PHOTOSYNTHESIS L9 Flashcards
I. Intro to Photosynthesis - HD light and electrons II. Structures involved in Photosynthesis - CC components and structures III. Photosynthesis - CC PSI and PSII - CC types of e flow - SEQ, CC, HD stages of photosynthesis
1
Q
photoautotrophs
A
- use sunlight to make organic molecules from CO2
2
Q
photons
A
- particles of light E
- E inversely proportional to wavelength
3
Q
2 outcomes of energized electrons
A
- return to lower orbital (ground state) - emits heat and light
- leave atom, captured by acceptor - occurs in photosynthesis
4
Q
leaves
A
- main site of photosynthesis
5
Q
mesophyll cells
A
- photosynthetic cells
6
Q
chloroplasts
A
- primary eukaryotic photosynthetic organelle
7
Q
photosynthetic pigment
A
- captures light E for photosynthesis
- embedded in thylakoid membrane
- ex. chlorophyll a
8
Q
accessory pigments
A
- absorb wavelength of light not absorbed by chlorophyll a
- widen spectrum of light that can be absorbed
- ex. chlorophyll b, carotenoids
9
Q
why are plants green?
A
- pigments absorb specific wavelength
- light is not absorbed - its transmitted or reflected
- chlorophyll reflects and transmits green light
10
Q
photosynthetic redox reactions
A
- H2O oxidized
- CO2 reduced
- endergonic
- E input from sunlight
11
Q
light dependent reactions
A
- light E turns into chemical E (ATP and NADPH)
- occurs in photosystems
12
Q
photosystems 1&2
A
- protein complex containing pigments
- in thylakoid membrane
- capture light E
- transfer excited e
- produce ATP and NADPH
13
Q
light harvesting complex
A
- 250 chlorophyll molecules & accessory pigments, proteins
- transfer E from photon to reaction center
14
Q
reaction center complex
A
- has pair of chlorophyll a
- transfer e to primary e acceptor
15
Q
PSI
A
- chlorophyll a
- absorbs best at 700nm
- P700
16
Q
PSII
A
- chlorophyll a
- absorbs best at 680nm
- P680
17
Q
linear e flow
A
- light dependent
- PSII then PSI
- produces ATP and NADPH
18
Q
cyclic e flow
A
- light dependent
- only PSI
- produces only ATP
19
Q
photon absorption (linear e flow)
A
- 1st step
- photon hits pigment in PSII
- E passed among pigment molecules
- excites P680
- no e moving in this step
20
Q
e transfer (linear e flow)
A
- 2nd step
- excited e in P680 transferred to primary e acceptor
- P680 is oxidized
- now called P680+
- primary e acceptor reduced
- redox reaction
21
Q
H2O oxidation (linear e flow)
A
- 3rd step
- P680+ is an extremely strong oxidizing agent
- H2O is oxidized (photolysis)
- e transferred from H to P680+
- H+ released into thylakoid space
- P680+ reduced back to P680
- O2 released as byproduct
- this is where atmospheric O2 comes from
22
Q
electron transport chain (linear e flow)
A
- 4th step
- e from primary e acceptor goes through ETC from P680 to PSI
- generates H+ gradient
23
Q
ATP synthesis (linear e flow)
A
- 5th step
- H+ diffuses across thylakoid membrane thought ATP synthase
- drives ATP synthesis
24
Q
PSI E transport (linear e flow)
A
- 6th step
- light E excites e in pigments
- excites P700
- oxidized to P700+
- primary e acceptor reduced
- P700+ reduced back to P700 by e from ETC
25
Q
PSI ETC (linear e flow)
A
- 7th step
- e moves through PSI ETC to protein ferredoxin
- no H+ gradient generated
- no ATP produced
26
Q
NADPH synthesis (linear e flow)
A
- 8th step
- e transfered to NADP+
- NADPH synthesized
- released into stroma
- Calvin cycle
- catalyzed by NADP+ reductase
27
Q
carbon fixation reactions
A
- formation of carbohydrates from CO2
28
Q
Calvin cycle (C3)
A
- carbon fixation method used by most plants
- occurs in stroma
- does not directly require light
- does require ATP and NADPH from light dependent reactions
