1. The Krebs Cycle and Electron Transport
Chapter 9.2
The Krebs Cycle and Electron Transport

2. Oxygen is such an important part of cell respiration because it is one of the most powerful electron acceptors.
The last 2 steps of cell respiration require energy and therefore are called aerobic.

3. During the Krebs cycle, pyruvic acid is broken down into carbon dioxide (what you breathe out) and energy.
The Krebs Cycle takes place in the mitochondria. One of the carbon atoms from pyruvic acid breaks off to become carbon dioxide. The other 2 carbons become a compound called acetyl-CoA.
This will join with another molecule to form citric acid.
The Krebs Cycle

4. As the Krebs Cycle continues citric acid is broken down and more carbon dioxide is release and electrons are transferred to electron carriers.
For each turn of the cycle4 NADH are formed, 1 FADH2 (another electron carrier) is formed, and 1 ATP is formed.

5. What happens to the things produced in the Krebs Cycle: Carbon dioxide is released, ATP is used for cell activities, NADH and FADH2 are moved to the electron transport chain.

6. The electron transport chain takes electrons and uses their energy to make ADP to ATP.
The electrons are taken from NADH and FADH2 and moved through the electron transport chain. The electrons move from one protein to another moving toward oxygen. At the end the electrons (as hydrogen) combine with oxygen to form water.
Electron Transport

7. As the electrons move through the membrane their energy moves hydrogen's across the mitochondrial membrane. This creates a gradient where we have more positive hydrogen's on one side of the membrane than on the other.

8. This hydrogen gradient will make hydrogen's want to move back across the membrane and they have to go through ATP synthase to do that. ATP synthase is powered by the hydrogen to attach a phosphate onto ADP to make ATP.

9. The Krebs cycle and electron transport chain makes about 36 ATP for 1 glucose molecule.
All foods that we eat can be broken down into simple substances that can run through the Krebs cycle.
The Totals