Photosynthesis Flashcards
What are this first step of photosynthesis
1) Photon absorption by PSII reaction center and generation of O2. 4 Electrons generated from 2 molecules
What is the second step of photosynthesis
electrons flow through the etc, including electron carriers PQ, PC and Cyt b6f
What is the third step of photosynthesis
Photon absorption by PSI reaction centre, final electron acceptor is NADP+
What is the fourth step on photosynthesis
Photophsophorylation occurs
What is the fifth step of photosynthesis
CO2 fixation in the calvin cycle to form G3P
Where is ATP synthesis occuring
In the stroma
What does the calvinc cycle produce
G3P and CO2
What does photosynthesis accomplish for the cell
Converts light energy to redox energy, used to generate ATP and reduce NADP to NADPH. Calvin cycle uses ATP and NADPH to reduce CO2 to form G3P
What is hte net reaction of the Photosynthetic ETC
2H2O + 8 photons + 2 NADP + 3ADP + 3Pi –> O2 + 2 NADPH + 3 ATP
What is the net reaction of the Clavin Cycle
3 Co2 + 6 NADPH + 9ATP + 5H2O –> G3P + 6 NADP + 9ADP + 8 Pi
What are the key enzymes in photosyntehsis
PSII, cytochrome b6f, PSI
Photosynthetic pigments absorb light in the _____ range of the spectrum
visible
carotenoids absorb in the ____ range which is why they appear _____
blue, orange
what are the major pigments in green plants
chlorophyll a, b and carotenoids
what is the role of LHC II
functions as a solar panel that harvests light energy for PSII and PSI
What is noncyclic electron transfer
Electron transfer from H2O to NADP to produce NADPH
2 electrons must be lifted twice
4 protons translocated
what is cyclic electron transfer
alternative path of electrons, electrons move from ferredoxin back to cyt b6f complex
What is the role of cyanobacteria
use cytochrome b6f, cytochrome c6 and plastoquinone for both oxidative and photoposphorylation
How many electrons are needed to reduce 2PQB to 2PQBH2
4
What happens in the PQ cycle
8 H are translocated in PSII and cytochrome b6f. 4H generated by oxidation of 2H2O to O2, leading to net gain of 12 H
What happens when NADP levels are high in the stroma
leads to electron flow between ferredoxin and plstiquinone in PSI
In mitochondria and bacteria protons are pumped ___ of the organelle, while chloroplasts protons are pumped ___ of the organelle
out, in
What is stage 1 of the calvin cycle
RuBP combines with CO2 , then cleaves two C3 molecules of 3-phosphoglycerate
What is stage 2 of the calvin cycle
3-phosphoglycerate is reduced to g3p using ATP and NADPH
What is stage 3 of the calvin cycle
5 G3P are used to resynthesize 3 ribulose 1,5 biphosphate in a carbon shuffle that requires ATP
G3P are building blocks for what?
for hexose sugars
What is the glyoxylate cycle in plants
provides a mechansms for fats stored in seeds to be converted to surcose for export
In chloroplast, ATP synthase releases newly synthesized ATP into the _____
stroma
What are the differences between Chlorophyll and Heme
Chlorophyll coordinates with Mg ion and has a hydrophobic tail, while Heme coordinates with Fe ion and lacks hydrophobic tail
for every four reduced PQBH2 molecules that are oxidized in PQ cycle, how many protons are translocated to the thylakoid lumen?
8
where are electron carriers from PSI stored
in the thylakoid lumen
Where does the CO2 come from that is used in the Calvin cycle
from the air
Calvin cycle inhibitors are more present in the dark or light?
dark
Calvin cycle enzymes are activated by a ______ in proton concentration and _______ in Mg levels in the stroma
decrease, increase
