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NS 315 Unit 4: Carbohydrate Metabolism

NS 315 Unit 4: Carbohydrate Metabolism. Dr. Rebekah S. Marsh Kaplan University. Unit 7: Exercise paper

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NS 315 Unit 4: Carbohydrate Metabolism

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  1. NS 315Unit 4: Carbohydrate Metabolism Dr. Rebekah S. Marsh Kaplan University

  2. Unit 7: Exercise paper Four hours ago, I ate 3 oz of baked chicken marinated in 1 tsp olive oil and other spices, 1 cup rice and ½ cup beans, 2 cups salad (romaine lettuce, carrots, onions and radishes) with 2 tablespoons ranch dressing and 1 cup of skim milk. Now, I am going to run for 45 minutes and will lift weights for another 30 minutes DUE: by EOD Tuesday 03/22/2011 • Are these activities considered aerobic, anaerobic or a combination of both? And why do you believe so based on the scenario above? • Based on the meal plan above, what foods contain carbohydrates, proteins and fats? • How are carbohydrates, proteins and fats digested and absorbed? • Which main pathway is utilized (glycolysis, gluconeogenesis, beta oxidation) when first starting to work out? What macronutrient does this pathway use and what are the end products? • Please explain beta oxidation and gluconeogenesis: what macronutrients they are utilizing, what the end products are and why they are needed while working out?

  3. Introduction to Carbohydrate Metabolism

  4. Key Terms • Anabolism: Assembly of complex organic molecules • Catabolism: Degradation of complex molecules • Heterotrophs: Synthesize their organic metabolites only from other organic compounds, which they consume

  5. Key Terms • Intermediary Metabolism: All reactions concerned with storing and generating metabolic energy and with using that energy in biosynthesis of low molecular weight compounds • Energy Metabolism: Pathways that store or generate metabolic energy

  6. Overview of Metabolism

  7. Three Stages of Metabolism ncbi.nlm.nih.gov

  8. The Major Metabolic Pathways http://staff.jccc.net/PDECELL/cellresp/simpleover.gif

  9. Biosynthesis & Degradative Pathways

  10. Carbohydrate Metabolism:Glycolysis and Gluconeogenesis

  11. Key Terms • Glycolysis: central pathway for the catabolism of carbohydrates; occurs in most organs • Glyconeogenesis: Biosynthesis of new glucose; occurs mainly in liver • Glycogenesis: group of enzymatic reactions leading to the formation of glycogen • Glycogenolysis: group of enzymatic reactions that use stored glycogen to form glucose

  12. Key Terms (continued) • Pyruvate: final 3 carbon molecule of glycolysis, involved in the Krebs cycle which facilitates energy production • Adenosine diphosphate (ADP) /Adenosine triphosphate (ATP): energy storing molecule used by an organism on a daily basis • Aerobic: in the presence of oxygen • Anaerobic: no presence of oxygen

  13. Glycolysis Animation Please review the website for an animated description of glycolysis pathway and we will discuss it in 5 minutes http://www.youtube.com/watch?v=x-stLxqPt6E Other good sites to review Glycolysis: http://www.cliffsnotes.com/WileyCDA/CliffsReviewTopic/Introduction-to-Glycolysis.topicArticleId-24998,articleId-24980.html http://www.dnatube.com/video/2338/Glycolysis

  14. Glycolysis http://www.accessexcellence.org/RC/VL/GG/ecb/ecb_images/13_01Glycolysis-Steps_1-5.jpg

  15. Fates of Pyruvate Under aerobic conditions In most aerobic organisms, pyruvate continues in the formation of Acetyl CoA and NADH that follows into the Krebs cycle and ETC Under anaerobic conditions Under anaerobic conditions, such as during exercise or in red blood cells (no mitochondria), pyruvate is reduced to lactate by lactate dehydrogenase producing NAD for glycolysis

  16. Gluconeogenesis http://themedicalbiochemistrypage.org/images/gluconeogenesis.jpg

  17. Gluconeogenesis 2 pyruvate + 2 NADH + 4 ATP + 2 GTP glucose + 2 NAD+ + 4 ADP + 2 GDP + 6 Pi • Synthesis of glucose from 3-4 carbon precursors is a reversal of glycolysis • 3 reactions in glycolysis are essentially irreversible, thus they are bypassed in gluconeogenesis: • Hexokinase (1) • Phosphofructokinase (3) • Pyruvate Kinase (10) • Share 7 of the 10 steps in glycolysis

  18. GlycolysisvsGluconeogenesis • Fasting state • Cytoplasm • Liver mostly, but also kidney • Fed state • Cytoplasm • All cells

  19. Carbohydrate Metabolism:Krebs Cycle and Electron Transport Chain

  20. Definitions • Krebs cycle - series of enzymatic reactions in aerobic organisms involving oxidative metabolism of acetyl units and producing high-energy phosphate compounds, which serve as the main source of cellular energy • Electron Transport Chain (ETC) - Composed of mitochondrial enzymes that transfers electrons from one transport to another, resulting in the driving force for the formation of ATP • Oxidative phosphorylation- Process occurring in the cell, which produce energy and synthesizes ATP

  21. Definitions • NAD/NADPH: Reducing agent in several anabolic reactions such as lipid and nucleic acid • FAD/FADH: Reducing agent in several anabolic reactions such as lipid

  22. Krebs Cycle 2 pyruvate + 2 GDP + 2 H3PO4 + 4 H2O + 2 FAD + 8 NAD+ 6 CO2 + 2 GTP + 2 FADH2 + 8 NADH • Also known as the citric acid cycle or tricarboxylic acid (TCA) cycle • Under aerobic conditions pyruvate enters the mitochondria MATRIX and is oxidized to Acetyl CoA which enters the Krebs cycle • Krebs cycle can occur after glycolysis, after Beta oxidation or protein degradation to provide energy for cellular respiration • Equation for Krebs cycle with the beginning products and the ending. 8 steps involved

  23. Krebs Cycle Please go to:http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_the_krebs_cycle_works__quiz_1_.htmland we will discuss the krebs cycle after the animated movie. Other sites for the Krebs Cycle: http://www.dnatube.com/video/2354/Electron-Transport-Chain http://www.elmhurst.edu/~chm/vchembook/596electransport.html

  24. Krebs Cycle (TCA) http://image.tutorvista.com/content/respiration/krebs-cycle.jpeg

  25. Summary TCA Occurs in the mitochondrial matrix Uses acetyl CoA to produce: 3 NADH, 1 FADH, 1 GTP, 2Co2 Produce intermediates for biosynthetic pathways such as amino acid synthesis, gluconeogenesis, pyrimidine synthesis, phorphyrin synthesis, fatty acid synthesis, isoprenoid synthesis.

  26. Electron Transport Chain (ETC) Final pathway by which electrons generated from oxidation of carbs, protein and fatty acids, are ultimately transferred to O2 to produce H2O Located in the inner mitochondrial membrane Electrons travel down the chain, pumping protons into the intermembrane space creating the driving force to produce ATP in a process called oxidative phosphorylation There are 4 complexes that comprise the ETC

  27. Electron Transport Chain Please go to: http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/oxidative/oxidativephosphorylation.html and we will discuss about the ETC after the animated film. Other help link to explain the ETC: http://www.stolaf.edu/people/giannini/flashanimat/metabolism/mido%20e%20transport.swf http://vcell.ndsu.edu/animations/etc/movie.htm

  28. Electron Transport Chain http://vcell.ndsu.nodak.edu/animations/etc/Stills/0917.jpg

  29. Summary ETC Reduced electron carriers NADH & FADH2 reduce O2 to H2O via the ETC. The energy released creates a proton gradient across the inner mitochondrial membrane. The protons flow down this concentration gradient back across the inner mitochondrial membrane through the ATP Synthase. The driving force makes this enzyme rotate and this conformation generates enough energy to produce ATP. Oxidation of NADH to NAD+ pumps 3 protons which charges the electrochemical gradient with enough potential to generate 3 ATPs. Oxidation of FADH2 to FAD+ pumps 2 protons which charges the electrochemical gradient with enough potential to generate 2 ATPs.

  30. Oxidative Phosphorylation http://stevebambas.com/images/AP%20220%20ox%20phosph.jpg

  31. References Introduction to Carbohydrate Metabolism • Mathews C & Van Holde K. (1990). Biochemistry. Redwood City: The Benjamin/Cummings Carbohydrate Metabolism • King, M (2010). Digestion of Dietary Carbohydrates. Retrieved on May 13, 2010 from http://themedicalbiochemistrypage.org/glycolysis.html • Hardy, J (2003). Gluconeogenesis. Retrieved on May 13, 2010 from http://www.elmhurst.edu/~chm/vchembook/604glycogenesis.html • Campbell, Neil A. (2005) AP Edition Biology. 7th. San Francisco, CA: Pearson Benjamin Cummings Carbohydrate Metabolism: Krebs Cycle and Electron Transport Chain • Phases of the Krebs Cycle (N.D.) Retrieved on May 13, 2010 from http://incolor.inebraska.com/mcanaday/Krebs%20Phases.htm • Electron Transport Chain (N.D.) Retrieved on May 13, 2010 from http://vcell.ndsu.edu/animations/etc/movie.htm • Campbell, Neil A. (2005) AP Edition Biology. 7th. San Francisco, CA: Pearson Benjamin Cummings

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