CELLULAR RESPIRATION

How Cells Release Energy

Aerobic Cellular Respiration

1. Glycolysis

4. Electron Transport System

3. Krebs Cycle

Anaerobic Cellular Respiration

1. Glycolysis

2. Fermentation

Cellular Respiration

Anaerobic Cellular Respiration

2. Fermentation

1. Glycolysis

1. Glycolysis(Sugar Splitting)

C6H12O6

Glucose

2 NAD+ 2 NADH

2 ATP2 ADP

Takes place in the cytoplasm of all cells

Pyruvate Pyruvate

2. Fermentation

Alcoholic Fermentation

Pyruvate

Alcohol CO2

2 NADH 2 NAD+

The Significance of fermentation is to regenerate NAD+ from NADH for its continuous role in glycolysis

+

2. Fermentation

Lactic Acid Fermentation

Pyruvate

2 NADH 2 NAD+

The Significance of fermentation is to regenerate NAD+ from NADH for its continuous role in glycolysis

Lactic acid

Fermentation does NOT produce additional ATP

The Significance of fermentation is to regenerate NAD+ from NADH for its continuous role in glycolysis

During anaerobic cellular respiration only 2 ATP are produced from one initial glucose molecule

Aerobic Cellular Respiration

1. Glycolysis

4. Electron Transport System

3. Krebs Cycle3. Krebs Cycle: Step a

3. Krebs Cycle: Step b

1. Glycolysis(Sugar Splitting)

C6H12O6

Glucose

2 NAD+ 2 NADH

2 ATP2 ADP

Takes place in the cytoplasm of all cells

Pyruvate Pyruvate

The output of Glycolysis is:

2 ATP2 NADH

The 2 pyruvates produced by glycolysis in thecytoplasm are transported into the mitochondrion tocontinue aerobic cellular respiration in Krebs cycle

1st pyruvate

1 CO2

Acetyl group

+CoACoA

Acetyl-CoA

3. Krebs Cycle Takes place in the mitochondrion

Step a

1 NADH

2nd pyruvate

1 CO2

Acetyl group

+CoACoA

Acetyl-CoA

3. Krebs Cycle Takes place in the mitochondrion

Step a

1 NADH

The output of Krebs Cycle step a is:

2 CO22 NADH

3. Krebs Cycle

Step b 1st Acetyl-CoA

CoA

+

4-C- compound

6-C-Compound

2 CO2

1 ATP

3 NADH

1 FADH2

3. Krebs Cycle

Step b 2nd Acetyl-CoA

CoA

+

4-C- compound

6-C-Compound

2 CO2

1 ATP

3 NADH

1 FADH2

The output of Krebs Cycle step b is:

2 ATP4 CO2

6 NADH2 FADH2

The output of Krebs Cycle

both steps is:2 ATP6 CO2

8 NADH2 FADH2

The output of Krebs Cycle

step b is:2 ATP4 CO2

6 NADH2 FADH2

The output of Krebs Cycle

step a is:2 CO2

2 NADH

Summary of energy harvest

• GLYCOLYSIS• 2 ATP • 2 NADH

• Krebs Cycle:• 2 ATP• 6 CO2• 8 NADH• 2 FADH2

• 4 ATP can be used for cellular work

• 6 CO2 are released• Raw materials for

electron transport system:

• 10 NADH• 2 FADH2

An Overview of the Electron Transport System

The Electron Transport System

 

1. NADH and FADH2 pass electrons to the first protein in the electron transport system (ETS).

 2. Electrons pass from energy carrier to the next.

 3. With each transfer, energy is released

4. This energy is used to pump hydrogen ions into the outer compartment of the mitochondrion.

5. Hydrogen ions build up in the outer compartment (higher concentration of H+ in the outer compartment than in the matrix).

6. Hydrogen ions flow back across the membrane through an enzyme (ATP synthase) that synthesizes ATP

7. The last protein in the ETS finally passes electrons to oxygen along with hydrogen ions, generating water.

The Electron Transport System

Electron Transport System

Most of ATP is produced during ETS

ETS produces 32 ATP

The Overall Equation of CR

C6H12O6 + 6 O2

6 CO2 + 6 H2O + 36 ATP + Heat