dependent light reactions Flashcards
photoexcitation
when photons are absorbed by photosystem II in the antenna complex and gets transferred to the P680 molecule; one electron for every photon absorbed moves from the ground state to an excited state
photosystem (P700)
when the electrons from the cytochrome complex are transferred to P700 via plastocyanin. another photon is required for an electron to be released from P700 and pulled to the primary electron acceptor in Photosystem I.
photosystem (P680)
(3)
- very electronegative and can split water molecules
- P680 becomes oxidized and the electrons move to a PEA
- electrons and an enzyme subunit called the water splitting complex reduce P680+ to P680 returning it to its neutral state and able to be oxidized again
PEA- primary electron acceptor
cyclic electron flow
(2)
- when the electrons are transferred to ferredoxin, instead of being oxidized and transferring electrons to NADP+, ferrodoxin transfers the electrons to PQ
- pumps H+ into the lumen which is used to drive ATP synthesis
purpose of NADPH
location, reduced, oxidized
- located in light dependent
- it is reduced by NADP+ reductase (2H+ + NADP+)
- it is oxidized in the calvin cycle (1,3 BPG—G3P)
purpose of ATP
provides energy for the plant; energy needed in the Calvin Cycle to make G3P
cyclic electron flow and why it happens
it occurs when there is a low ATP production and high NADPH production; focuses on producing more ATP
product of P680
for every 1 H2O molecule, 2e- go to P680, 2H+ remain in the thylakoid lumen, and 1/2 O2 is a waste product
THATS HOW WE BREATHE!!
3 ways to create a proton motive force (chemiosmosis)
- protons taken into the lumen by redox reations of PQ
- protons are added due to water splitting inside the lumen
- protons are removed from the stroma to make NADPH, which decreases the concentrstion of protons in the stroma compared to inside the lumen (cytochrome complex)
