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Similar a Photosynthesis 2020 final.pptx.pdf
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Photosynthesis 2020 final.pptx.pdf
- 3. What is Photosynthesis • Photosynthesis is the trapping (fixation) of carbon dioxide and its subsequent reduction to carbohydrate using hydrogen from water. • Light energy to is converted to chemical potential energy This Photo by Unknown Author is licensed under CC
- 5. The Pigments Pigment groups Colour Chlorophylls Chlorophyll a (a pair reaction center) Yellow - green Chlorophyll b Blue - green Carotenoids β Carotene Orange xantophyll Yellow
- 6. Knowing the Pigments • Rf value: distance travelled by pigment spot divided by distance travelled by the solvent • Result will depend on the solvent used.
- 7. Knowing the Pigments •Rf value of carotenoids close to 1 •Rf value of chlorophyll b lowest value •Rf value chlorophyll a value between carotenoids and chlorophyll b
- 8. The Photosystem s • Photosystem I – main wavelength of light absorbed is 700 nm • Photosystem II - main wavelength of light absorbed is 680 nm
- 12. Action Spectra
- 13. Absorption VS Action Spectra • Similarities and differences (using composite line for absorption spectra)
- 14. Photosynthesis : The Big Picture 1 2 • Photosynthesis involves 2 sets of reaction: 1. Light dependent reaction 2. Light independent reaction
- 15. Harvesting Light Energy • When a photon strikes a pigment molecule in a light-harvesting complex, the energy is passed from molecule to molecule until it reaches the reaction-center complex. • Here, an excited electron from the special pair of chlorophyll a molecules is transferred to the primary electron acceptor.
- 16. Light Dependent Reaction: NON cyclic photophosphorylatio n This Photo by Unknown Author is licensed under CC
- 19. Summary of Light Dependent Reaction Happens in Thylakoid membrane Input: Water and Light Output: ATP, NADPH and Oxygen as a by product
- 21. Light Independent Reaction The end product of photosysnthesis isn’t really glucose; it’s TP (Triose Phosphate) . It can be used to manufacture glucose, or other sugars, fatty acids or amino acids. Photophosporylation @ thylakoid membrane🡪 ATP & NADPH (released in stroma) Calvin cycle completely happens @ stroma. It is sometime called dark reaction because it does not need light energy to happen but not necessarily only happens at night
- 22. 1 x2 glycerate-pho sphate X2 triose phosphate 1/6 of triose phosphate glucose, amino acid, etc 5/6 of triose phosphate
- 23. Main Limiting Factors LIGHT INTENSITY TEMPERATURE CARBON DIOXIDE CONCENTRATION
- 24. Light Intensity • Further than the limiting value, light is not a limiting factor anymore. • It may be the temperature or carbon dioxide concentration This Photo by Unknown Author is licensed under CC
- 25. Temperature • In light dependent reaction, temperature have no significant effect. • Only in Calvin cycle that temperature play major role, as this is a common enzyme-controlled reaction. • Interpret the graph!
- 26. Carbon Dioxide • In light dependent reaction, carbon dioxide had no significant effect. • Only in Calvin cycle that carbon dioxide play major role, as it is the substrate of Rubisco. • Interpret the graph!
- 27. Combination of Limiting factors • A to B • B to C • A to D • D to F • F to G
- 28. C4 and CAM Plants • Points to remember: • Plants always try to reduce transpiration • During daylight, light dependent reaction happens in maximum rate. • Plants can conduct Calvin cycle during daylight.
- 29. C4 and CAM Plants
- 30. C4 Pathway •Spatial separation of Calvin Cycle •Consequence of high temperature, enzyme?
- 32. CAM Pathway •Temporal separation of Calvin Cycle