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Introduction to Metabolism. Objectives Understand the concept of metabolic pathway Understand the concept of metabolic pathway Identify types & characters.

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Presentation on theme: "Introduction to Metabolism. Objectives Understand the concept of metabolic pathway Understand the concept of metabolic pathway Identify types & characters."— Presentation transcript:

1 Introduction to Metabolism

2 Objectives Understand the concept of metabolic pathway Understand the concept of metabolic pathway Identify types & characters of metabolic pathways- anabolic and catabolic Identify types & characters of metabolic pathways- anabolic and catabolic Identify ATP as the energy currency of cells Identify ATP as the energy currency of cells Understand the transport of major metabolic fuel- Glucose Understand the transport of major metabolic fuel- Glucose

3 Metabolism All the chemical reactions taking place inside a cell are collectively known as METABOLISM All the chemical reactions taking place inside a cell are collectively known as METABOLISM

4 Metabolism Metabolic Pathways are chemical reactions organized in multisteps sequences where: Metabolic Pathways are chemical reactions organized in multisteps sequences where: The product of one reaction of the pathway serves as substrate of the subsequent reaction The product of one reaction of the pathway serves as substrate of the subsequent reaction Most pathways can be classified as anabolic (synthetic) or catabolic (degenerative) Most pathways can be classified as anabolic (synthetic) or catabolic (degenerative) Integrated pathways= Metabolism Integrated pathways= Metabolism

5 Glycolysis, an example of a metabolic pathway

6 Basic functions of metabolism 1. To obtain energy from fuel molecules 2. To convert nutrients into precursors of cellular components. 3. To assemble precursors utilizing energy into cellular components.

7 ANABOLIC CATABOLIC ANABOLIC CATABOLIC BiosyntheticDegradative ReductiveOxidative Energy RequiredEnergy Liberated DivergingConverging Decomposition of large complex molecules into small molecules large complex organic molecules are constructed from small molecules

8 Catabolism Many Few Anabolism Few Many (converging) (diverging)

9 Catabolic Pathway

10 Anabolic Pathway Combine small moles as a.a. to form complex as ptn Combine small moles as a.a. to form complex as ptn It is a divergent process w needs ATP (endergonic) & reducing power (mostly NADPH) It is a divergent process w needs ATP (endergonic) & reducing power (mostly NADPH)

11 Nutrients Carbohydrates Fats Proteins End products H 2 O, CO 2, NH 3 exergonic Catabolism (oxidative, exergonic) Macromolecules Proteins Polysaccharides Lipids Nucleic acids Precursor Molecules Amino acids Sugars Fatty acids Nitrogenous bases endergonic Anabolism (reductive, endergonic) Chemical energy ATP NADPH GTP ATP NADH Catabolism and anabolism are always related.

12 Amphibolic Pathway Amphi = Dual, amphibolic: dual pathway Amphi = Dual, amphibolic: dual pathway For example, For example, Krebs cycle is mainly a catabolic cycle, but with some anabolic features, e.g., part of Krebs cycle is used for the synthesis of glucose from amino acids Therefore, Krebs cycle is amphibolic

13 Metabolic Map Different pathways can intersect, forming an integrated and purposeful network of chemical reactions The Metabolic Map Different pathways can intersect, forming an integrated and purposeful network of chemical reactions The Metabolic Map

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15 Chemical energy ATP - energy currency. It serves as the driving force for nearly all biochemical processes ATP - energy currency. It serves as the driving force for nearly all biochemical processes NADH,NADPH - reducing power. NADH,NADPH - reducing power. NADH for oxidation and energy yielding. NADH for oxidation and energy yielding. NADPH for biosynthetic processes NADPH for biosynthetic processes

16 ATP is the energy currency of the cell ATP + H 2 O ADP +P i The free energy liberated in the hydrolysis of ATP is used to drive the endergonic reactions The free energy liberated in the hydrolysis of ATP is used to drive the endergonic reactions ATP is formed from ADP and P i when fuel molecules are oxidized ATP is formed from ADP and P i when fuel molecules are oxidized This ATP-ADP cycle is the fundamental mode of energy exchange in biological systems This ATP-ADP cycle is the fundamental mode of energy exchange in biological systems

17 Δ Gº -7.3 kcal/mol/bond

18 E-rich compounds e.g., Oxidation E-rich reduced coenzymes ETC

19 Oxidation Oxidation: Loss of hydrogen Loss of electrons Reduction Reduction: Gain of hydrogen Gain of electrons Oxidation/Reduction

20 NAD/NADH

21 Metabolism Regulation

22 Intracellular Regulation Imp. for moment-to-moment regulation of metabolism which elicit rapid responses by: Imp. for moment-to-moment regulation of metabolism which elicit rapid responses by: availability of substrate availability of substrate product inhibition or product inhibition or alteration in the levels of allosteric activators or inhibitors alteration in the levels of allosteric activators or inhibitors

23 Intercellular Regulation Provides long-range integration of metabolism Provides long-range integration of metabolism Usually is slower than intracellular signals, it is done by : surface to surface Usually is slower than intracellular signals, it is done by : surface to surface the most important is the most important is chemical signaling by hormones or neurotransmitters chemical signaling by hormones or neurotransmitters This results in the production of second messengers This results in the production of second messengers

24 Metabolic Fuel Carbohydrates & lipids (mainly) and proteins (little extent) are used for energy production Carbohydrates & lipids (mainly) and proteins (little extent) are used for energy production These are- glucose, fatty acids and amino acids These are- glucose, fatty acids and amino acids Glucose is the major metabolic fuel of most tissues Glucose is the major metabolic fuel of most tissues

25 Na + -Monosaccharide Cotransporter : Against concentration gradient Energy dependent Carrier-mediated Coupled to Na + transport Small intestine, renal tubules & choroid plexus Na + -Independent Facilitated Diffusion: With concentration gradient Energy Independent Glucose Transporters (GLUT 1-14)

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27 Tissue-specific expression pattern GLUT-1 RBCs and brain GLUT-2Liver, kidney & pancreas GLUT-3Neurons GLUT-4Adipose tissue & skeletal muscle GLUT-5Small intestine & testes GLUT-7Liver (ER-membrane) Functions : GLUT-1, 3 & 4Glucose uptake from blood GLUT-2Blood & cells (either direction) GLUT-5Fructose transport

28 Take Home Message Metabolism is the sum of all biochemical pathways that occur inside the cells. Metabolism is the sum of all biochemical pathways that occur inside the cells. A metabolic pathway is a multistep sequences of enzyme-catalyzed reactions. A metabolic pathway is a multistep sequences of enzyme-catalyzed reactions.

29 Catabolism is a convergent process that provides energy to cells in the form of ATP. Catabolism is a convergent process that provides energy to cells in the form of ATP. Anabolism is a divergent process that consumes energy for the synthesis of complex molecules. Anabolism is a divergent process that consumes energy for the synthesis of complex molecules. Metabolic pathways are tightly regulated and highly integrated. Metabolic pathways are tightly regulated and highly integrated.

30 ATP is the energy currency of the cells ATP is the energy currency of the cells Glucose is transported in/out of the cells by: Glucose is transported in/out of the cells by: Energy-dependent active transport Energy-independent facilitated transport Energy-independent facilitated transport


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