Glucose Metabolism 9.10

*Cellular Respiration

*3 Main Principles:

1.The point is to make ATP

2.Moving H-atoms…..moves energy from one molecule to another

3.Oxidation/ReductionOIL RIG *Coupled Reactions LEO GER

Oxidized? Reduced?

RESPIRATION: Process by which cells generate ATP through a series of redox reactions. Converting food energy* (C6H12O6) 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

*TWO MAIN TYPES:

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 Pi (Inorganic Phosphate)*Inorganic phosphate in

cytoplasm

Last 4 Steps: Kinase…Substrate Level Phosphorylation * ADP to ATP

5 steps

5 steps

*NADH*NAD+ + 2H

H = e- p+

H = e- p+

NAD+ + e- = NAD + H (e- and p+) = NADH

“Energy on Hold”

*Substrate Level Phosphorylation

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

CRAvailable O 2

Purpose: Regenerates NAD+ for glycolysis

*FERMENTATION

*Muscle Cells

*Bacteria

sugar in milk to

Lactic acid (*Flavors, yogurt)

*enzyme?

*FERMENTATION

*Ethanol

is the

“waste

product”

*Oxidative Decarboxylation

1. Remove a carboxyl group COOH (Decarboxylation, as CO2 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)

*Oxidative Decarboxylation

* CITRIC ACID CYCLE (TRICARBOXYLIC-TCA)

* Mitochondrial Matrix

* 5 steps

* TWO Cycles/Glucose

* YIELD: (per Glucose)

4 CO2

2 ATP

6 NADH

2 FADH2

1. 4C + 2C = 6C

Oxaloacetic

+ Acetyl = Citric Acid

2. 2 CO2 removed/cycle

(4/glucose) Decarboxylation

3. Substrate level Phosphorylation, 2 ATP/Glucose

4. OA4C > 6C > 5C

> 4C > 4C > OA4CPer Glucose: 4 CO2, 2 ATP

6 NADH, 2 FADH2

“Energy On Hold”

STEPS/YIELD

KREBS

*ELECTRON TRANSPORT CHAIN

• 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 FADH2…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 H2O (No O2, No ETC)

*NET ENERGY YIELD: Cellular Respiration

*NADH From Glycolysis

*NADH from Glycolysis: In Liver, Kidney, Heart- 3ATP; Skeletal muscle, brain- 2 ATP

1 mol glucose burned- 686kcal released as heat. 36-38 ATP G is ~274kcal 274/686 40% efficient