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Introduction T o Metabolism

Introduction T o Metabolism. Objectives. Understand the concept of metabolism and metabolic pathway Identify types & characters of metabolic pathways- anabolic and catabolic Identify ATP as the energy currency of cells.

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Introduction T o Metabolism

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  1. Introduction To Metabolism

  2. Objectives • Understand the concept of metabolism and metabolic pathway • Identify types & characters of metabolic pathways- anabolic and catabolic • Identify ATP as the energy currency of cells

  3. Metabolismis the set of chemical rections that occur in a cell, which enable it to keep living, growing and dividing. • Simply, Metabolismis the sum of all biochemical pathways that occur inside cells.

  4. Metabolic pathways fall into three categories Anabolic pathways Catabolic pathways Amphibolicpathways

  5. Anabolic pathways = (Biosynthetic Pathways) • are those involved in the synthesis of compounds (more complex material) • E.g. synthesis of Protein & fuel reserves of triacylglycerol& glycogen. • Anabolic Pathways diverge, (Synthesizing Variable Biomolecules from a Limited Set of Building Blocks) • Anabolic pathways are endergonic(energy consuming or requiring )

  6. Catabolic pathways = (Degradative Pathways) • are involved in the breakdown of larger molecules, commonly involving oxidative reactions; • They are converging (covertingVariable Biomolecules into Limited number of products) • Produce: • reducing equivalents (e.g. NADH+H+)and, • mainly ATP via the respiratory chain • they are exergonic, = (Energy producing = or energy-yielding,)

  7. Amphibolicpathways (amphi · from the Greek for “on both sides”)  (Dual) • Occur at “crossroads” of metabolism, • acting as links between the anabolic and catabolic pathways, • e.g, the citric acid cycle (= Krebs cycle).

  8. Catabolic pathways converge to a few end products • Anabolic pathways diverge to synthesize many biomolecules • Some pathways serve both in catabolism and anabolism  Such pathways are amphibolic

  9. Different pathways can intersect, forming an integrated and purposeful network of chemical reactions “The Metabolic Map”

  10. A knowledge of normal metabolism is essentialfor an understanding of abnormalities underlying disease. • Normalmetabolism includesadaptation to periods of starvation, exercise, pregnancy, and lactation. • Abnormalmetabolism may result from  @ nutritional deficiency, @ enzymedeficiency, @ abnormal secretion of hormones, or the actions of @ drugsand @ toxins. • An important example of a metabolic diseaseis diabetes mellitus (DM).

  11. A metabolic pathway involves the step-by-step modification of an initial molecule to form another product. • The resulting product can be used in one of three ways: • To be usedimmediately, as the end-product of a metabolic pathway • To initiateanother metabolic pathway, called a flux generating step • To be stored by the cell • A molecule called a substrateenters a metabolic pathway depending on the needs of the cell and the availability of the substrate.

  12. Used product Substrate Stored Converted

  13. In humans, the most important metabolic pathways are: • Glycolysis glucose oxidation in order to obtain ATP • citricacidcycle (Krebs' cycle)  acetyl-CoA oxidation in order to obtain GTP(ATP) and valuable intermediates. • oxidativephosphorylation disposal of the electrons released by glycolysis and citric acid cycle. Much of the energy released in this process can be stored as ATP. • pentosephosphatepathway - synthesis of pentoses and release of the reducingpower (NADPH+H) needed for anabolic reactions.

  14. Metabolic pathways interact in a complex way in order to allow an adequate regulation. • This interaction includes • enzymaticcontrol of each pathway, • hormonecontrol. • 3. each organ's metabolic profile

  15. ATP = energy currency of the cell • It serves as the driving force for nearly all biochemical processes • ATP + H2O   ADP +Pi • The free energy liberated in the hydrolysis of ATP is used to drive the endergonic reactions • ATP is formed from ADP and Pi when fuel molecules are oxidized • This ATP-ADP cycle is the fundamental mode of energy exchange in biological systems

  16. Mechanisms for ATP Formation • Substrate Level Phosphorylation • Oxidative Phosphorylation • (in Mitochondrial Electron Transport chain) • every NADH+H+  gives3 ATP • every FADH2  gives2 ATP

  17. Remember

  18. Metabolismis the sum of all biochemical pathways that occur inside the cells. • Catabolismis a convergent process that provides energy to cells in the form of ATP. • Anabolismis a divergent process that consumes energy for the synthesis of complex molecules. • Metabolic pathways are tightly regulated and highly integrated. • ATP is the energy currency of the cells

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