintenance of homeostasis within an organism and the flux of metabolites through a pathway is regulated depending on the needs of the cell and the availability of the substrate.
The end product of a pathway may be used immediately, initiate another metabolic pathway or be stored for later use. The metabolism of a cell consists of an elaborate network of interconnected pathways that enable the synthesis and breakdown of molecules anabolism and catabolism.
Each metabolic pathway consists of a series of biochemical reactions that are connected by their intermediates: Metabolic pathways are often considered to flow in one direction. Although all chemical reactions are technically reversible, conditions in the cell are often such that it is thermodynamically more favorable for flux to flow in one direction of a reaction.
For example, one pathway may be responsible for the synthesis of a particular amino acid, but the breakdown of that amino acid may occur via a separate and distinct pathway. One example of an exception to this "rule" is the metabolism of glucose.
Glycolysis results in the breakdown of glucose, but several reactions in the glycolysis pathway are reversible and participate in the re-synthesis of glucose gluconeogenesis. A catabolic pathway is a series of reactions that bring about a net release of energy in the form of a high energy phosphate bond formed with the energy carriers adenosine diphosphate ADP and guanosine diphosphate GDP to produce adenosine triphosphate ATP and guanosine triphosphate GTP , respectively.
The end products are often carbon dioxide, water, and ammonia. Coupled with an endergonic reaction of anabolism, the cell can synthesize new macromolecules using the original precursors of the anabolic pathway. The resulting chemical reaction within the metabolic pathway is highly thermodynamically favorable and, as a result, irreversible in the cell.
A core set of energy-producing catabolic pathways occur within all living organisms in some form. These pathways transfer the energy released by breakdown of nutrients into ATP and other small molecules used for energy e. All cells can perform anaerobic respiration by glycolysis. Additionally, most organisms can perform more efficient aerobic respiration through the citric acid cycle and oxidative phosphorylation. Additionally plants , algae and cyanobacteria are able to use sunlight to anabolically synthesize compounds from non-living matter by photosynthesis.
In contrast to catabolic pathways, anabolic pathways require an energy input to construct macromolecules such as polypeptides, nucleic acids, proteins, polysaccharides, and lipids.
Thus, an input of chemical energy through a coupling with an exergonic reaction is necessary. An anabolic pathway is a biosynthetic pathway, meaning that it combines smaller molecules to form larger and more complex ones.
Although gluconeogenesis is similar to the reverse pathway of glycolysis, it contains three distinct enzymes from glycolysis that allow the pathway to occur spontaneously. An amphibolic pathway is one that can be either catabolic or anabolic based on the availability of or the need for energy. The energy is utilized to conduct biosynthesis, facilitate movement, and regulate active transport inside of the cell.
These sets of chemical reactions contain both energy producing and utilizing pathways. The glyoxylate shunt pathway is an alternative to the tricarboxylic acid TCA cycle , for it redirects the pathway of TCA to prevent full oxidation of carbon compounds, and to preserve high energy carbon sources as future energy sources.
This pathway occurs only in plants and bacteria and transpires in the absence of glucose molecules. The flux of the entire pathway is regulated by the rate-determining steps. The rate-limiting step occurs near the beginning of the pathway and is regulated by feedback inhibition, which ultimately controls the overall rate of the pathway.
A covalent modification involves an addition or removal of a chemical bond, whereas a non-covalent modification also known as allosteric regulation is the binding of the regulator to the enzyme via hydrogen bonds , electrostatic interactions, and Van Der Waals forces. The rate of turnover in a metabolic pathway, also known as the metabolic flux , is regulated based on the stoichiometric reaction model, the utilization rate of metabolites, and the translocation pace of molecules across the lipid bilayer.
The aforementioned techniques synthesize a statistical interpretation of mass distribution in proteinogenic amino acids to the catalytic activities of enzymes in a cell.
From Wikipedia, the free encyclopedia. Cobalamins Vitamin B Nelson; Cox, Michael M. Lehninger principles of biochemistry 5th ed. Biochemistry and molecular biology. An Introduction to Metabolic Pathways by S. Life at the Molecular Level 4th ed. Web content by Neil D. New York, NY [u. Biology of plants 8. The science and applications of synthetic and systems biology workshop summary. Regulation of primary metabolic pathways in plants: The physiology and biochemistry of prokaryotes.
Metabolomics methods and protocols. Cellulose and sucrose metabolism. Starch and glycogen metabolism. Small amino acid synthesis. Branched amino acid synthesis. Aromatic amino acid synthesis. Aspartate amino acid group synthesis. Porphyrins and corrinoids metabolism. Glutamate amino acid group synthesis.
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. Metabolism , catabolism , anabolism. Metabolic pathway Metabolic network Primary nutritional groups.
Pentose phosphate pathway Fructolysis Galactolysis. Photosynthesis Anoxygenic photosynthesis Chemosynthesis Carbon fixation. Fatty acid degradation Beta oxidation Fatty acid synthesis. Steroid metabolism Sphingolipid metabolism Eicosanoid metabolism Ketosis Reverse cholesterol transport. Amino acid synthesis Urea cycle. Purine metabolism Nucleotide salvage Pyrimidine metabolism.
Electron acceptors are other than oxygen. Protein metabolism Protein synthesis Catabolism. Fatty acid metabolism Fatty acid degradation Beta oxidation Fatty acid synthesis.