OUTLINE 4A
Chapter 10 cont.
The Light Reactions: An Introduction - 10.3.1
>Photosystems
are the light-harvesting complexes of the thylakoid membranes.
Chlorophyll
a
and the accessory pigments are arranged into a
photosystem
(see fig. 10.12)
-satellite dish with receiver in the middle of the dish
Photosystems are composed of a few hundred pigment molecules
Components of a photosystem:
1.
Antenna complex
2.
Reaction-center chlorophyll
3.
Primary electron acceptor
There are two types of photosystems
1.
Photosystem I
(PS-I)
2.
Photosystem II
(PS-II)
Photosystem 1 - 10.3.2
Photosystem I =>
P700
Reaction center has a specialized chlorophyll that absorbs light best at 700 nm.
Photosystem 2 - 10.3.3
Photosystem II =>
P680
Reaction center has a specialized chlorophyll that absorbs light best at 680 nm
>>>>>The
light reactions
transform light energy to chemical energy (see fig 10.5)
---
Light reaction
- the reaction of photosynthesis that converts light energy to chemical bond energy in ATOP
and NADPH
-Solar energy to chemical energy
-Occurs in the thylakoid membranes
-Reduces
NADP
+
to NADPH
-H
2
O split, O
2
byproduct
-Generates ATP by
photophosphorylation
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NOTE: no sugar produced
---
photophosphorylation
the production of ATP that is coupled to the transfer of electrons energized by light
The Light Reactions: A Summary - 10.3.4
>Noncyclic electron flow
(see fig. 10.13)
The electrons that are excited from each of the photosystems can be donated to a primary
electron acceptor.
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- Summer '07
- Wishtichusen
- Membranes, Photosynthesis, primary electron acceptor
-
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