1. CHAPTER 9 CELLULAR RESPIRATION
1. _____________________ and ________________ are catabolic, energy-yielding pathways
Catabolic processes
Enzyme
Complex molecule
(High energy)
Simpler molecule
(Low energy)
+ heat + energy
2 common types
1. ________________- to be discussed later
Organic compounds CO2 + H2O + Energy
2. ____________________-
Organic compounds + O CO2 + H2O + Energy
This process uses _________.
Note:
This occurs in the _______________

2. An example of cellular respiration- _____________ of glucose
C6H12O6 + 6O CO2 + 6H2O + Energy (ATP + heat)
Glucose
An ________________reaction
D G = kcal per mole of glucose.
Drives the generation of ATP from ADP
ATP then ____________________ other molecules, allowing them to do work

3. 2. _______ reactions release ___________ when electrons move closer to _____________ atoms
_______ (reduction-oxidation) reactions- transfer of electrons from one reactant to another or changes bond type (single to double).
The loss of electrons is called _____________.
The addition of electrons is called _____________.
Example:
NaCl Na+ + Cl-
sodium is ____________and chlorine is ____________
Na is the ____________________ and reduces Cl.
Cl is the _____________________ and oxidizes Na.

4. 3. Electrons “fall” from organic molecules to ________ during cellular respiration
In the summary equation of cellular respiration: C6H12O6 + 6O CO2 + 6H2O
Glucose is ___________, oxygen is ____________, and electrons loose potential energy.
At key steps, hydrogen atoms are stripped from glucose and passed first to a coenzyme, like NAD+ (nicotinamide adenine dinucleotide).
Dehydrogenase enzymes strip two hydrogen atoms from the fuel (e.g., glucose), pass _______________ ________to NAD+ (to make NADH) and release H+.
H-C-OH + NAD+ -> C=O + NADH + H+

5. NAD + functions as the __________________ in many of the redox steps during the catabolism of glucose.
Energy is tapped to synthesize ATP as electrons “fall” from __________ to oxygen.
Fig. 9.4

6. The________ ___________
_______ breaks the fall of electrons to __ into several steps.
Fig. 9.5
________ shuttles electrons to the “top” of the chain.
At the “bottom”, oxygen captures the ___________ and ___ to form water.
The free energy change from “top” to “bottom” is ___ kcal/mole of NADH.
Energy used to make ATP!

7. (in mitochondrial matrix)
1. Respiration involves glycolysis, the Krebs cycle, and electron transport
2. ______________
(in mitochondrial matrix)
3. ___________ ____________
(In inner mitochondrial membrane)
1. __________
(In cytoplasm)
Fig. 9.6
End result: ATP is generated

8. 2 ADP
2 ATP
2 ADP
2 ATP
__________
______
Glucose
2 Pyruvate
6 CO2
8 NADH
2 NAD+
_________
8 NAD+
2 FAD+
2 FADH2
_____
6 ADP
28 ADP
_________
Add up total ATP generated : =___

9. In the electron transport chain-
the _________ move from molecule to molecule until they combine with oxygen and hydrogen ions to form __________.
As they are passed along the chain, the energy carried by these electrons is stored in the mitochondrion in a form that can be used to synthesize ATP via _____________________________________.
Oxidative phosphorylation produces almost ____ of the ATP generated by respiration.

10. These are generated by ______________________________
2 ADP
2 ATP
2 ADP
2 ATP
Glucose
2 Pyruvate
6 CO2
What is substrate level phosphorylation?
Enzyme
An _______ transfers a phosphate group from an organic molecule (the substrate) to ____, forming ____.

11. 2. Glycolysis
Glucose, a six-carbon sugar, is split into two, 3-carbon sugars then into ________.
Each of ___ steps in glycolysis is catalyzed by a specific _________.
Divided into two phases:
an _______________ __________
2 ATP used
an _____________ _________.
4 ATP + 2 NADH produced
Net = 2 ATP + 2 NADH

12. 1st Phosphate group added 2nd Phosphate group added
Glycolysis
Energy investment phase
1st Phosphate group
added
2nd Phosphate group
added
Two 3-carbon molecules, each with one phosphate
Fig. 9.9a

13. Energy payoff phase
2 PO4
1 PO4
0 PO4
Fig. 9.9b

14. 3. The Krebs cycle completes the energy-yielding __________ of organic molecules
2 ADP
2 ATP
2 ADP
2 ATP
Glycolysis
Krebs
Glucose
2 Pyruvate
6 CO2
If ___________ is present, pyruvate enters the _________________ where enzymes of the Krebs cycle complete the ______________ of the organic fuel to carbon dioxide.

15. What happens to pyruvate?
Answer- Pyruvate is modified to ____________ which enters the Krebs cycle in the matrix.
1. A _______________ group is removed as CO2.
2. A pair of ______________ is transferred from the remaining two-carbon fragment to NAD+ to form NADH.
3. The oxidized fragment, acetate, combines with coenzyme A to form ___________
Fig. 9.10

16. The Krebs cycle consists of ____ steps.
Named after Hans Kreb – 1930s
Each cycle produces
one ATP by _____________ _____________
three ________
and one ______
Fig. 9.12

17. The conversion of pyruvate and the Krebs cycle produces large quantities of _______________.
2 carbon atoms enter
2 carbon atoms released as CO2
Note the Krebs cycle is never depleted of ________: 2 in, 2 out
Fig. 9.11

18. 4. The inner mitochondrial membrane couples _____________ to ATP synthesis
Only __ of __ ATP produced by respiration of glucose are derived from ________________ ________________________.
The vast majority of the ATP comes from the energy in the ________ carried by ______ (and ________).
Thousands of copies of the electron transport chain are found in the _________ (the inner membrane of the mitochondrion).
Electrons drop in _____________ as they pass down the electron transport chain.

19. Electrons carried by __________ are transferred to the first molecule in the electron transport chain, _____________________.
The electrons continue along the chain which includes several ____________ proteins and one lipid carrier.
The electrons carried by _____ have lower free energy and are added to a later point in the chain.
Electrons
Electrons from NADH or FADH2 ultimately pass to oxygen.
The electron transport chain generates no ATP directly.
Note:
Fig. 9.13

20. Then where does the ATP come from??
A protein complex, ___ _______, in the cristae actually makes ATP from ADP and Pi.
ATP uses the energy of a _____________ (from the electron transport chain) to power ATP synthesis.
This __________________ develops between the intermembrane space and the ________.
Termed _______________ ______________________
Fig. 9.14

21. In plants- light supplies the ____________
This coupling of the redox reactions of the electron transport chain to ______________ is called _____________________.
Fig. 9.15
In plants- light supplies the ____________
In bacteria, the H+ gradient is across the plasma membrane

22. 5. Cellular respiration generates many ___ molecules for each _____ molecule it _________: a review
Most energy is from __________________________
glucose NADH ET chain proton-motive force ATP
A one six-carbon glucose molecule is oxidized to six CO2 molecules.
Some ATP is produced by substrate-level phosphorylation

23. Maximum yield is 38 ATP
Fig. 9.16

24. How efficient is respiration in generating ATP?
Complete oxidation of glucose = _______ kcal/mole.
Formation of each ATP requires = _____ kcal/mole.
Efficiency of respiration is
____ kcal/mole x ___ ATP/glucose = ___%.
686 kcal/mole glucose
The other approximately 60% is lost as ______.
Cellular respiration is remarkably efficient in energy conversion.

25. 6. _____________ enables some cells to produce ATP without the use of _______
Oxidation refers to the loss of _______to any electron acceptor, not just to oxygen.
In glycolysis, NAD+ is the ________ agent, not O2.
Glycolysis generates _____ whether oxygen is present (aerobic) or not (anaerobic).
Fig. 9.17a
Problem- Fermentation (anaerobic catabolism) still requires NAD+ to accept electrons.
Solution-In _______________, NAD+ comes from the conversion of pyruvate to _________

26. A second solution to the NAD+ problem:
__________________________
( pyruvate is reduced directly by NADH to form ___________)
Muscle cells switch from _________respiration to lactic acid ___________ to generate ATP when __ is scarce.
The waste product, lactate causes muscle fatigue but ultimately it is converted back to pyruvate in the liver.
Fig. 9.17b

27. Compare respiration and fermentation
Similarities
Both use glycolysis to generate _______
Both use NAD+ as an _________________.
Respiration
Fermentation
Type
Aerobic
Anaerobic
NAD+ regeneration
___
Organic molecules
Energy yield
___ ATP
__ ATP

28. At a cellular level, human _________ cells can behave as facultative anaerobes, but ________ cells cannot.
For facultative _________, pyruvate is a fork in the metabolic road that leads to two alternative routes.
Fig. 9.18

29. 7. How do other ________________ fit into glycolysis and the Kreb cycle??
Answer- ____________ _____________ can all enter the pathway
________ are degraded to amino acids, then deaminated (nitrogen secreted as urea, ammonia)
______________are broken down to glucose.
______must be digested to glycerol and fatty acids.

30. Intermediaries in glycolysis and the Krebs cycle can be diverted to _____________ pathways.
Examples:
a human cell can synthesize about ______ the 20 different amino acids by modifying compounds from the _____________.
___________ can be synthesized from pyruvate and fatty acids from acetyl CoA.
Excess carbohydrates and proteins can be converted to _______ through intermediaries of glycolysis and the Krebs cycle.

31. 8. _____________________ control cellular respiration
Basic principles of ____________________ regulate the metabolic economy.
If a cell has an excess of a certain amino acid, it typically uses feedback inhibition to prevent the diversion of more intermediary molecules from the Krebs cycle to the synthesis pathway of that amino acid.
The rate of catabolism is also regulated, typically by the level of _________ in the cell.
If ATP levels drop, catabolism speeds up to produce more ATP.

32. Control of catabolism is based mainly on regulating the activity of __________ at strategic points in the catabolic pathway.
One strategic point occurs in the third step of glycolysis, catalyzed by ______________________
When ATP levels are high, inhibition of this enzyme slows ________________.
_____________, the first product of the Krebs cycle, is also an inhibitor of phosphofructokinase.
Fig. 9.20