3bio2 Flashcards
Photosynthesis light dependent reactions
-absorption spectrum
-action spectrum
-Antennae complexes
-what has to go in
-chain of passing electrons
-Z scheme
-cyclic and non cyclic flow
-what comes out
The amount of light that a pigment can absorb across the visible spectrum is the absorption spectrum. The rate of photosynthesis at various wavelengths is the action spectrum. Antenna complexes are aggregates of pigment molecules. ADP, NADP+, light and water go in. Light is the activation energy and excited electrons are passed to a pigment molecule called a reaction centre. Two reaction centers are photosystem II and photosystem I. Photosystem II Passes électrons to an ETC and does photolysis to replace them, releasing oxygen. Plastoquinone transports the electrons to the cytochrome complex, and plastocyanin transports them from there to photosystem I. Ferredoxin then transports them to NADPH reductase, which turns NADP+ into NADPH. The NADPH goes on to the Calvin cycle, but the calvin cycle needs twice as much ATP as NADPH. ATP is made by ATP synthase, powered by the movement of H+ across the membrane. The thylakoid space has more H+ than the stroma because of photolysis, plastoquinone had been transporting H+ in. The Z scheme is a hybrid of an energy diagram and a pathway model. When electrons are passed to NADP+ reductase it’s non cyclic flow. Cyclic electron flow is when Ferredoxin passes electrons back to Plastoquinone. ATP, NADPH and oxygen come out. Everything goes the the calvin cycle, except The oxygen which goes to the atmosphere.
Relevant light facts
-wavelength
-photoexcitation
The form of electromagnetic energy is determined by the wavelength of a photon. Wavelength is inversely related to energy. When light hits a surface it can be reflected, absorbed or transmitted. Light absorption causes photoexcitation, which is when a photon jumps to a higher energy level after absorbing a photon. It will only do this if the difference between the energy level it jumps to and the one it is in is equal to the energy of the photon. The opposite is fluorescence. Common plant pigments are chlorophyll A, chlorophyll B and carotenoids.
