Lecture 2 & 3 Photosynthesis I & II Flashcards
Autotrophs
Produce organic molecules from co2 and other raw inorganic materials (primary producers of biosphere)
Photoautotrophs
Use light as energy
Chemoautotrophs
harvest energy from oxidizing inorganic substances aka sulfur/ammonia (unique to bacteria)
Heterotrophs
consumers, live off organic compounds produced by others
Where are chloroplasts mainly found
Mesophyll cells, forming tissues in interior of leaf
What is stomata
Place where CO2 enters and 02 exits leaf
Veins
Deliver water from roots/ carry off sugar from mesophyll
Stroma
Contains membrous sacs (Thylakoids) which contain chlorophyll
Thylakoids stacked in columns called grana
Net process of photosynthesis
6CO2 + 6H2O + light energy —>
C6H12O6 +6O2
What is Photosynthesis
Redox Reaction, water split and electrons transferred with H+ from water to CO2, reducing it to sugar.
Polar covalent bonds converted to non polar
Two processes of photosynthesis
Light Reaction
Calvin Cycle
What is the light reaction process in photosynthesis
concerts solar energy to chemical energy
What is calvin cycle in photosynthesis
Turns CO2 into organic molecules and uses energy from light reaction to reduce new carbon piece to sugar
What’s happens in light reaction?
light enerygy absorbed by chlorophyll transfers electrons and hyrdrogen from water to NADP+, forming NADPH
also generates ATP by photophosphorylation for calvin cycle
Visible light
Most important segment for life, 380 to 750 nm
Chlorophyll a
dominant, absorbs red and blue wave lengths best, least in green
Chlorophyll b
slightly diff then chlorophyll a, funnels energy from wavelengths to chlorophyll a
Carotenoids
funnel energy from other wavelengths to chlorophyll a, and photoprotect against excessive light
What is energy of photon concerted to?
Potential energy of an electron raised from ground state to an excited state
Photosystem
light gathering antenna complex for chlorophyll and carotenoids molecules
Reaction center
contains primary electron acceptor which removes an excited electrons and starts light reactions
Absorbing light energy results in splitting of water then…
2 e- are realeased and flow to reaction center
Photosystem I
reaction centre with absorption peak at 700nm (P700 center)
Photosystem II
reaction center peak 680nm (diff proteins than other photosystem)
Both photosystem swirl together to generate….
ATP and NADPH using light energy
Noncyclic electron flow
- Reaction center oxidized when photosystem II absorbs light
- enzyme extracts electrons from water and gives to reaction center
- photoexcited elctrons pass long electron transport chain until arriving at Photosystem I reaction center
- ATP produced along transport chain by electrons
- At bottom of chain, electrons fill “hole” in P700 center
- Hole causeed by electrons passed from chain to NADP+ creating NADPH
Both photosystems use solar power to provide…
Chemical energy, ATP
Reducing power, NADPH
Cyclic Electron Flow
Pathway can be taken by photosystem I elctrons only
generate ATP by Cylclic Photophosphorylation along electron chain
Generates surplus of ATP
Chemiosmosis
elctron transport chain pumps protons across membrane while electrons pass
builds H+ gradient = Proton motive force
Atp synthase generate ATP from proton motive force
Mitochondria generate energy from….
Food molecules to ATP (Respiration)
Co2 enters The calvin cycle and it uses ATP and NADPH to make…
G3P
Each turn of calvin cycle fixes…
1 Carbon
Synthesis of G3P requires…
3 cycles and fixes 3CO2
Synthesis of one glucose requires…
6 cycles
3 Calvin Cycle Phases:
- Carbon Fixation
- Reduction
- Regeneration of the CO2 acceptor
Phase 1: Carbon Fixation phase of calvin cycle
Co2 attaches to 5 carbon sugar (RuBP) and catalyze day Rubisco. Splits in half and makes 2 molecules of Phosphoglycerate per co2
Phase 2: Reduction (Calvin Cycle)
2 3-phosphoglycerate molecules joined in atp reaction to for 1,3 Bisophoglycerate which is reduced by NADPH to form G3P
Phase 3: Regeneration of the Co2 (Calvin Cycle)
5 G3P molecules form 3 RuBP molecules, 3 ATP molecules needed to complete cycle and prepare for next
Net synthesis of 1 G3P molecule
Consumes 9 ATP and 6 NAPDH
3 ATP and 2 NADPH per CO2
