Flashcards in Lecture 11 Deck (15):
How is chlorophyll capable of absorbing photons?
The porphyrin ring possess a magnesium ion and an alternating single and double bonds. The system of double bond (resonance) is able to channel the energy absorbed.
Where does photosynthesis occurs?
In the photosystems present in the thylakoid membrane
What does photosystem contains?
chlorophyll-a, associated pigments and accessory proteins required to carry out photosynthesis
Photosystems are made of...
antenna complex and reaction centres
What is the role of the antenna complex?
capture and transfer the energy from light to the reaction centre
Where do the light dependent reactions occur?
In the thylakoid and the thylakoid membrane
What is the first step?
Primary photoevent: pigments are excited by a photon
What is the second step?
Charge separation: energy is transferred to the reaction centre, where an electron is transferred to an electron acceptor
What is the third step?
Electron transport: electron transport chain = create proton gradient and use to reduce the final electron acceptor NADPH
What is the complete reaction?
Photosystem 2 >> quinone >> plastoquinone >> b6-f complex >> plastocyanin >> photosystem 1 >> quinone >> ferredoxin (NADP >> NADPH)
What donates an electron to the quinone?
How many photons it requires to complete the oxidation of 2 molecules to produce molecular oxygen (2 electrons per water)
What is b6-f complex?
a proton pump and it uses the energy from the electrons to pump H+ into the thylakoid lumen
What is ferroredoxin?
it donates the electrons to NADP+ creating NADPH via the enzyme NADP reductase