Lecture 17: Oxidative Phosphorylation

Question 1

• Know the flow of electrons during respiration

Answer 1

Electrons follow a downhill route:
Glucose
-
NADH
-
ETC
-
Oxygen

Question 2

• Describe the role of the electron transport chain in controlling the release of
energy during oxidative phosphorylation

Answer 2

ETC controls the release of energy for ATP synthesis.

Question 3

• Know the location of the electron transport chain and the multi-protein
complexes that make up the chain

Answer 3

• ETC is in the inner mitochondrial membrane.

Question 4

• Know how the free energy of electrons change as they move through the
electron transport chain and combine with the final electron acceptor, oxygen,
to form water

Answer 4

Electrons drop in free energy as they go down the chain and

are finally passed to O2, forming H2O

Question 5

• Know the complexes to which NADH and FADH2 donate their electrons and
describe the path these electrons take as they travel through the electron
transport chain

Answer 5

• Electrons enter the Chain via Complex I or II depending on whether they
enter as NADH or FADH2
• Electrons are passed from electron donors to acceptors until they reach the
final electron acceptor, oxygen
• When oxygen accepts the electron, it is reduced to water

Question 6

• Describe how oxidation and reduction relates to the movement of electrons
through the electron transport chain

Answer 6

• Coenzyme Q: accepts electrons from Complexes I and II and is reduced
to CoQH2
• CoQH2 diffuses in the inner membrane, docks, and transfers electrons to
Complex III
• Complex III transfers electrons to Cytochrome c
• Cytochrome c is reduced, diffuses in the membrane, and interacts with
Complex IV

Question 7

• Describe the role of protons in the electron transport chain including the
region where they accumulate within the mitochondria

Answer 7

• Energy is released as electrons are passed from NADH and FADH2 to O2
• Released energy
Ø Reduces electron carriers in the chain
Ø Pumps protons into the intermembrane space via Complexes I, III and IV
• End result:
Ø Accumulation of protons in the intermembrane space

Question 8

• Describe the relationship between proton concentrations within the
mitochondria and ATP Synthase

Answer 8

• Protons want to diffuse down their concentration gradient but cannot pass
through the membrane
• Proton concentration gradient contains high potential energy
• Protons in the intermembrane space diffuse down their electrical and
concentration gradients through ATP Synthase into the matrix

Question 9

• Know the basic structure of ATP Synthase

Answer 9

ATP Synthase:
F1 subunit (upper subunit):
- catalyzes synthesis of ATP
F0 subunit (lower subunit):
- forms a channel that rotates as protons pass through it.

Question 10

• Describe how the movement of protons through ATP Synthase generates
ATP

Answer 10

• Rotation of F0 leads to rotation of F1 in the
mitochondrial matrix

• Rotation of F1 causes conformational
changes in ATP Synthase that allow it to
catalyze the synthesis of ATP from ADP and P

Question 11

How much ATP is generated through ETC and oxidative phosphorylation.

Answer 11

32 molecules