citric acid cycle

LECTURE: CELLULAR RESPIRATION STAGE 3 – CITRIC ACID CYCLE KIRSTIN BROWN

Lecture: CITRIC ACID CYCLE Outline: 1. Stage 3 o Review of stages 1 & 2 o The citric acid cycle o Summary

Overview Cellular Respiration o The step-by-step breakdown (oxidation) of

glucose (stages 1 – 3)

o Potential energy is transferred to ATP and

electron carriers (eg. NADH) o Electron carriers are used in stage 4 to make ATP STAGE 4 STAGE 1 STAGE 2

ATP NADH NADH

STAGE 3

ATP NADH FADH2

ATP

Overview Cellular Respiration o Stage 1: Glycolysis o Stage 2: Pyruvate processing o Stage 3: Citric acid cycle o Stage 4: Electron transport chain

STAGE 4 STAGE 1 STAGE 2

ATP NADH NADH

STAGE 3

ATP NADH FADH2

ATP

Overview Cellular Respiration o Stage 1: Glycolysis (cytosol) o Stage 2: Pyruvate processing (matrix) o Stage 3: Citric acid cycle (matrix) o Stage 4: Electron transport chain (inner

mitochondrial membrane)

glucose Cytosol

Inner membrane STAGE 1

Matrix STAGE 4 STAGE 3 STAGE 2

Mitochondria

Overview

1 glucose ATP

ATP

Investment phase Fructose-1-6-bisphosphate

STAGE 1

G3P

NAD+

DHAP

G3P

NAD+

NADH

NADH

ADP

ADP

ATP

ATP

Payoff phase ADP

ADP

ATP

ATP Pyruvate

Pyruvate

STAGE 2

NAD+

NAD+

NADH

NADH

Acetyl-CoA

Acetyl-CoA

STAGE 3

Total energy so far: +2 ATP, 4 NADH

Stage 3 The Citric Acid Cycle o Acetyl-CoA oxidized to CO2 ➢ 8 enzymatic steps ➢ Occurs in mitochondrial matrix Acetyl-CoA

CoA

Citrate

Oxaloacetate

NADH NAD+

NAD+ CO2

CO2 FADH2

NADH

NAD+ NADH

FAD GTP GDP

3x NADH, 1 FADH2, 1 GTP X 2 Total energy so far: +2 +4 ATP, 4 10NADH NADH, 2 FADH2

Stage 3 Summary glucose Cytosol

Inner membrane STAGE 1

Matrix STAGE 4 STAGE 3 STAGE 2

Mitochondria

Total energy so far: +4 ATP, 10 NADH, 2 FADH2

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Cellular Respiration: Stage 4