Chapter 7 - Energy Acquiring Pathways Flashcards
How is photosynthesis important?
It uses water, sunlight and carbon dioxide into oxygen and sugars essential for plants
Which organisms perform photosynthesis?
Plants, algae and cyanobacteria
In eukaryotes, where does photosynthesis occur?
Chloroplasts
Explain photosynthesis in plants (phases).
Phase 1 (Thylakoid): Light-dependent reactions, where energy from light is tranferred to ATP and NADPH (energy carriers)
Phase 2 (Stroma): Calvin Cycle; Energy from ATP and NADPH used to build sugars from CO2
What are pigments molecules?
Pigment molecules absorb only certain wavelength. Other wavelenght are reflected, or transmitted (Ppl see the refelcted wavelenghts)
What is chlorophyll?
Chlorophyll is the most abundant pigment in green plants, absords 450 nm (blue) and 662 nm (red) wavelengths.
Gives color
What is photosystem?
Mechanisms in plants by which chlorophyll absorbs light energy for photosynthesis. There are 2 mechanisism (Photosystem I and II) involving different chlorophyll-protein complexes.
Within thylakoid membrane
Explain Photosystem I.
Primary electron acceptor?
Electron donor?
Final electron acceptor?
- (P700) Non-cyclic pathway (no rotation).
- Protein complexes tha uses light energy to transfer electrons across thylakoid membrane.
- Ferredoxin
- Chlorophyll
- NADP +
Explain Photosynthesis II (P680)
E from 2 photons transfers 2 electrons to primary electrons acceptor: Pheophytine
Electonrs tranfered to Plastoquinonr and Plastocyanin
(elec. carriers)
Electron donor: P680
Contribution to photon gradient
Non-cyclic phtophsophorylation
Photon used to power ATP, which is used in Calvin cycle
Photosystem 1 (P700): Cyclic pathway
ATP produced by cyclic photophosphorylation
No water needed, no O2 nor HADPH produced
