ETC and metabolic poisons

Question 1

What are the 3 enzymes of the electron transport chain?

Answer 1

1. NADH dehydrogenase complex
2. Cytochrome b-c1 complex
3. Cytochrome oxidase complex

Question 2

What are the 2 carriers?

Answer 2

1. Co enzyme Q (ubiquinone)

2. Cytochrome C

Question 3

How are protons pumped across?

Answer 3

The transfer of electrons from one complex to another is energetically favourable and as they progress along the chain, the electrons lose energy. This energy is used to actively pump protons from the matrix to intermembrane space.

Question 4

What is respiratory control in the mitochondria?

Answer 4

Uptake of oxygen by mitochondria is controlled by the components of ATP production: Inorganic phosphate (Pi), and ADP.

More oxygen is consumed the less ADP present.

Question 5

What does cyanide and azide do?

Answer 5

Binds with high affinity to fe3= in cytochrome oxidase complex blocking final step of ETC

Question 6

Malonate?

Answer 6

Competitive inhibitor of succinate dehydrogenase. It slows down the flow of electrons from succinate to ubiquinone by inhibiting the oxidation of succinate to fumarate.

Question 7

Rotenone?

Answer 7

It inhibits the transfer of electrons from complex I to ubiquinone.

Question 8

Oligomycin?

Answer 8

Inhibits oxidative phosphorylation by binding to the ‘stalk’ of ATP synthase and blocking the flow of protons through the enzyme.

Question 9

DNP?

Answer 9

2,4-dinitrophenol. A proton ionophore which can shuttle protons across the inner mitochondrial membranes. This dissociates the reactions of ATP synthesis from the electron transport chain.