Photosynthesis Flashcards
Where do light reactions take place and what do they produce?
- they produce ATP and NADPH
- and it is in thylakoid membranes
What is NAD used for?
It is used to accelerate oxidation of sugars, [NAD] is kept high
What is NADHPH used for?
- it is used for reductions to make sugars
- [NADPH] is kept high
How does energy absorption work?
- it is electron transition to a higher energy level, which can facilitate chemical reactions. Low energy, high wavelength. vice versa.
What results in delocalized electrons?
- alternating/conjugated double bonds found in chlorophyll or beta carotene results in delocalized electrons - excited by certain wavelength of visible light
What are 3 things that may happen with excited electrons?
1) might fall back to ground state releasing light of slightly longer wavelength and heats
2) resonance energy transfer - physical process, energy released when a chlorophyll electron falls back to ground state, it is used to exite neighbouring chlorophyl molecule of slightly longer wavelength
3) transfer electrons - redox
In photosynthesis - which steps are redox and which are not?
- all initial steps from absorption of a photo until central chlorophyll is excited transfer of energy
- last step, electron transferred, redox reaction
What is the strongest oxidizing agent in biology?
- chlorophyll lacking an electron
What is the process of photosystem II and I?
- electrons released by photosystem II, move down electron transport chain and end up in photosystem I, where chlorophyll is excited and transferred to second electron transfer chain, which generates NADPH
Cyclic electron transport
- no water split
- no oxygen released
- PS I on its own
- plants use this when they have made enough sugar
Carbon fixation in stroma of chloroplasts
- describes conversion of C02 gas to sugar
- used up all of ATP and reducing power which is made in noncyclic electron transport
What is the difference between NAD and NADP?
- same properties, occurs in plants and animals, made by separate pathways and independently regulated