Cell Respiration – An Overview
4 Pathways:
1
Glycolysis
2
Link Reaction AKA Pyruvate Oxidation AKA Acetyl CoA Formation
3
Krebs Cycle AKA Citric Acid cycle
4
Oxidative Phosphorylation (Electron Transport Chain + Chemiosmosis)
1. C6H12O6 and 6 O2
2. 6 CO2, 6 H2O, and energy (ATP)
3.
a. glycolysis
b. link reaction, Krebs cycle, and oxidative phosphorylation
c. oxidative phosphorylation
d. link reaction and Krebs cycle
e. oxidative phosphorylation (specifically - the electron transport chain)
4.
a. glycolysis (2 net ATP), Krebs (2 ATP), oxidative phosphorylation (~34 ATP)
b. In this model, 38 ATP are formed (but will be talked about later that the actual number can vary)
c. ADP and Pi (inorganic phosphate)
d. active transport, muscle contraction, protein synthesis, cell signaling (response)…
5. NADH & FADH2
6.
a. zero
b. H+ would probably be most attracted to O2 because oxygen is the most electronegative of the 3
molecules
c. No, in order for a neutral particle to be made, a positive particle must combine with a negative
particle
7.
a. -1
b/c.
2e- + NAD+ + H+  NADH
2e- + FAD + 2H+  FADH2
2e- + ½ O2 + 2H+  H2O
8. Reduction (all molecules are gaining elections [gaining H])
9. NADH is the reduced form because it gained elections from NAD+
10. Glucose is being oxidized because it is being broken down (loses electrons/H at each step)
11. CO2 would be the most oxidized form of the molecules in #10. It has the least carbons. All the C-H bonds
have been broken and C=O bonds were formed in CO2
12. NAD+ and H+
13.
a. NAD+ and FAD
b. Oxidation because electrons are being lost
c. They will go back to be reused in the earlier steps of respiration (they are “recycled”)
14.
a. 2ATP would be made if there is no oxygen available for oxidative phosphorylation.
b. The supply of NAD+ would decrease because they would all be “stuck” in the reduced form of
NADH. NADH would have nowhere to “drop off” their electrons because oxygen is needed to be the final
electron receptor in oxidative phosphorylation. (Fermentation would occur in these instances – fermentation is
a way for NADH to be oxidized back to NAD+ so that glycolysis could continue.)
Glycolysis and the Krebs Cycle
1.
a. glucose
b. 6
2.
a. 3
b. 2
3. Yes, glycolysis requires an initial input of 2 ATP. When converting glucose  2 PGAL, each PGAL has a
phosphate group which came from the 2 ATP.
4. PGAL is has the highest potential energy because it has the most free (available) energy compared to the
other molecules. From PGAL, 2 NADH and 4 ATP are made; whereas from 1, 3-BPG, only 4 ATP are made.
5. Less because according to Model 1, it is lower on the diagram than glucose. It has lower potential energy
because it contains less bonds that store energy (6C vs. 3C)
6. 2 ATP
7. NAD+ is an electron acceptor (NADH is an electron carrier)
8. The 4 Pi that are needed to make ATP come from the 1,3-BPG molecule. There are 2 1,3-BPG molecules,
each one has 2 phosphate groups.
9. mitochondria
10.
a. No because it is polar (carboxyl and carbonyl groups)
b. Would need some kind of transport protein/protein channel
11. carboxyl group is removed (--COO-)
12.
a. acetyl
b. 2
c. Acetyl CoA
d. IDK lol. I don’t see how Model 2 shows it…but in the textbook it is shown with a “ ~ ” looking
bond.
13. no
14. yes, NADH
15. 2 acetyl CoA, 2 CO2, 2 NADH
16. mitochondrial matrix
17. acetyl group (of acetyl CoA)
18. no
19.
a. 4
b. 6
c. from acetyl group
20.
a. 5
b. CO2
21.
a. 4
b. CO2
22. 3 NADH, 1 FADH2, 1 ATP
23. Citrate because it has the most carbons (the most bonds that store energy). Oxidation of citrate results in all
the high energy products in #22.
24. Oxaloacetate because it has the least C-H bonds available for oxidation
25. Has low potential energy on its own (because has the fewest bonds) but when combined with oxaloacetate,
they form the molecule with the highest potential energy (citrate).
26. 2
27. Each glucose molecule produces 4 CO2, 2 ATP, 6 NADH, and 2 FADH2 in the Krebs cycle.
28. no