Presentation on theme: "BC368: Biochemistry of the Cell II Citric Acid Cycle Chapter 16 March 12, 2015."— Presentation transcript:
BC368: Biochemistry of the Cell II Citric Acid Cycle Chapter 16 March 12, 2015
3 stages of respiration Production of acetyl-CoA (e.g., during glycolysis and the bridging reaction) Oxidation of acetyl-CoA via the citric acid cycle Electon transport and oxidative phosphorylation to produce lots of ATP Fig 16-1
Glycolysis takes place in the cytosol The citric acid cycle takes place in the mitochondrial matrix Mitochondrial Architecture
Succinyl-CoA synthetase reaction Hydrolysis of CoA-SH drives phosphorylation of succinate within the enzyme-substrate complex Succinate transfers its phosphate group to the enzyme Enzyme phosphorylates GDP
Anaplerotic Reactions Example: pyruvate carboxylase, which uses a biotin (vitamin B7) cofactor to carry CO 2
Daniel plans to enter the Mr. Colby contest and wants to get jacked. He has begun adding raw eggs to his diet and is up to a dozen a day. Unfortunately, he has been experiencing lactic acidosis during his weight training and hypoglycemia between meals. What’s up with Daniel? Case Study
Pyruvate carboxylase Carboxyl group of bicarbonate is “activated” by phosphorylation
Pyruvate carboxylase “Activated” CO 2 is passed to biotin cofactor with loss of Pi
Pyruvate carboxylase CO 2 is passed to second active site for rxn with pyruvate
CO 2 is released for reaction with pyruvate to form OA. Pyruvate carboxylase
Glyoxylate cycle Fig 16-22 Plants and some microorganisms can convert acetyl-CoA to oxaloacetate for net gain of carbon and net synthesis of TCA intermediates
Intersection with TCA Fig 16-24 Glyxoylate pathway runs simultaneously with TCA but in a different compartment.
Coordinated regulation Fig 16-25 Isocitrate is a branch point; its fate depends on relative activities of isocitrate dehydrogenase (TCA) and isocitrate lyase (glyoxylate cycle).
Vania can’t believe that she feels so lousy. Even though it is St. Patrick’s Day weekend and she’s been up all night partying, she’s never felt this bad before. Her head is pounding, and she feels tired, weak, dizzy, and sick to her stomach. She would drink some water, but she lost her Nalgene bottle last week somewhere, and the walk to the dining hall is just way too far. Case Study 1. What is wrong with Vania? 2. What are the consequences of dehydration on metabolism? 3. What are the metabolic breakdown products of ethanol? 4. What role do these metabolic products play in the citric acid cycle? 5. What would you recommend to Vania?