L13 - Krebs Cycle Topics Krebs Cycle Krebs Cycle Acetyl Co...

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Unformatted text preview: Krebs Cycle Topics Krebs Cycle Krebs Cycle Acetyl Co A and FADH 2 Amphibolic & Anapleurotic Precursors for lipid, amino acid, nucleotide synthesis Using metabolism to make products to make $$$$ 1 The Important (Exam) Stuff Describe and explain energy transmission compounds Acetyl CoA and FADH 2 Describe and explain Krebs Cycle substrates, energy products and carbon flow. Explain how Glycolysis and Krebs Cycle intermediates create key anabolic precursors. Describe the Glyoxalate Bypass and explain how commercial products created exploiting it. Back to the Map Glycolysis Krebs Cycle Fermentation ETC NADH ATP Carbon Flow 2 What is a Krebs Cycle? Discovered by Sir Hans Krebs Nobel Prize 1953 aka citric acid (CAC) or tricarboxylic acid (TCA) cycle 2nd stage of glucose metabolism Occurs in many microbes Occurs without O but usually found in 2 , microbes that require oxygen for metabolism Includes substrate level phosphorylation (again) Involves different energy transmission compounds CoenzymeA & Derivatives Function as acyl carriers transfer acetyl and thiol groups CoenzymeA Succinyl CoenzymeA Acetyl CoenzymeA Acetyl MEA Pantothenic acid 3phospho ADP Growth factor Pantothenate 3 FAD and FADH (Son of NADH) 2 C to C (via C and C ) 3 4 2 6 CoA NAD+ pyruvate ~CoA CO 2 CoA aka Thiamine Pyruvate dehydrogenase NADH oxaloacetate NAD+ acetylCoA citrate isocitrate NADH CoA NAD+ CO 2 alpha ketoglutarate CO 2 ~CoA succinyl CoA NADH 4 C to C 4 (and back again) 4 ADP + Pi ~CoA CoA succinyl CoA ATP FAD succinate FADH 2 fumarate malate oxaloacetate Combines with AcetylCoA To begin the cycle again... NAD+ NADH Krebs/TCA/Citric Acid Cycle acetyl~CoA oxaloacetate ~CoA ~CoA malate ~CoA glyoxylate citrate fumarate isocitrate CO 2 succinate a ketoglutarate ~CoA ~CoA succinyl~CoA ~CoA CO 2 5 Krebs Cycle Overview Glycolysis Krebs Cycle Invest: 1 pyruvate, 1 Acetyl CoA x 2(Glucose) Harvest: 4 NADH. 1 ATP, 1FADH , 3 CO x 2(Glucose) 2 2 Nucleotide Biosynthesis Glucose 6 phosphate Glycolysis Pentose Phosphate Pathway (5C) DHAPG3P oxaloacetate Glycine Pentoses Purines Pyrimidines Krebs Cycle a ketoglutarate Aspartate Glutamine Purines Adenine (DNA & RNA) Guanine (DNA & RNA) Pyrimidines Cytosine (DNA & RNA) Thymine (DNA only) Uracil (RNA only) 6 Protein catabolism & Amino Acid synthesis Outside Amino Acid Families Inside Glucose 6 phosphate Aromatic Family Amino acids Amino acids Amino acids G3P Serine Family Alanine Family Protein Amino acids Amino acids Aspartate Family Alpha ketoglutarate Amino acids Glutamate Family Catabolism Anabolism Lipid Metabolism Outside Inside DHAPG3P Glycerol Lipids Fatty Acids Fatty Acids Glycerol Lipids Catabolism Anabolism G3P & Acetyl CoA can be oxidized for energy used or lipid precursors. 7 Anaplerotic Pathways: Example: Glyoxylate Bypass Anapleurotic means "filling" Reactions that supplement losses due to extra or alternative biosynthesis. Example: The Glyoxylate cycle provides carbon for microbes that fix CO or use lipids or 2 carbon sources for energy. 2 The Glyoxylate cycle, or bypass, avoids CO loss from standard 2 Krebs cycle reactions and allows for the synthesis of oxaloacetate from AcetylCoA and glyoxalate. The Glyoxylate Bypass acetyl~CoA oxaloacetate ~CoA Excess CO2 ~CoA Limiting CoA citrate malate ~CoA glyoxylate fumarate isocitrate CO 2 succinate ~CoA ~CoA succinyl~CoA ~CoA a ketoglutarate CO 2 WHY? 8 Monosodium Glutamate MSG The total market value for amino acids was estimated to be $3.5 billion ( 2.68bn) in 2004. Lysine and monosodium glutamate (MSG) are the largest sectors of this market. Corynebacterium glutamicum Lots of Biotin & CO 2 Lots of Biotin & CO 2 9 Where to Next? Glycolysis Krebs Cycle Fermentation ETC NADH ATP Carbon Flow Text References th Pages 126132 (11 Edition) 10 ...
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This homework help was uploaded on 03/21/2008 for the course PY 211 / 212 taught by Professor Chilton during the Spring '08 term at N.C. State.

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