1. 9.2 The Process of Cellular Respiration
Lesson Overview
9.2 The Process of Cellular Respiration

2. THINK ABOUT IT
Food burns! How does a living cell extract the energy stored in food without setting a fire or blowing things up?

3. Glycolysis _________ is the first stage of cellular respiration.
During glycolysis, glucose is broken down into 2 molecules of the 3-carbon molecule ____________. Pyruvic acid is a reactant in the ___________.
___ and _____ are produced as part of the process.

4. ATP Production
The cell “________” 2 ____ molecules into its “_________” to get glycolysis going.

5. ATP Production
___________ then produces _______ __________, giving the cell a net gain of _____ molecules for ______ molecule of _______ that enters glycolysis.

6. NADH Production
During glycolysis, the electron carrier ______ (nicotinamide adenine dinucleotide) accepts a pair of high-energy electrons and becomes _________.

7. NADH Production
_____ carries the high-energy electrons to the _________________________, where they can be used to produce more _____.
______ molecules are produced for every molecule of ________ that enters glycolysis.

8. The Advantages of Glycolysis
Glycolysis produces ATP ___________, which is an advantage when the ________________ of the cell suddenly increase.
Glycolysis ____________ require _______, so it can quickly supply energy to cells when oxygen is unavailable.

9. The Krebs Cycle
During the _________, the second stage of cellular respiration, pyruvic acid produced in glycolysis is broken down into carbon dioxide in a series of _________________ reactions.
The Krebs cycle is also known as the _____________ because citric acid is the ___________________ in this series of reactions.

10. Citric Acid Production
Pyruvic acid from glycolysis enters the _____, the innermost compartment of the mitochondrion.

11. Citric Acid Production
Once pyruvic acid is in the mitochondrial matrix, ______ accepts ______ ______________ to form _____. One molecule of _____ is also produced.
The remaining 2 carbon atoms react to form ___________.

12. Citric Acid Production
Acetyl-CoA combines with a 4-carbon molecule to produce _____ ______.

13. Energy Extraction
Citric acid is broken down into a _________ __________ and then a __________________. Two molecules of CO2 are released. The _________________ can then start the cycle again by combining with acetyl-CoA.

14. Energy Extraction
Energy released by the breaking and rearranging of carbon bonds is captured in the forms of _____, ______, and _______.

15. Energy Extraction
For each turn of the cycle, one ____ molecule is converted into ______. ATP can directly power the cell’s activities.

16. Energy Extraction
The electron carriers NAD+ and FAD each accept pairs of high-energy __________ to form NADH and FADH2. NADH and FADH2 are ______ in the _______ ______________ to ______________.

17. Energy Extraction
Remember! Each molecule of glucose results in 2 molecules of pyruvic acid, which enter the Krebs cycle. So each molecule of glucose results in ______ complete “_____” of the __________.
Therefore, for each glucose molecule, _______ molecules, ____ molecules, _______ molecules, and ___ __________ molecules are produced.

18. Electron Transport
NADH and FADH2 pass their high-energy electrons to ______________________ in the electron transport chain.

19. Electron Transport
At the end of the electron transport chain, the _________ combine with __ ions and ______ to form water.

20. Electron Transport
Energy generated by the electron transport chain is used to move H+ ions against a ________________ _________ across the inner mitochondrial membrane and into the ____________________.

21. ATP Production
H+ ions pass back across the _________________________ through the ____________, causing the ATP synthase molecule to spin. With each rotation, the ATP synthase attaches a _____________ to _____ to produce ____.

22. Energy Totals
In the presence of oxygen, the complete breakdown of glucose through cellular respiration results in the production of ________ molecules.
This represents about 36 percent of the total energy of glucose. The remaining ____ _______________________.

23. Energy Totals
The cell can generate ATP from just about any source, even though we’ve modeled it using only glucose. Complex carbohydrates are broken down into simple sugars like glucose. Lipids and proteins can be broken down into molecules that enter the Krebs cycle or glycolysis at one of several places.