Mader: Biology 8th Ed.

Cellular Respiration

Chapter 8

1

Mader: Biology 8th Ed.

Outline

• Glycolysis

• Transition Reaction

• Citric Acid Cycle

• Electron Transport System

• Fermentation

• Metabolic Pool

– Catabolism

– Anabolism

2

Mader: Biology 8th Ed.

Cellular Respiration

• A cellular process that requires oxygen and gives off carbon dioxide.– Most often involves complete breakdown

of glucose to carbon dioxide and water.!Energy within a glucose molecule is

released slowly so that ATP can be produced gradually.

!NAD+ and FAD are oxidation-reduction enzymes active during cellular respiration.

3

TA p132

4

Fig. 8.1

5

Mader: Biology 8th Ed.

Glucose Breakdown

• During glycolysis, glucose is broken down in cytoplasm to two molecules of pyruvate.

• During transition reaction, pyruvate is oxidized, NADH is formed, and waste carbon dioxide is removed.

• Citric acid cycle results in NADH and FADH2, release of carbon dioxide, and

production of additional ATP.• Electron transport chain produces 32 or 34

molecules of ATP.

6

Mader: Biology 8th Ed.

Glucose Breakdown

7

Mader: Biology 8th Ed.

Glycolysis

• Two ATP are used to activate glucose that splits into PGAL.

• Oxidation of PGAL and subsequent substrates results in four high-energy phosphate groups, which synthesize four ATP.

– Substrate-Level Phosphorylation

8

Mader: Biology 8th Ed.

Glycolysis

9

Mader: Biology 8th Ed.

Inside the Mitochondria

• End product of glycolysis, pyruvate, enters the mitochondria, where it is oxidized to carbon dioxide during the transition reaction and citric acid cycle.

– CO2 and ATP are transported out of

mitochondria into the cytoplasm.

10

Fig. 8.3

11

Fig. 8.4

12

Mader: Biology 8th Ed.

Mitochondrion Structure and Function

13

Mader: Biology 8th Ed.

Transition Reaction

• Connects glycolysis to the citric acid cycle.

14

Fig. 8.6

15

Mader: Biology 8th Ed.

Citric Acid Cycle

• Originally called Krebs cycle.

16

Mader: Biology 8th Ed.

Electron Transport System

• As electrons pass down the electron transport system, energy is captured and ATP is produced.

– Oxidative phosphorylation refers to the production of ATP as a result of energy released by the electron transport system.

17

Fig. 8.8

18

Mader: Biology 8th Ed.

19

Mader: Biology 8th Ed.

Fermentation

• Glycolysis followed by reduction of pyruvate by NADH to either lactate or alcohol and carbon dioxide.

– Anaerobic pathway.

– Can provide rapid burst of ATP.

!Common in muscle cells.

20

Fig. 8.10

21

Mader: Biology 8th Ed.

Fermentation

22

Mader: Biology 8th Ed.

Metabolic Pool

• Carbohydrates, fats, and proteins can be used as energy sources.

– Catabolism produces molecules that can also be used for anabolism and other compounds.

!All reactions in cellular respiration are part of a metabolic pool, and their substrates can be used for catabolism or anabolism.

23

Fig. 8.11

24

Mader: Biology 8th Ed.

Review

• Glycolysis

• Transition Reaction

• Citric Acid Cycle

• Electron Transport System

• Fermentation

• Metabolic Pool

– Catabolism

– Anabolism

25

Mader: Biology 8th Ed.

26