lec 14 slide 17

do all chlorophyll molcules go through charge separation step of photosynthesis

No — most use resonance energy transfer. Only the “special pair” chlorophyll undergoes charge separation leading to transfer of the electron

this “special pair” is in a special place called what

reaction center of the photosystem

How is the electron in the special pair chlorophyll excited?

By direct or indirect sunlight energy, which ionizes the electron and separates it from the chlorophyll.

What happens to the electron after it leaves the special pair?

It is transferred to a mobile electron carrier, usually a quinone, via intermediate electron carriers.

What charge does the special pair chlorophyll have after losing an electron?

Positive (+) — it becomes electron-deficient.

How does the special pair chlorophyll regain its neutral state?

By taking an electron from a donor, usually water, because chlorophyll is a strong oxidant

Why can chlorophyll extract electrons from water even though water is a weak donor?

Because the special pair chlorophyll is a strong electron acceptor (strong oxidant).

What happens to the electron on the quinone after charge separation?

It enters the electron transport chain (ETC) to pump protons across the thylakoid membrane.

How much energy is needed for charge separation in the special pair chlorophyll?

~100 photons/sec

How does the special pair chlorophyll manage charge separation if it can only absorb ~1 photon/sec?

Energy is accumulated from surrounding chlorophyll molecules via resonance energy transfer, funneling energy to the reaction center