Essential Elements of Biochemistry BCHM 3050 Dr Srikripa Chandrasekaran Lecture 4 8 15 Notes Aerobic Respiration The Citric Acid Cycle I II III V The Citric Acid Cycle A Also called tricarboxylic cycle tricarboxylic molecule is used and citric acid cycle citric acid is the compound that is regenerated Summary Reaction A Pyruvate is a 3 carbon atom containing molecule B 2 molecules of pyruvate at start C 4 NADH 1 FADH2 3 CO2 GTP are the products of this reaction D Enzyme converts pyruvate into acetyl coA which carries out the Kreb s cycle pyruvate itself doesn t actually carry out the Kreb s cycle E Pyruvate dehydrogenase is the enzyme that catalyzes the step before F the start of the Kreb s cycle Inside of the mitochondria is the matrix where pyruvate dehydrogenase is found pyruvate processing pyruvate loses 2 CO2 forming acetyl coA 2 molecules of NADH formed G Start with 6 carbon glucose in glycolysis all carbon atoms are broken down and released at 6 CO2 molecules Review of Mitochondrial Ultrastructure A Thought to originally have been a prokaryote B Mitochondria has its own DNA C Krebs cycle and pyruvate processing occur in the matrix D Cristae folds is the same thing as the inner membrane E PDH pyruvate dehydrogenase complex is found on the inner member matrix IV Overview of the TCA Cycle A Know how many carbon atoms are present in each state when CO2 NADH FADH ATP ADP are all released B Pyruvate is going to become completely oxidized into CO2 C Substrate level phosphorylation 1 ATP after each round of Krebs so 2 ATPs once both pyruvates have gone through the cycle D 3 carboxylic acid groups in citric acid Enzymes of the TCA Cycle A All circled numbers indicated an enzyme used in the cycle B Enzymes labeled in yellow show where NADH or FADH2 are created C Step 1 Occurs in mitochondria matrix loses CO2 generates NADH oxidation reduction reaction pyruvate dehydrogenase belongs to the category of oxioreducatase enzymes D CoA 2 carbon atoms E Isocitrate 6 carbon atoms 1 F Whenever you make an NADH enzyme is a dehydrogenase G Succinyl CoA synthetase converts succinyl coA to succinate only one that does substrate level phosphorylation to create ATP in this cycle H Succinate fumarate generates FADH2 oxioreducatase I Break down bond of fumerate using water to created malate break in the presence of water is hydrolase J Malate oxaloacatate generate NADH oxioreductase Pyruvate Dehydrogenase A Pyruvate dehydrogenase converts pyruvates to acetyl coenzyme A B This is the first enzyme in the Kreb s cycle Pyruvate Dehydrogenase Complex Components Regulation A This is a 3 step reaction B Do not worry about the exact number of copies for each enzyme C Know the names of the enzymes co factors functions but not of D Someone with vitamin B deficiency does not make TPP cannot carry copies out respiration very well VIII Two Modes Regulation of the Pyruvate Dehydrogenase Complex A Allosteric regulation is heavily regulated B ATP is a universal inhibiter for glycolysis and the Kreb s Cycle C Right at the beginning of glycolysis step 1 the product glucose 6 phosphate inhibits the enzyme hexokinase D The product acetyl coA in the Kreb s Cycle inhibits the enzyme pyruvate dehydrogenase complex Insulin will dephosphorylate while glucagon will phosphorylate E F Glucose 6 phosphate can inhibit hexokinase product inhibits enzyme in step 1 for glycolysis G Acetyl coA product inhibits enzymes just like step 1 of glycolysis H Pyruvate dehydrogenase can be inactivated by phosphorylation I last enzyme in glycolysis pyruvate kinase is inhibited by phosphorylation Citrate Synthase A When acetyl CoA inhibits glucose 6 phosphate then it activates citrate synthase B An enzyme that gets activated by its substrate is phosphofructokinase1 ATP activates it and is also its substrate C For citrate synthase the substrates activate it D Enzyme is inhibits by its substrate ATP inhibits phosphofructokinase 1 yet ATP also serves as its substrate E Succinyl coA is a downstream inhibitor F Acetyl coA and OAA stimulate Succinate Dehydrogenase A This enzyme sits in the inner membrane rather than the matrix which is where most of the enzymes are located VI VII IX X 2 B The only enzyme that is activated by ATP rather than inhibited is succinate dehydrogenase this is because it is part of the electron transport chain C Succinate dehydrogenase sits in the inner membrane and is part of the complex in the electron transport chain D ATP activates in this step rather than inhibiting like all of the other processes 3
View Full Document
Unlocking...