Gen. Bio. Quiz 2: Light-Dependent Reaction Flashcards
Light-dependent reactions
a. requires _________
b. occurs in the _____________
c. involves two _________ and an _________
a. sunlight
b. thylakoid membrane
c. photosystems; electron (e-) transport chain
Large complexes of proteins and pigments (light absorbing molecules) that are optimized to harvest light.
Photosystems
What are other names for photosystem I and photosystem II?
PSI: P700
PSII: P680 (functions first)
4 main processes of light-dependent reaction:
- Light absorption in PSII
- ATP Synthesis
- Light absorption in PSI
- NADPH Formation
What is the special pair of chlorophyll a molecule?
Reaction-center Complex/Chlorophyll
Process.
a. Once photon is absorbed, energy is transferred from one pigment molecule to another until it
reaches the reaction center chlorophyll.
a. Resonance Energy Transfer
Process.
b. Electron is elevated to an orbital (high PE), which makes it __________
c. Once excited, chlorophyll electron is _______ and cannot stay long.
b. excited
c. unstable
Process.
d. Electron is now transferred to primary electron acceptor called ___________.
Pheophytin
Process.
e. The electron will be passed on
through the first leg of the electron
transport chain in a series of
____________
e. redox (electron transfer) reactions
Process.
f. The resulting P680 is missing negative charge of an electron, thus the solution is ___________ that happens in the ____________.
f. Photolysis; Thylakoid Lumen/Space
Photolysis. An enzyme catalyzes
water to split into:
- 2 electrons
- 2 Hydrogen ions (H+)
- 1 oxygen atom
Process.
g. From the pheophytin, the electron is now transferred to PSI via the ____________.
electron transport chain
Four proteins present in the electron transport chain:
Plastoquinone (Pq)
Cytochrome Complex (cyt)
Protein-plastocyanin (Pc)
Ferredoxin (Fd)
Process.
h. The electron transport chain releases _________.
i. the same process happens in _________ as it does in PSII
h. free energy
i. Photosystem I (PSI)
Process.
j. Electrons are passed in a series of redox reactions down to the ETC through the protein ___________.
ferredoxin (Fd)
Process.
k. ___________ catalyzes the transfer of electrons from Fd to NADP+
l. ___________ are needed
to reduce NADP+ to NADPH
k. NADP+ Reductase
l. two electrons
Process.
The energy from the electron fuels membrane pumps that actively move hydrogen ions against their concentration gradient from the stroma into the thylakoid space.
In the electron transport chain
Specifically CYTOCHROME COMPLEX
Process.
* Hydrogen ions build up in thylakoid space.
* This potential energy is harvested and stored as chemical energy in ATP through chemiosmosis.
Electrochemical Gradient
Process.
The movement of hydrogen ions down their electrochemical gradient through the transmembrane enzyme ATP synthase.
Chemiosmosis
Electrons loop back to the first part of the electron transport chain, repeatedly cycling through PSI instead of ending up in NADPH.
Cyclic Photophosphorylation
ATP Synthesis relies on the _________, thus when protons leak into the stroma and ruin the gradient, it also ruins the process of ATP synthesis.
proton gradient
The process that occurs in PSI only and generates ATP.
Cyclic Photophosphorylation
