Question

1. Discuss the four fates of pyruvate (one to CAC cycle). 2. Discuss the 10 steps of glycolysis including structures, cofactors, enzymes, irreversible steps and committed steps. 3. Discuss the regulation of glycolysis including ATP, AMP, ADP, and F2,6 BPG. 4. The three bypass steps (4 total) for gluconeogenesis 5. How do insulin, glucagon and epinephrine regulate glycogen synthesis and degradation? 6. PPP pathway: the stage I, the stoichiometry of step II and the enzymes 7. The four scenarios of PPP regulation: 1) need NADPH only; 2) need R5P only; 3) need both; 4) need NADPH and ATP.

Answer 1

9.1 Fates of Pyruvate : - Pyruvate, the product of glycolysis represent an important Junction point in Carbohydrate metabolism. - fate of pyruvate is decided under two conditions, ine.. 1) Aerobic 2) Anacrebie. 0 In Aereobic condition : - Fate I) In aerobic condition, pyruvate is treansported to mitochondria of the cell where it enters the TCA cycle, Then via ETC energy is generated. . To undergo this process, pyruvate is converted into acetyl coa in the matrix of mitochondria. Fate I ] Pyruvate may also be converted to oxaloautate, which also enters the TCA cycle to generate energy. Pyewate undergoes a carboxylation reaction to form oxaloacetate by the help of the enzyme pyreate carboxylase. This process is necessary to reeplenish the intermediates of the TCA cycle and provide Substrate for gluconeogenesis HCozt ADP+Pi Aspartate wia transamination) Pyruvatel Toxalo acetate Pyrevate Сомоохід. → Citrate (TCA cycle) > phosphoenol pyrwate (gluconeogenesis) Scanned with: CamScanner

Fate in cells, ferment @ In anaerobi Condion :- Fate m m anaerobic condition, Fermentation occurs. on yeast cells, fermentation occurs in two steps. First, pyruvate is converted to cretaldehyde by the enzyme pyruvate decarboxylase. second, Acetaldehyde is then converted to ethanol via alcohol dehydrogenase QNADH RNAD [2 pyswate] pyruvate 12 e = 2 Ethanol t decarboxylase Acetaldehyde deltagenare. Н Alcohol Fate The muscle cells and certain bacterial species uses NADH by transforming pyruvate into lactate and the process is known as lactic acid fermentation. dactic acid Fermentation. is catalysed by an enzyme dactate dehydrogenase. ZNADH QNADA Ta Pyrivate 12 Lactate Lactate cs Scanned with dehydrogenase. CamScanner

② Glycolyes is an oxidative process where one mole of glucose is partially oxidised to two moles of Pyruvate in an series of enzyme catalysed reactions. It occurs in the cytosol of the wil. - GHhOH Glucose (6) phosphorylation Hexokenase ATP mg2+ ADP. Step-1 HOP Step 2 Isomerization Blucose-6-phosphate G6P) phosphogluco- isombrase o choy Fructose-6-phosphate (F6P) OH Step3 . phosphorylation phosphofrueto Kinase LATP YADP maar CHOP Fruelose-1,6- Prisphosphate FBP) 1. OHOH Step-4. Cleavage Aldolase Zat On [Glyceraldehyde - 3-phosphate (G3P)] Porc-CH-CHO Step-5 Isomerization. Triose phosphate 11 somerase cs Scanned with Dihydkory acetone phosphate horec - Crop CamScanner

애 Step-6 oxidation ZNAD 4 tant a Glyceraldebydle - 3-phosphatel POHC-Ćy-440 530 1 QMADI TOP; dehydrogenase Ganad"tant *] 1, 9 - bisphosphoglycerat (DPC) Poyc-*- op phosphoglycorate 1 , 2 App ОН Step 7 клас QATP phosphate. 2 | 3 – phoghoglycrate (EPG)] poxc-**-.-.- Steps 9somerization phosphoglycerate mutase step-q dehydration mo at the OP a 2.- plkaiploggerate Cero] horyc-FH-E--- Ensement HD of phosphoenol pyzuvate (PEP) me = < _-o- step-10 . Pyruvate Kinase , QAPP phosphate Estar Hydrolylesi o 207P Syntherm of 2 (Pyruvate ATP. Here step 1, 3 a 10 are irreversible steps and others most committed step is Step 8 (Phosphofructokinase). Scanned with CamScanner

Plan Q-3 Regulation of Glycolysis The reate at which the glycolytic pathway operates controlled mainly by allosferic regulation of three enzymes. - hexokinase. - phosphofructokinase. - Pyruvate kinare. - The reactions catalysed by these enzymes are irreversible. Enzyme Activator Inhibitor Hexokinase Glucose-6-phosphate phosphofructokenase fructose-2, 6-bisphosphate Citrate, ATP. Fructose-6-phosphate, Amp. Pyruvate fructose-1, 6; bisphosphate. Acetyl coA . ATP. Kinase. E Amp. Scanned with CamScanner