5.2.6

Oxidative Phosphorylation

Test yourself

Oxidative Phosphorylation

Oxidative phosphorylation is the final stage in aerobic respiration.

Illustrative background for Inner mitochondrial membraneIllustrative background for Inner mitochondrial membrane ?? "content

Inner mitochondrial membrane

  • Oxidative phosphorylation takes place at the inner mitochondrial membrane.
  • There are several features of the membrane that allows production of ATP on a large scale:
    • Three electron carrier proteins (electron transport chain, ETC).
    • ATP synthase enzyme.
  • The space between the inner and outer mitochondrial membranes is called the intermembrane space.
Illustrative background for Electron transport chainIllustrative background for Electron transport chain ?? "content

Electron transport chain

  • NADH and FADH2 (from the Krebs cycle) are oxidised by the first electron carrier protein in the inner mitochondrial membrane.
  • This initiates oxidative phosphorylation because NADH and FADH2 release two protons and two electrons each.
  • The electrons are then transferred along the ETC.
Illustrative background for Proton gradientIllustrative background for Proton gradient ?? "content

Proton gradient

  • As the electrons move down the ETC, they lose energy.
  • This energy pumps the protons from NADH and FADH2 into the intermembrane space.
  • This creates a proton gradient (also known as an electrochemical gradient).
Illustrative background for ChemiosmosisIllustrative background for Chemiosmosis ?? "content

Chemiosmosis

  • The protons diffuse down the concentration gradient through the ATP synthase enzyme.
  • As protons flow through the ATP synthase, energy is released.
  • This energy converts ADP and inorganic phosphate to ATP.
  • This process is called chemiosmosis.
Illustrative background for The final electron acceptorIllustrative background for The final electron acceptor ?? "content

The final electron acceptor

  • After the electrons have reached the end of the ETC and protons have flowed through the ATP synthase enzyme, they combine with O2 to form water (H2O).
    • Oxygen is called the final electron acceptor for this reason.

Jump to other topics

1Biological Molecules

2Cells

3Substance Exchange

4Genetic Information & Variation

5Energy Transfers (A2 only)

6Responding to Change (A2 only)

7Genetics & Ecosystems (A2 only)

8The Control of Gene Expression (A2 only)

Go student ad image

Unlock your full potential with GoStudent tutoring

  • Affordable 1:1 tutoring from the comfort of your home

  • Tutors are matched to your specific learning needs

  • 30+ school subjects covered

Book a free trial lesson