Glucose Metabolism 9.10

1. The point is to make ATP 2. Moving H-atoms…..moves energy from one molecule to another 3. Oxidation/ReductionOIL RIG *Coupled ReactionsLEO GER Oxidized?Reduced? RESPIRATION: Process by which cells generate ATP through a series of redox reactions. Converting food energy* (C 6 H 12 O 6 ) into ATP. *Need ATP for some coupled reactions… (*Proteins, Lipids, Nucleic acids, Other Carbohydrates). Glucose Oxygen

1. GLUCOSE is Broken down 2. Occurs in steps 3. Bond energy is released as ATP + HEAT 4. Small amounts of energy released at each step…controlled by enzymes (reaction rate) 5. Occurs CONSTANTLY WHY IN STEPS?

FOUR STAGES (notes) * GLYCOLYSIS * FORMATION OF ACETYL CoA * CITRIC ACID (KREBS) CYCLE * ELECTRON TRANSPORT CHAIN Cellular Respiration Fermentation Mitochondria/ETC Cytosol/Cytoplasm

* Does NOT require oxygen (Can be aerobic or anaerobic) * Requires: ATP, ADP, NAD + * TWO PHASES: Endergonic & Exergonic “Investment - Capture” * 1 Glucose 2 pyruvate (2-3C) NET 2 ATP, 2 NADH

(2 G3P) *Oxidation of NAD+ to NADH 3 steps: Kinase: Phosphorylation of glucose *More chemically Active Isomerase (Glucose 6P to Fructose6P) Kinase: 2nd Phosphorylation Fructose6P to Fructose 1,6P) 2 more steps: Split, Isomerase One Step: Gain of H (NAD+ to NADH) Powers Gain of P i (Inorganic Phosphate) *Inorganic phosphate in cytoplasm Last 4 Steps: Kinase… Substrate Level Phosphorylation * ADP to ATP 5 steps

* NAD + + 2H H = e- p+ NAD + + e- = NAD + H (e- and p+) = NADH “Energy on Hold” ATP is formed by the direct transfer of a phosphate group from a high-energy substrate (Glycolysis) in an exergonic catabolic pathway to ADP Powering the Electrochemical gradient

CR Available O 2 Purpose: Regenerates NAD+ for glycolysis

* Muscle Cells * Bacteria sugar in milk to Lactic acid (*Flavors, yogurt) *enzyme?

* Ethanol is the “waste product”

1. Remove a carboxyl group COOH (Decarboxylation, as CO 2 and H ) 2. Oxidize the 2C fragment, 2NAD+ is reduced to 2NADH ETC 3. Coenzyme A ‘transport molecule’ is attached to the acetyl group The S-C bond can be broken, Acetyl group (2C X 2) enters Krebs) Formation of Acetyl CoA from Pyruvate (3C) “The Escort” Intermembranal Area of the Mitochondria STEPS:

* TOTAL ENERGY SO FAR: 4 NADH (2 Glycolysis, 2 formation of acetyl CoA) 2 ATP (From Glycolysis)

* CITRIC ACID CYCLE (TRICARBOXYLIC-TCA) * Mitochondrial Matrix * 5 steps * TWO Cycles/Glucose * YIELD: (per Glucose) 4 CO 2 2 ATP 6 NADH 2 FADH 2

1. 4C + 2C = 6C Oxaloacetic + Acetyl = Citric Acid 2. 2 CO 2 removed/cycle (4/glucose) Decarboxylation 3. Substrate level Phosphorylation, 2 ATP/Glucose 4. OA4C > 6C > 5C > 4C > 4C > OA4C Per Glucose: 4 CO 2, 2 ATP 6 NADH, 2 FADH 2 “Energy On Hold” STEPS/YIELD KREBS

Protons (H + ) move across I, III and IV (Each electron moves 1 H out). One NADH…2 e- From I to IV…6 H + out of matrix (At V- can get 1 ATP/2 H+) (Inner membrane NOT permeable to NADH; glycolysis count is different) One FADH 2 …2e- from II to IV…4 H + out of matrix……eventually 2 ATP Electrons fall to successively lower energy levels as carriers are reduced/ oxidized…moving H + and resulting in the oxidative phosphorylation of ATP Protons re-enter the matrix at V with ATP synthase enzyme; chemiosmosis Final electron acceptor is Oxygen, + 2P, produces H 2 O (No O 2, No ETC)

*NADH From Glycolysis *NADH from Glycolysis: In Liver, Kidney, Heart- 3ATP; Skeletal muscle, brain- 2 ATP 1 mol glucose burned- 686kcal released as heat ATP G is ~274kcal 274/686 40% efficient