Unit 5, photosynthesis light dependent reaction Flashcards
Where does LDR take place?
In the thylakoid membrane
What are light energy and water used for?
Creating ATP, and creating reduced NADP
What are the 4 key stages in LDR?
1) photolysis of water
2) photoionisation of chlorophyll
3) chemiosmosis
4) production of ATP and NADP
What occurs in the photolysis of water stage of LDR?
- light energy is absorbed and is splitting the water into H+, oxygen and e-
What is oxygen used for in the photolosysis of water?
Respiration, or diffuses out of the leaf through stomata
What is the h+ used for in photolysis of water?
H+ is picked up by a NADP to form NADPH to be used in LIR
What are the electrons used for in photolysis of water?
They are passsed along a chain of electron protein carriers
What happens in the photoionisation of chlorophyll stage?
- light energy is absorbed by chlorophyll, which is then picked up by electrons chasing the electrons to be excited, raising electrons energy levels
- causes chlorophyll to be ionised
- some energy goes to the making of ATP and reduced NADP in chemiosmosis
What happens in the Chemiosmosis stage?
1) electrons that gained energy move along a series of proteins embedded within the thylakoid membrane ( an electron transfer chain)
2) as they move along they release energy , some energy is used for pumping protons across chloroplast membranes, protons within stroma go to the thylakoid membrane by active transport
3) a high concentration of H+ in inter membrane space causes there to be an electrochemical gradient to be created. Protons can now pass through enzyme to form ATP synthase, which results in ATP production through diffusion
4) reduced NADP is formed by the protons moving from high to low gradient (chemiosmosis), some protons are picked up by co enzyme NADP, it becomes reduced due to picking up proton and electron. Some protons are recycled through the cycle
