The Krebs Cycle

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Slide 1

The Krebs Cycle

Occurs in the matrix of the mitochondrion

Aerobic phase (requires oxygen)

2-carbon acetyl CoA joins with a 4-carbon compound to form a 6- carbon compound called Citric acid

Slide 2

Citric acid (6C) is gradually converted back to the 4-carbon compound

-ready to start the cycle once more

The carbons removed are released as CO2

-enzymes controlling this process called decarboxylases

The hydrogens, which are removed, join with NAD to form NADH2

-enzymes controlling the release of hydrogen are called dehydrogenases

Slide 3

Slide 4

The Cytochrome System

6 points along pathway where hydrogen is released and temporarily bound to NAD

Reduced coenzyme NADH2 transfers hydrogen to a chain of hydrogen carriers called cytochrome system

These systems are attached to the cristate of every mitochondrion

Slide 5

Transfer of hydrogen from each NADH2 along system

-produces 3 ATP

-process called oxidative phosphorylation

Complete oxidation of glucose yields 38 ATP

-2 during glycolysis

-36 during oxidative phosphorylation

Slide 6

Slide 7

The role of oxygen

Final hydrogen acceptor

Combines to form water

Controlled by enzyme cytochrome oxidase

Presence of oxygen also essential for hydrogen to pass along the cytochrome system