D. KREBS CYCLE

2. occurs in the matrix of the mitochondria

3. only occurs if oxygen is present

1. Krebs cycle allows the cell to get more energy out of the acetyl-CoA product of the oxidation of pyruvate

remember the cell is trying to

release NAD+ to allow glycolysis to continue

produce ATP

COOHO=C CH2

COOH

COOH CH2

HOC – COOH CH2

COOH

acetyl-CoA

CH3

C=O S-CoA

4. Details

H2O

CoA-SH

hydrase

oxaloacetate

citrate

COOH CH2

HOC – COOH CH2

COOH

COOH CH2

HC – COOH HOCH COOH

isomerase

citrate

isocitrate

COOH CH2

HC – COOH HOCH COOH

COOH CH2

CH2 C=0 COOH

NAD+

NADH + H+

CO2

dehydrogenase

decarboxylase

isocitrate

alpha-ketoglutarate

COOH CH2

CH2 C=0 COOH

COOHCH2

CH2

C=OS – CoA

NAD+

NADH + H+

CO2

CoASH

dehydrogenase

decarboxylase

alpha-ketoglutarate

succinyl-CoA

COOHCH2

CH2

C=OS – CoA

COOHCH2

CH2

COOH

CoASH

GTP

GDP + Pi

ADP

ATP

phosphorylase

H2O

hydrase

succinyl-CoA

succinate

COOHCH2

CH2

COOH

COOH CH llHC COOH

FAD+

H2

dehydrogenase

FAD

succinate

fumarate

COOH CH llHC COOH

COOHHOCH CH2

COOH

H2O

hydrase

fumarate

malate

COOHHOCH CH2

COOH

COOHO=C CH2

COOH

NAD+

NADH + H+

dehydrogenase

malate

oxaloacetate

START AGAIN

COOHO=C CH2

COOH

COOH CH2

HOC – COOH CH2

COOH

acetyl-CoA

CH3

C=O S-CoA

Oxaloacetate

citric acid

so this is sometimes called the citric acid cycle

5. EQUATION:

acetyl-CoA + 3 NAD+ + FAD+ + H20 + ADP + Pi

2 CO2 + 3 [NADH + H+] + FADH2 + ATPCoASH +

E. SUMMARY – so far for HIGH ENERGY PRODUCTS

where

glucose glycolysis

cytoplasm

2 ATP

oxidation of pyruvate

oxidation of pyruvate

matrix of mitochondria

2 [NADH + H+]

4 ATP

oxidation of pyruvate

oxidation of pyruvate Kreb’s cycle

Kreb’s cycle

2 [NADH + H+] 2 ATP6 [NADH + H+]

2 FADH2

matrix of mitochondria

where

remember the cell is trying to

release NAD+ to allow glycolysis to continue

produce ATP

Krebs made no NAD+, it used 6

Krebs made only 2 more ATP