Instant Notes: Plant Biology

J1 – Photosynthetic pigments and the nature of light 137

CH 2

CH

N

N

N

N

Mg

CH 3 CH 3

A CH^2 CH^3 CH^3

CH 3

C

O

O

OCH 3

O CH C

CH 3

Hydrophobic tail

CH 2 (CH 2 CH 2 CH 2 ) 2

CH 3

CH 3

CH

CH 3

CH 2 CH 2 C CH 2 CH 2 CH 2 CH

O

Fig. 2. The structure of chlorophyll. Chlorophyll bdiffers from chlorophyll aby the substitution of a CHO group for the
CH 3 marked at position A.

Electron

donor A

Electron

acceptor Q

Antenna

Reaction

center

hv

hv

A

A+ Q–

e–

Q

Fig. 3. The reaction center. Chlorophyll and accessory pigments are grouped around a

central pair of reaction center chlorophylls. The absorbed energy is collected and conveyed to

the central pair of reaction center chlorophylls by resonance energy transfer (RET; arrows). The

energized electron from an electron donor, A, in the reaction center is then passed on to an

electron acceptor, Q. (Redrawn from Hopkins (1998) Introduction to Plant Physiology, 2nd

Edn, John Wiley & Sons.)