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Flashcards in Photosynthesis Deck (26):
1

Photosynthesis equation

6 CO2 + light + 6H20 -> C6H12O6 + 6 O2 + 6 H20
G= 686 kcal/mol

2

Mesophyll cell

Cell that contains chloroplasts; site of photosynthesis

3

Stroma

Fluid inside mesophyll cell; site of Calvin cycle

4

Thylakoid

Stacked chlorophyll-containing sacs inside of mesophyll cell
Thylakoid membrane: site of light reactions
Thylakoid space: site of proton gradient

5

Stomata

Pores in leaf through which CO2 enters and O2 leaves

6

Granum

Stack of thylakoids

7

Light absorption by pigment

Light stays in that state for a short amount of time, then dissipates
Dissipation- some energy is lost as heat
After absorption: fluorescence, heat, or resonance transfer

8

Fluorescence

Emitting a photon lower in energy than what was absorbed

9

Structure of chlorophyll

Porphyrin ring: absorbs photons
Hydrocarbon tail: anchored to thylakoid membrane

10

Absorption spectra

Light waves that are absorbed

11

Action spectrum

Light waves that are used for photosynthesis

12

Endosymbiotic theory

Chloroplasts and mitochondria are of prokaryotic origin

13

Chloroplasts and mitochondria have their own...

DNA, DNA polymerase, RNA polymerase, Ribosomes, Ribosomal RNA

14

Non-cyclic electron transport (light cycle)

H20 split to form 2 electrons -> 2 photons of light excite electrons in photosystem II -> electrons are transferred from P680 to primary acceptor -> plastiquinone -> cytochrome complex, pumping through membrane H+ needed to make ATP -> plastocyanin -> 2 photons of light excite electrons in photosystem I -> electrons are transferred from P700 to primary acceptor -> ferredoxin -> NADP+ reductase reduces NADP+ to NADH

15

Cyclic electron flow

Electrons in PS I -> primary acceptor -> ferredoxin -> cytochrome complex (creates ATP) -> plastocyanin -> PS I
Used when NADP+ is low (plant has been doing lots of photosynthesis)
2 H+ instead of 4 from cytochrome complex: less efficient than non-cyclic transport

16

Amounts of products produced in light reaction

1.5 H+/ photon
4 H+/ ATP
4 photon/ NADPH
Per light reaction: 4 photons, 2 electrons, 6 protons
3 ATP created (2 light cycles)

17

Calvin cycle

Phase 1 (carbon fixation): Rubisco turns 3 CO2 into 3-phosphoglycerate (3PG)
Phase 2 (reduction): 3PG + 6 ATP -> 1,3-bisphosphoglycerate
1,3-BPG + 6 NADPH -reduction> glyceraldehyde 3-phosphate (G3P)
Phase 3 (regeneration): G3P + 3 ATP -> ribulose bisphosphate (RuBP)
Per cycle: 9 ATP and 6 NADH consumed

18

Primitive bacteria

Developed first ATP-driven proton pump

19

Photorespiration

Rubisco adds O2 when CO2 is scarce (much more O2 than CO2 in atmosphere)
Occurs under light conditions
Doesn't make ATP
C3 plants: 1 in 3 times, rubisco fixes O2 instead of CO2
Decreases photosynthesis
Releases CO2
Increases when stomata close (conserve H2O) and temperatures increase

20

C4 plants

1st stable compound in pathway has 4 carbons
Mesophyll cells, bundle-sheath cells (storage of CO2- impermeable, so it can't escape), vascular tissue
Spatial separation in pathway

21

C4 photosynthetic pathway

Mesophyll cell: PEP carboxylase -> oxaloacetate -> malate -> pyruvate -> PEP (ATP used to make)
Bundle sheath cell: malate -> CO2 -> Calvin cycle -> sugar transported to vascular tissue
1 extra ATP is used per fixed CO2- as a result, plants use more cyclic electron flow to create more ATP

22

CAM plants

Desert plants
Stomata open at night
Temporal separation in pathway
2 mesophyll cells

23

CAM photosynthetic pathway

Night: PEP carboxylase fixes CO2- creates organic acids
Day: CO2 is used to fuel Calvin cycle and make sugar

24

Photosynthetic rates of plants

C4 > C3 >> CAM
C4 = 2*C3

25

Antenna complex

Part of thylakoid membrane that contains the most chlorophyll
Photon of light is transferred from chlorophyll molecule to chlorophyll molecule and eventually to reaction center

26

Reaction center

Center of photosystem that contains the special pair of chlorophyll molecules (P680 and P700)
Electrons are transferred from here to primary acceptor