• The homework due date has been postponed. It is now due on Thursday at 10:00 pm.

• The Chapter 7 Test will be on Friday

Chapter 7Glycolysis, Pyruvate Oxidation and

the Citric Acid Cycle

You Must Know

• The role of glycolysis in oxidizing glucose to two molecules of pyruvate.

• How pyruvate is moved from the cytosol into the mitochondria and introduced into the citric acid cycle.

• That the citric acid cycle oxidizes organic molecules to produce NADH and FADH2

Figure 7.6-1

Electronsvia NADH

Glycolysis

Glucose Pyruvate

CYTOSOL

ATP

Substrate-level

MITOCHONDRION

Substrate-level phosphorylation

Substrate

P

ADP

Product

ATP

Enzyme Enzyme

Figure 7.6-2

Electronsvia NADH

Glycolysis

Glucose Pyruvate

Pyruvateoxidation

Acetyl CoA

Citricacidcycle

Electronsvia NADH and

FADH2

CYTOSOL

ATP

Substrate-level

ATP

Substrate-level

MITOCHONDRION

Figure 7.6-3

Electronsvia NADH

Glycolysis

Glucose Pyruvate

Pyruvateoxidation

Acetyl CoA

Citricacidcycle

Electronsvia NADH and

FADH2

Oxidativephosphorylation:electron transport

andchemiosmosis

CYTOSOL

ATP

Substrate-level

ATP

Substrate-level

MITOCHONDRION

ATP

Oxidative

• For each molecule of glucose degraded to CO2 and water by respiration, the cell makes up to 32 molecules of ATP

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Glycolysis occurs in the cytoplasm

Glycolysis Pyruvateoxidation

Citricacidcycle

Oxidativephosphorylation

ATP ATP ATP

Glycolysis occurs whether or not O2 is present.

Energy Investment Phase

Energy Payoff Phase

Net

Glucose

Glucose

2 ADP 2 P

4 ADP 4 P

2 NAD 4 e− 4 H

2 NAD 4 e− 4 H

4 ATP formed − 2 ATP used

2 ATP

4 ATP

used

formed

2 NADH 2 H

2 Pyruvate 2 H2O

2 Pyruvate 2 H2O

2 NADH 2 H

2 ATP

Glycolysis

Figure 7.UN07

Glycolysis Pyruvateoxidation

Citricacidcycle

Oxidativephosphorylation

ATP ATP ATP

Figure 7.10

CYTOSOLPyruvate(from glycolysis,2 molecules per glucose)

CO2

CoANAD

NADH

MITOCHONDRION CoAAcetyl CoA H

In the presence of O2, pyruvate enters the mitochondrion (in eukaryotic cells).

Pyruvate is oxidized

Figure 7.10b

CoA

Citricacidcycle

FADH2

FAD

ADP Pi

ATP

NADH

3 NAD

3

3 H

2 CO2

CoAAcetyl CoACitric Acid Cycle

All along the citric acid cycle organic molecules are oxidized and NAD+ is reduced to become NADH and FAD is reduced to become FADH2.

The NADH and FADH2 produced by the cycle relay electrons extracted from food to the electron transport chain.