Ch 10: Photosynthesis Flashcards
Light dependent reactions:
Use sunlight,
Occur in thylakoids
Input: H2O
Output: O2, ATP, NADPH
Light independent reactions
Doesn’t need sunlight: Calvin Cycle
Occur in stroma
Input: CO2, ATP, NADPH, water
Output: Chemical energy, ADP, NADP+, glucose.
Carotenoids
Act to “quench” free radicals by accepting or stabilizing unpaired electrons
Chlorophylls absorb:
Blue and red light and transmit green light
Carotenoids absorb:
Blue and green light and transmit yellow, orange, red light
Paper chromatography
Isolating pigments: grind leaves, pigment molecules move from leaves into solvent
Spot pigments on filter paper
Seperate pigments in solvent
= carotene, pheophytin, chlorophyll a, chlorophyll b, carotenoids
Action spectrum
Pigments that absorb blue and red photons are the most effective at triggering photosynthesis.
Fluorescence
Election drops back down to lower energy level; heat and flouorescence are emitted
Resonance
Energy in electron is transferred to nearby pigments
Chlorophyll molecules transmit energy from excited electrons in antenna complex to a reaction center
Chlorophyll and b carotene in antenna complex
Reduction/oxidation
Electron transferred to a new compound
Reaction center to electron accepter
Photosystem 2
Excited electrons feed an electron transport chain
Pheophytin (electron accepted) to Plastoquinone to cytochrome complex
Input: H2O
Output: oxygen, protons, ATP( via proton motive force),
Photosystem 2 and the cytochrome complex located
In the thylakoid membranes
Photosystem 1,2 ATP synthase and cytochrome complex
Found in thylakoid membrane,
No exact order
Null hypothesis of photosynthesis
When wavelength are combined the rate of photosynthesis will lot be double the maximum rate observed for each wavelength independently
^ true
Wavelengths more than doubles the rate of photosynthesis
Z scheme
Photosystem 2, pheophytin, plastoquinone, cytochrome complex, plastocyanine, photosystem 1, ferredoxin.
Photosystem 1,
Chlorophyll to ferredoxin (electron transport chain) to plastoquinone and repeat
Input: 2 photons, 2 electrons, NADP+, H+
Output: NADPH
What intermediates are produced as carbon dioxide is reduce to sugar?
No hypthesis and no prediction
results: 3 phosphoglucerate is first intermediate product. Other intermediates appear later.
Calvin cycles three phases occur
In the stroma of chloroplasts
Fixation (first step of Calvin cycle)
3RuBP + 3CO2 —> 6 3-phosphoglycerate (3 carbon)
Reduction of 3-phosphoglycerate to G3P
6 3-phosphoglycerate + 6 ATP + 6 NADPH —> 6 G3P + 6ADP + 6 Pi+ 6 NADP+ + 6 H+
- 1 G3P goes to creating glucose
Regeneration of RuBp from G3P
5G3P + 3 ATP —> 3 RuBP (5 carbon sugar) + 3 ADP + 3 Pi
Rubisco
Slow enzyme,
Slowness may be why there is so much in a plant ( 10%)
during photosynthesis
Rubisco catalyze Reaction with CO2
RuBP + CO2—> 2 3-phosphoglycerate
Used in Calvin clycle
During Photorespiration
Rubisco catalyze Reaction with oxygen
RuBP+ O2–> 1-3 phosphoglucerate (used in Calvin) + 1 2- phosphoglycerate( CO2 released and ATP used)
