8 Flashcards
Photosynthesis is separated into
- light reactions
- calvin cycle
the conversion of CO2 into an organic form is called— and how does it work
carbon fixation - a reduction reaction with electrons being added to CO2
where does photosynthesis take place in a cell
the cholorplasts
After the pigment molecule absorbs a photon of light in photosynthesis, one of three possible events can occur
- the excited electron returns to ground state and releases energy of a longer wavelength
- The energy of the excited electron is transferred to a neighbouring molecule in a process called inductive resonance
- the excited electron is transferred to an electron accepting molecule called a primary acceptor
Difference between absorption spectrum and action spectrum
The absorption spectrum shows which wave lengths are absorbed in each individual type of chlorophyll. The action spectrum shows which wavelengths of light are most effective for photosynthesis.
function of a photosystem
trap photons of light and use the energy to oxidize a reaction centre chlorophyll, with the electron being transferred to the primary electron acceptor
The 3 key events that take place within photosystem II
- The absorption of photons and energy to the reaction centre result in an electron within P680 being excited- now changed to P680*
- P680* can be oxidized to P680+ by the primary electron acceptor
- P680+ is reduced back to P680 by a donation of an electron from H2O
Linear electron transport
The pathway of electron flow from photosystem II through photosystem I to synthesize NADPH
3 main phases of one turn of the Calvin cycle are
- Fixation - CO2 is added to RuBP making a rubisco, and then split into two PGA’s
- Reduction - PGA is phosphorylated and then hydrogen is added to it.
- Regeneration - in a series of reactions, ATP is used to rearrange 5 G3P into 3 RuBP
summary of calvin cycle
CO2 is reduced and converted into carbs by adding electrons and hydrogen carried by the NADPH produced in light dependant reactions, ATP is also used
oxygen is a —– of rubisco
competitive inhibitor, it competes with CO2 for the active site
In aquatic photoautotrophs
an ATP process pumps bicarbonate into the cell which is converted to CO2 by a enzyme carbonic anhydrase