Lecture 30: The electron transport chain

Question 1

Oxidative phosphorylation is the coupled process of:

Answer 1

• Electron transport through the ECT
  with the
• Phosphorylation of ADP to ATP by ATP synthase
  = processes are coupled by a proton gradient
• The ECT make the proton gradient
• ATP synthase uses the proton gradient

Question 2

What happens during the ETC?

Answer 2

• electrons are passed through a series of carriers
• electrons from NADH and FADH2 are fed into the lectern chain and are shuttled down to a oxygen which is the terminal electron acceptor
• they are oxidised; oxygen is reduced to water
• as electron moves down the ECT they lose energy resulting in protons being pumped across the membrane
• protons accumulate in the inter membrane space and create a PMF

Question 3

What are some example of inhibitors that inhibit the ECT?

Answer 3

Retone: inhibits the transfer of electrons from Complex 1 to Co-Q
Cyanide: binds to cytochrome a3 in complex 4

Question 4

How do inhibitors inhibit the ECT?

Answer 4

• Stops flow of electrons through the ETC
• Build up of reduced co-enzymes (NADH and FADH2)
• No proton gradient formed so no ATP produced
• Reactive oxygen species produced