2.12 - The Light Reactions Flashcards
What are the 2 stages of photosynthesis?
The light reactions
&
The calvin cycle
What does NAPD stand for?
NADP
=
Nicotinamide adenine dinuleotide phosphate
The abreaviation of Nicotinamide adenine dinuleotide phosphate is?
NAPD
What does Pq stand for?
Plastoquinone
[plast-o-quin-own]
The short form for Plastoquinone is…?
Pq
What does Pc stand for?
Plastocyanin
[Plast-o-cy-anne]
The shortform for Plastocyanin is…?
Pc
What does Fd stand for?
Ferredoxin
[farah-docs-in]
What is the shortform for Ferredoxin?
Fd
Which photosystem comes first in the light reaction?
Photosysten II.
This is because it was discoved second but came first in the order
What happens in the Light Reaction of photosynthesis?
Give 8 main points (summary sheet)
1) Light enters photosystem II. energy exists as e- and gets passed around the antenna complex to chlorophyll-a in the rxn centre
2) Chlorophyll-a donates e- to primary electron receptor. e- gets replaced by splitting H2O. O2 gets released as waste and H+ stays in lumen
3) e- moves from primary electron acceptor to Pq. As it releases energy, it pumps out H+ into lumen (think oposite direction of ETC)
4) e- moves from Pq to cytochrome complex. It releases energy, then pumps out H+ into lumen
5) e- moves from cytochrome complex to Pc, then to photosystem I. e- replaces missing e- on chlorophyll-a in rxn centre of psI
6) light hits PsI & passes energy to rxn centre. Chlorophyll donates e- to primary electron acceptor
7) e- moves from PEA to Fd to NADP+ reductase. It trnasfers e- to NADP+ to make NADPH, which moves onto the Calvin cycle
8) H+ in lumen undergoes chemiosmosis. It passes through ATP synthase to leave the thylakoid as ATP. That ATP fuels the Calvin cycle
PsI or PsII = photosystem, PEA = primary electron acceptor
