A.Coupled reactions The additivity of free energy changes allows an endergonic reaction to be driven by an exergonic reaction under the proper conditions. (thermodynamic basis for the operation of the metabolic pathways since most of these reaction sequences comprise endergonic as well as exergonic reactions.

- Also known as Respiration. - Comprises of these different processes depending on type of organism: I. Anaerobic Respiration II. Aerobic Respiration

Comprises of these stages:  glycolysis: glucose 2 pyruvate + NADH  fermentation: pyruvate lactic acid or ethanol  cellular respiration:

Comprises of these stages:  Oxidative decarboxylation of pyruvate  Citric Acid cycle  Oxidative phosphorylation/ Electron Transport Chain(ETC)

STARCHY FOOD α – AMYLASE ; MALTASES Glycolysis in cytosol Brief overview of catabolism of glucose to generate energy Glucose converted to glu-6-PO 4 Start of cycle 2[Pyruvate+ATP+NADH] - Krebs Cycle - E transport chain Aerobic condition; in mitochondria Anaerobic condition Lactic Acid fermentation in muscle. Only in yeast/bacteria Anaerobic respiration or Alcohol fermentation Pyruvate enters as AcetylcoA Glucose Cycle : anaerobic

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 1 st stage of glucose metabolism → glycolysis  An anaerobic process, yields 2 ATP (additional energy source)  Glucose will be metabolized via gycolysis; pyruvate as the end product  The pyruvate will be converted to lactic acid (muscles → liver)  Aerobic conditions: the main purpose is to feed pyruvate into TCA cycle for further rise of ATP

Fig. 17-1, p.464 The breakdown of glucose to pyruvate as summarized: Glucose (six C atoms) → 2 pyruvate (three C atoms) 2 ATP + 4 ADP + 2 Pi → 2 ADP + 4 ATP (phosphorylation) Glucose + 2 ADP + 2 Pi → 2 Pyruvate + 2 ATP (Net reaction)

Fig. 17-2, p.465

Louis Pasteur - French biologist - did research on fermentation which led to important discoveries in microbiology and chemistry

p.467 Step 1Glucose is phosphorylated to give gluc-6-phosphate Preparation phase

Fig. 17-3, p.468

Table 17-1, p.469

Fig. 17-4, p.470

p.470a Step 2 Glucose-6-phosphate isomerize to give fructose-6- phosphate

p.470b Step 3Fructose-6-phosphate is phosphorylated producing fructose-1,6-bisphosphate

Fig. 17-6, p.471

p.471a Step 4Fructose-1,6-bisphosphate split into two 3-carbon fragments

p.471b Step 5Dihydroxyacetone phosphate is converted to glyceraldehyde-3-phosphate

p.472 Step 6 Payoff phase Glyceraldehyde-6-phosphate is oxidized to 1,3-bisphosphoglycerate

Fig. 17-7, p.473

p.474a

Fig. 17-8, p.475

p.476 Step 7Production of ATP by phosphorylation of ADP

p.477a Step 8Phosphate group is transferred from C-3 to C-2

p.477b Step 9 Dehydration reaction of 2-phosphoglycerate to phosphoenolpyruvate

p.478 Step 10Phosphoenolpyruvate transfers its phosphate group to ADP → ATP and pyruvate

Fig , p.479 Control points in glycolysis

p.479 Conversion of pyruvate to lactate in muscle

Fig b, p.481

Fig a, p.481 Pyruvate decarboxylase

Fig , p.482

p.482 Acetaldehyde + NADH → Ethanol + NAD + Glucose + 2 ADP + 2 P i + 2 H + → 2 Ethanol + 2 ATP + 2 CO H 2 O

Carbohydrate metabolism

Gluconeogenesis Conversion of pyruvate to glucose Biosynthesis and the degradation of many important biomolecules follow different pathways There are three irreversible steps in glycolysis and the differences bet. glycolysis and gluconeogenesis are found in these reactions Different pathway, reactions and enzyme p.495 STEP 1

is the biosynthesis of new glucose from non-CHO precursors. this glucose is as a fuel source by the brain, testes, erythrocytes and kidney medulla comprises of 9 steps and occurs in liver and kidney the process occurs when quantity of glycogen have been depleted - Used to maintain blood glucose levels. Designed to make sure blood glucose levels are high enough to meet the demands of brain and muscle (cannot do gluconeogenesis). promotes by low blood glucose level and high ATP inhibits by low ATP occurs when [glu] is low or during periods of fasting/starvation, or intense exercisefastingstarvationexercise pathway is highly endergonicendergonic *endergonic is energy consumingendergonic

STEP 2

The oxalocetate formed in the mitochondria have two fates: - continue to form PEP - turned into malate by malate dehydrogenase and leave the mitochondria, have a reaction reverse by cytosolic malate dehydrogenase Reason?

Fig , p.502 Controlling glucose metabolism found in Cori cycle shows the cycling of glucose due to gycolysis in muscle and gluconeogenesis in liver As energy store for next exercise This two metabolic pathways are not active simultaneously. when the cell needs ATP, glycolisys is more active When there is little need for ATP, gluconeogenesis is more active

Cori cycle requires the net hydrolysis of two ATP and two GTP.

Fig , p.503

The Citric Acid cycle Cycle where 30 to 32 molecules of ATP can be produced from glucose in complete aerobic oxidation Amphibolic – play roles in both catabolism and anabolism The other name of citric acid cycle: Krebs cycle and tricarboxylic acid cycle (TCA) Takes place in mitochondria

Fig. 19-2, p.513

Fig. 19-3b, p.514 Steps 3,4,6 and 8 – oxidation reactions

5 enzymes make up the pyruvate dehydrogenase complex: pyruvate dehydrogenase (PDH) Dihydrolipoyl transacetylase Dihydrolipoyl dehydrogenase Pyruvate dehydrogenase kinase Pyruvate dehydrogenase phosphatase Conversion of pyruvate to acetyl-CoA

p.518 Step 1 Formation of citrate

Table 19-1, p.518 Step 2 Isomerization

Fig. 19-6, p.519 cis-Aconitate as an intermediate in the conversion of citrate to isocitrate

Fig. 19-7, p.521 Step 3 Formation of α- ketoglutarate and CO 2 – first oxidation

p.521 Step 4 Formation of succinyl-CoA and CO 2 – 2nd oxidation

p.522 Step 5 Formation of succinate

p.523a Step 6 Formation of fumarate – FAD-linked oxidation

p.524a Step 7 Formation of L-malate

p.524b Step 8 Regeneration of oxaloacetate – final oxidation step

Fig. 19-8, p.526 Krebs cycle produced: 6 CO 2 2 ATP 6 NADH 2 FADH 2

Table 19-3, p.527

Fig , p.530

Fig , p.531

Fig , p.533

Fig , p.535

Overall production from glycolysis, oxidative decarboxylation and TCA: Oxidative decarboxylation GlycolysisTCA cycle -2 ATP 2 NADH 6 NADH, 2 FADH 2 2 CO 2 2 Pyruvate4 CO 2 Electron transportation system