Chapter 8, Light Dependent Reaction (slides 31-46) Flashcards
Two major processes of photosynthesis reactions
- light dependent (energy-transduction)
- light independent (Carbon-fixation reactions)
Light-dependent reaction have to do with
energy transfer
In a light-independent reaction,
CO2 fixed to OR enzymatically combined with OR covalently bonded with RuBP
Photolysis is process of
water molecules getting split
Parts to light-dependent reactions are…(4)
- Noncyclic photophosphorylation
- Photolysis
- Chemiosmosis
- Cyclic Photophosphorylation
Noncyclic photophosphorylation
energy/electron transfer –> NADPH
Photolysis
splitting water
Chemiosmosis
making ATP
Cyclic Photophosphorylation
energy/electron transfer
Formula for light-dependent reaction
Water + Light –> NADPH + Oxygen + ATP
General step 1 of light-dependent reactions
- Light hits photosystem 1
- Transfers energy in photon to electron in one of pigment molecules
(Step 1) electron are energized by energy being passed to _____
P700
(Step 1) The P700 is the _______ ______
reaction center
(Step 1) Reaction center passes electrons to ________ then ______ _______
Feridoxin then NADP+ Reductase
(Step 1) NADP+ reduces it to _____
NADPH
(Step 1) One problem is that…
photosystem 1 will eventually run out of electrons and shut down
General Step 2 of light-dependent reactions
- light hits photosystem 2, transferring energy in photon to electron in pigment
(Step 2) Energy passed to _____
P680
(Step 2) The P680 is the ______ _____
reaction center
(Step 2) P680 passes electron to ________ _____
Redox Chain
(Step 2) Another name for Redox Chain
Electron Transport Chain
(Step 2) then redox (electron transport) passes electrons to…
photosystem 1 to keep it going
Step 3 is the _________ _______
Chemiosmotic Theory
(Step 3) The Chemiosmotic Theory is electrons passing through _____ ______ used to pump __________ _______ from _______ into ______________ lumen
through REDOX CHAIN used to pump HYDROGEN IONS from STROMA to THYLAKOID lumen
(Step 3) Hydrogen Ions diffuse _____ concentration gradient and pass through _____ ______
down, ATP Synthase
(Step 3/4) When ions diffuse and pass through ATP synthase, that makes ___
ATP
General step 4 is
ATP Synthase
(Step 4) H+ ions diffuse back into the ______ through _____ _____ making ____
stroma, ATP Synthase, ATP
ATP Synthase is a ________ protein
multimeric
ATP Synthase ______ as H+ ions pass, coupling H+ flow with ____ ____________
rotates, ADP Phosphorylation
ATP Synthase consists of…(3)
- base embedded in thylakoid membrane
- rotating shaft
- stationary head
ATP Synthase shaft rotates as H+ ions pass between the ____ and ____ subunits in the base
a and c
The rotation is ____ degrees
120
The 120 degree rotation causes _______ changes in the head
conformational
In the second, _____ and ____ are forced together, making ATP
ADP, Phosphate
In the third, ____ is released
ATP
Hydrogen Ion flow is _____ to ATP synthesis
coupled
light absorbed by photosystem 2 is also used to _____ water, generating _____ ____
split, oxygen gas
_______ are passed to photosystem 2 then _______ ________ ______
electrons, electron transport chain
_______ _______ added to those electrons pumped into the thylakoid membrane
hydrogen ions
Major products of Light dependent reactions
ATP, NADPH, Oxygen
Cyclic photophosphorylation is different because… (3)
- photons energize electrons only in photosystem 1 (P700)
- Electrons not passed to NADP+, but to extra Redox Chain
- this is only to make ATP, no NADPH or Oxygen
When H2O splits, created
2 electrons, 2H+, 1/2 O2
Water splitting only happens in Photosystem
two
non-cyclic produces
ATP and NADPH
cyclic produces
just ATP (photosystem one)
electrons travel from _____ to _____ energy states
higher to lower
