The Microbiology Metabolism and Enzymatic Processes
BIO 320 - MICROBIOLOGY Chapter 8 Part 1 - Metabolism Enzymes, Matter, and Energy ● Catabolism is the breakdown of complex compounds, whereas anabolism is the synthesis of complex molecules (anabolism). ● Organisms can be categorized based on where they get their carbon from. Heterotrophs employ fixed organic carbon components, whereas autotrophs use inorganic carbon dioxide to produce organic carbon. ● Moreover, classification of organisms based on their energy source is possible. Light is the source of energy for phototrophs. Chemical substances provide the energy for chemotrophs. Lithotrophs employ inorganic chemicals, whereas organotrophs use organic compounds. ● Electron donors in future redox processes are provided by the cellular electron carriers, which take in high-energy electrons from meals. The electron carriers FAD/FADH2, NAD+/NADH, and NADP+/NADPH are significant ones. ● The energy unit of the cell is adenosine triphosphate (ATP), which safely stores chemical energy in its two highly energetic phosphate bonds to be used later to power energy-intensive operations. ● Enzymes are biological catalysts that quicken chemical processes inside of cells by reducing the amount of energy needed to initiate the reaction. ● Exergonic processes in nature don't need any additional energy beyond activation energy to occur, and they even produce energy. They can still move along without enzymes, although slowly. On the other hand, endergonic processes need more energy than only activation energy to take place. In cells, endergonic and exergonic processes are connected, creating a favorable energy combination. ● The active site of the enzyme is where substances bind. Induced fit is the term used to describe how this process often modifies the structures of both the active site and the substrate, encouraging the creation of transition states. ● Cofactors are inorganic ions that maintain the conformation and operation of enzymes. Organic compounds known as coenzymes, which are frequently formed from vitamins, are necessary for efficient enzyme action. An apoenzyme is an enzyme that lacks a cofactor or coenzyme, whereas a holoenzyme is an enzyme that has a bound cofactor or coenzyme. ● Competitive inhibitors control the activity of enzymes by attaching to the active site and blocking substrate binding. Noncompetitive (allosteric) inhibitors attach to allosteric regions, causing an enzyme to shift shape and become inactive. When an enzyme early in a metabolic process is noncompetitively bound by a product of the route, feedback inhibition occurs, ultimately blocking the production of the product Carbohydrate catabolism ● The process of breaking down glucose begins with glycolysis, which results in the production of ATP, which is made possible by substrate-level phosphorylation, NADH, and two pyruvate molecules. Oxygen is neither required for, nor is glycolysis dependent upon, oxygen. ● A three-carbon pyruvate is decarboxylated after glycolysis to produce a two- carbon acetyl group along with the creation of NADH. The acetyl group is joined to coenzyme A, a significant carrier substance. ● Coenzyme A moves the two-carbon acetyl to the Krebs cycle after the transition phase, where the two carbons enter the cycle. One glycolysis-derived acetyl group per cycle turn is further oxidized, resulting in the production of three NADH molecules, one FADH2 molecule, one ATP molecule, and two CO2 molecules. ● There are further uses for the Krebs cycle. Amino acids, chlorophyll, fatty acids, and nucleotides are just a few of the crucial biological components that are synthesized using several of the intermediates. Cellular Respiration ● The majority of ATP produced during the metabolism of glucose in cells is produced by oxidative phosphorylation. ● A collection of membrane-associated protein complexes and related mobile accessory electron carriers make up an electron transport system (ETS). Prokaryotes' cytoplasmic membrane and eukaryotes' inner mitochondrial membrane both include the ETS. ● Electrons travel from electron carriers with more negative redox potential to those with more positive redox potential as each ETS complex has a distinct redox potential. ● Being the ultimate electron acceptor in aerobic respiration, oxygen is necessary for cells to function. To counteract the negative effects of oxygen radicals generated during aerobic respiration, a cell also requires a fully functioning Krebs cycle, a suitable cytochrome oxidase, and oxygen detoxifying enzymes. ● The ultimate transportation of electrons to the non-oxygen electron acceptors is carried out by anaerobic organisms via alternate electron transport system carriers. ● Microbes differ greatly in their electron transport system makeup, which can be utilized as a diagnostic tool to assist pinpoint certain diseases. ● The electron loses energy as it travels through an ETS from NADH and FADH2. The pumping of H+ across the membrane, which creates a proton motive force, stores this energy. ● By permitting hydrogen ions to return through the membrane via chemiosmosis with the help of ATP synthase, the energy of this proton motive force may be captured. Components of ATP synthase spin when hydrogen ions pass through along their electrochemical gradient, producing ATP from ADP and Pi by oxidative phosphorylation. ● During oxidative phosphorylation, aerobic respiration produces more ATP (up to 34 ATP molecules) than anaerobic respiration (between one and 32 ATP molecules) Read the full article













