Photosynthesis Flashcards
Define metabolic pathway
A series of small reactions controlled by enzymes
Define photophosphorylation
Using light to add phosphate to a molecule
Define photolysis
The splitting of a molecule using light
Define hydrolysis
Splitting a molecule using water
Describe the 5 key points in the light dependent reaction
-Light enters photosystem 2, where it excites the electrons and raises the energy levels -The electrons pass down the ETC in a series of redox reactions -Electrons reach NADP+ reductase where they combine with hydrogen ions and NADP+ to form NADPH -The water in the thylakoid inter-membrane space is photolysed , providing electrons to maintain the ETC gradient, producing 1/2O2 as a waste product and H+ ions -H+ ions pass through ATP synthase, producing ATP (then used in the Calvin cycle) and giving a high H+ concentration in the stroma. The H+ ions are then used to make NADPH
Where does the light dependent reaction take place?
In the thylakoid, which exist in stacks called granum
Describe the structure of a photosystem
Describe the structure of a chloroplast
Describe the structure of a leaf
Where does the Calvin cycle occur and why?
In the stroma due to the abundance of enzymes
What are the three limiting factors of photosynthesis?
-Light -CO2 -Temperature
What are the three limiting factors of enzymes?
-pH -Temperature -Quantity of substrate
Describe the Calvin cycle beginning from RuBP
-RuBP is a 5C chain, combines with CO2 -Forms an unstable 6C chain which splits immediately into 2 x GP (PGA) -ATP and NADPH from light dependent reaction react with the GP, ATP driving the reduction, to form 2 x TP -This cycle occurs six times to make 1 glucose and 5 RuBP
What is the significance of Rubisco?
-Enzyme for carboxylation -Most abundant enzyme on earth
