Oxygenic Photosynthesis Flashcards
what is photosynthesis
conversion of light energy to chemical energy and reducing power
what does NADP+ reductase form
NADPH
what do thylakoids stack up to form
grana (singular = granum)
what is the chloroplast equivalent of the cytosol called
stroma
why are chloroplasts green
they reflect the green wavelength of photosynthetically active radiation
chlorophyll a and b absorb and use blue and red light so all that is reflected back is green
what allows chlorophyll to associate with the lipid thylakoid membrane
lipophilic isoprenoid chain
what part of chlorophyll absorbs light energy
how is this possible
pyrrole ring structure
energy delocalises electrons which then exist in a cloud around the ring and are not bound to one atom
where do light energy harvesting processes occur
across thylakoid membrane
what complexes are responsible for catching light
photosystems
how are electrons supplied to photosystem II
oxidising water to oxygen
photosynthesis summary (5 steps)
1) excitation of antenna chlorophyll
2) transfer of energy to reaction centre
3) primary charge separation event
4) electron transport chain forms electrochemical gradient to drive ATP synthesis and form NADPH
5) H2O oxidised to replenish reaction centre electron
what is chlorophyll
a specialized pigment embedded in the thylakoid membrane which absorbs light energy
how does chlorophyll absorb light
energy of photoexcitation delocalises electrons
what is the primary charge separation
the conversion of energy from physical to chemical state
describe the thylakoid electron transport chain
light is absorbed at the P680 photosystem II and electrons are passed to plastoquinone
energy difference transports 4 protons across the membrane
light is absorbed at P700 photosystem I and electrons are used by ferredoxin to turn NADP+ to NADPH
