Light harvesting

Question 1

What is FRET?

Förster resonance energy transfer

Answer 1

The non-radioactive coupling of the transition of the donor pigment from its excited state to its ground state with the transition of the acceptor pigment from its ground state to its excited state.

-Excitation energy transfer, not the transfer of the electron itself
-Only happens when molecules are physically close to eachother so that their energy levels are overlapping

Question 2

How do antenna proteins use FRET?

Answer 2

To transfer energy across the light harvesting complex to the reaction centre
-excitation energy cascade downhill to reaction centre, where energy is trapped as electron transfer reaction

Question 3

What makes the special pair chlorophylls “special”?

Answer 3

Only redox active chlorophylls (can donate e-)
-Other chlorophylls can only transfer energy (via FRET) not e-