Lecture 1 (1).pptx

Main Metabolic Pathways By: Dr. Dilini Sadeepa Date: 08/07/2024 Metabolism What is Metabolism…….? The sum of reactions needed to support the life of an organism Cellular Respiration Bio synthesis Energy for; Movement...

Main Metabolic Pathways By: Dr. Dilini Sadeepa Date: 08/07/2024 Metabolism What is Metabolism…….? The sum of reactions needed to support the life of an organism Cellular Respiration Bio synthesis Energy for; Movement Growth and development Reproduction How do living organisms or, their cells extract energy from their environments How do cells use this energy to synthesize and assemble the components from which the cells are made  Metabolism Catabolism Anabolism Breakdown of Synthesis of new, compounds large compounds Release energy Absorb energy Cellular Photosynthesis respiration Synthesis of Glycolysis polymer Phosphorylati on Metabolism Metabolism Cellular Respiration 1.Glycolysis 2.Kreb’s Cycle 3.Electron Transport System Energy carriers  ATP:  ATP consists of a molecule of adenosine (adenine + ribose) to which three phosphate groups are attached  Removal of one phosphate produces adenosine diphosphate (ADP), and removal of two phosphates produces adenosine monophoaphate (AMP)  ATP is called a high energy phosphate compound ATP: An energy carrier  Energy carriers NADH (nicotinamide adenine dinucleotide) NADPH (Nicotinamide adenine dinucleotide phosphate) FADH (flavin adenine dinucleotide) ↓ Important carrier molecules that carry high energy electrons  Cellular Respiration 1. Glycolysis 2. Kreb's cycle 3. Electron transport chain Glycoly sis Glycoly The glycolytic pathway is used by all sis tissues for the oxidation of glucose to provide energy (as ATP) and intermediates for other metabolic Glycolysis is a fundamental process to a living pathways organism It is a rapid process which releases energy from glucose It is regulated by a sophisticated mechanism, where metabolic and hormonal control interact It provides substrates for the TCA cycle where much more ATP can be generated  In glycolysis, the 6-carbon sugar, glucose, is broken down into two molecules of a 3-carbon molecule called pyruvate This change is accompanied by a net gain of 2 ATP molecules and 2 NADH molecules Glycolysis takes place in the cytoplasm of cells Kreb’s Cycle Electron Transport System https://www.youtube.com/watch?v=imVyaPkC3Vc Cellular Respiration Summary of Cellular Respiration This will happen with oxygen.. What will happen without oxygen..? Fermentation Lipid Metabolism Fatty Pathway  Lipids are a heterogeneous group of water- insoluble (hydrophobic) organic molecules that can be extracted from tissues by non-polar solvents  The oxidation of long-chain fatty acids to acetyl- CoA is a central energy-yielding pathway in many organisms and tissues  The acetyl-CoA produced from the fatty acids may be completely oxidized to CO2 in the citric acid cycle, resulting in further energy conservation  In liver, acetyl-CoA may be converted to ketone bodies—water-soluble fuels exported to the brain and other tissues when glucose is not available Fatty Pathway Fatty Pathway Fatty Pathway Fatty Pathway Fatty Pathway Entry of glycerol into the glycolytic pathway Mobilization of triacylglycero ls stored in adipose tissue  Mobilization of triacylglycerols stored in adipose tissue Mobilization of triacylglycerols stored in adipose tissue. When low levels of glucose in the blood trigger the release of glucagon, 1) the hormone binds its receptor in the adipocyte membrane and thus 2) stimulates adenylyl cyclase, via a G protein, to produce cAMP. This activates PKA, which phosphorylates 3) the hormone-sensitive lipase and 4) perilipin molecules on the surface of the lipid droplet. Phosphorylation of perilipin permits hormone sensitive lipase access to the surface of the lipid droplet, where 5) it hydrolyzes triacylglycerols to free fatty acids. 6) Fatty acids leave the adipocyte, bind serum albumin in the blood, and are carried in the blood; they are released from the albumin and 7) enter a myocyte via a specific fatty acid transporter. 8) In the myocyte, fatty acids are oxidized to CO2, and the energy of oxidation is conserved in ATP, which fuels Glycogen Metabolism  Glycogen Metabolism A constant source of blood glucose is an absolute requirement for human life Body has developed mechanisms for storing a supply of glucose in a rapidly mobilized form, namely, glycogen. In the absence of a dietary source of glucose, this sugar is rapidly released into the blood from liver glycogen Similarly, muscle glycogen is extensively Glycogen Metabolism Ingestion of a carbohydrate-rich meal Blood glucose exceeds the usual concentration between meals Insulin released from the pancreas Blood glucose triggers the movement glut4 molecules Excess glucose is taken up by the myocytes of cardiac and skeletal muscle Glycogen Synthesis Glycogenolysis & Glycogenesis Gluconeogenesis Gluconeogene sis Synthesis of Glucose from non-carbohydrate precursors (de novo synthesis) What is gluconeogenesis? “Synthesis of glucose from non-carbohydrate precursor molecules” Where does gluconeogenesis occur? Mainly in the liver Limited extent in the kidney and small intestine The brain, skeletal muscles, heart muscles Other body tissue. These organs have a high demand for glucose. Gluconeogenesis  Synthesis of glucose from pyruvate utilizes many of the same enzymes as Glycolysis with the exception of enzymes of the irreversible steps namely,  Hexokinase  Phosphofructokinase  Pyruvate Kinase  The irreversible reactions of glycolysis are bypassed by four alternate unique reactions of gluconeogenesis catalysed by,  pyruvate carboxylase  phosphoenolpyruvate (PEP) carboxykinase  fructose 1,6-bisphosphatase  glucose 6-phosphatase Thank you! Any Questions……….? Contact: [email protected]