6. Chloroplast Flashcards
give an example of a photoautotroph
cyanobacteria
how did a photosynthesising cell occur
a eukaryotic cell endocytose a cyanobacteria resulting in an endosymbiotic relationship forming
→cyanobacteria produce glucose for the cell
→the eukaryotic cell provides a safe secure environment
summary:
1) what is found in the stroma
2) the thylakoid membrane forms dense stacks called…?
3) where does light energy get converted into chemical energy?
4) describe the chloroplast membrane
1) starch granules
2) grana
3) thylakoid
4) double membrane (envelope)
where does the Calvin cycle occur
in the stroma
what are the two stages of photosynthesis
the light reaction and the Calvin cycle
where does the light reaction occur
in the thylakoid membrane
describe the process of the light reaction
1) chlorophyll absorbs light
2) electrons and hydrogen are transferred to the electron carrier NADP+
3) NADP+ becomes NADPH
4) ATP generated from ADP + Pi
what happens to water during the light reaction
water splits and oxygen is given off
how is light energy absorbed by the chlorophyll
pigment absorbs photons (light energy)
causes an electron to be elevated to a higher energy level
list 3 pigments
chlorophyll A
chlorophyll B
carotenoids
what is the one and only pigment involved in the light reactions
Chlorophyll A
what then happens to the elevated electron in the light reaction
the primary electron acceptor traps the high energy electron before it can drop back down
what is the reaction centre
a localised pair of chlorophyll A molecules which donate excited electrons to the primary electron acceptor
where is the primary electron acceptor found
thylakoid membrane
what two components form a photosystem
the primary electron acceptor and reaction centre
what is the wavelength of light absorbed in photosystem 1
700nm
what is the wavelength of light absorbed in photosystem 2
680nm
what happens when photosystem 2 becomes excited
1) gives 1 electron to the primary acceptor
2) the electron passes to the electron transport chain
3) P700 accepts the electron- this generates energy which is used to pump H+ ions out of the thylakoid membrane
what is the H+ gradient generated used for
used by ATPsynthase to produce ATP
then p680 gets oxidised. what does this mean?
splits a water molecule to gain electrons and generate oxygen
which photosystem does cyclic electron flow occur in
photosystem 1
describe the process of cyclic electron flow
electrons are passed from a. primary electron acceptor through a chain until it returns to p700. at each step electrons lose energy, this is used to pump H+ ions across the membrane= gradient
→ATPsynthase uses this to generate ATP
what is not produced from cyclic electron flow
NADPH or oxygen
where does the Calvin cycle occur
in the stroma
