Chemiosmosis

Question 1

What is the pathway of electrons derived from hydrogen atoms in the synthesis of ATP?

Answer 1

• Transferred from a donor molecule to a recipient.
• Sequence of reactions transfer electrons from one molecule to the next along a chain.
• Each transfer = redox reaction, one molecule is oxidised and the following is reduced.
• Oxidation reactions make energy available which is used to synthesise ATP.

Question 2

What is the pathway of protons derived from hydrogen atoms in the synthesis of ATP?

Answer 2

• Energy from oxidation pumps protons across a membrane so they’re more concentrated on one side
• Difference in concentration of protons and the charge on either side constitutes the electrochemical gradient and is a source of potential energy
• Protons flow down the gradient in chemiosmosis through ATP synthase and the energy released as it flows through is converted into chemical energy in ATP