3.5.1: Photosynthesis Flashcards
What are the two stages of photosynthesis?
-Light dependent reaction
- Light independent reaction
Describe the LDR
1) Photoionisation. Chlorophyll absorbs light energy. Excites electrons. Chlorophyll is oxidised.
2) Electrons moves down electron transport chain releasing energy. Energy released to forms proton electrochemical gradient.
3) Photophosphorylation. H+ ions disuse through ATP synthase providing energy to join ADP and Pi to form ATP
4) Photolysis. H2O -> 2e- + 2H+ + 1/2O2. NADP reduced by hydrogens. Electrons replaces those lost
Where does the LDR occur?
Thylakoid membrane
Where does the LIR occur?
stroma
Why is LIR temperature sensitive?
Contains enzymes
Describe LIR
1) Fixation - RuBP combines with CO2 using the enzyme rubisco to form two GP.
2) Reduction - GP is reduced to TP using H from NADPH and energy from ATP. Some TP converted into useful organic products e.g. carbohydrates, amino acids and triglycerides
3) Regeneration - Most TP is regenerated back to RuBP using energy from ATP