33. Electron Transport Chain

Question 1

What is the function of complexes 1, 2 and 4?

Answer 1

Proton pumps
As electrons move downhill they capture the released energy
Use it to pump H+ from matrix into intermembrane space
This forms an electrochemical gradient across inner mitochondrial membrane

Question 2

What is the process of chemiosmosis?

Answer 2

H+ can’t move through the hydrophobic core of plasma membrane
Can only move down its concentration gradient with channel proteins that form transmembrane hydrophilic tunnels
ATP synthase is the only one present in inner mitochondrial membrane
As ATP synthase carries H+ it catalyses the production of ATP

Question 3

Describe the electron transport chain

Answer 3

Complex 1 and 2 pass their electrons to ubiquinone (Q)
Q is reduced to QH2 and travels through membrane to deliver electrons to complex 3
As electrons move through complex 3, more H+ ions are pumped across the membrane
Electrons delivered to cytochrome C
Cyt C carries electrons to complex 4
Final batch of H+ pumped across membrane
Complex 4 passes electrons to O2
O2 accepts protons to form water

Question 4

What regulates the electron transport chain?

Answer 4

Need for ATP

Question 5

What can inhibit the ETC?

Answer 5

Riboflavin deficiency
Rotenone
Doxorubicin
Iron deficiency
Cn- and CO compete with O2 for binding