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Photosynthesis

Photosynthesis. Using the sun to make useful forms of energy. Very Important biologically!.

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Photosynthesis

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  1. Photosynthesis Using the sun to make useful forms of energy

  2. Very Important biologically! • Sunlight plays a much larger role in our sustenance than we may expect: all the food we eat and all the fossil fuel we use is a product of photosynthesis, which is the process that converts energy in sunlight to chemical forms of energy that can be used by biological systems.

  3. How does this occur • Various forms of radiation surround us, from the sun and other sources. • Some are visible and some are invisible.

  4. Wave model of light • Electromagnetic radiation travels at 300000000m/s • Frequencies of visible radiation (light) are perceived as different colours

  5. Wave model of light • Highest frequency is  violet • Lowest frequency is  red • All frequencies give white light

  6. Photon model of light • Light travels in energy packets called photons • Photons travel at 300000000m/s • The amount of energy in a photon depends on the frequency of the light • Light can transmitted reflected or absorbed • Air, water ….mirror…plants

  7. Pigments • Pigments absorb light of specific wavelengths (colours) of light • Pigments can be extracted from plant leaves • If plants are green what colour do they absorb, reflect, or transmit?

  8. Chlorophyll Pigments • There are 2 types of cholorophyll • Yellow - green • Blue – green • Found in the highly folded plant organelle

  9. Molecular model of chlorophyll

  10. Chlorophyll Absorption

  11. Chloroplasts • They are extremely small but perform thousands of reactions in each minute because of their highly folded thylakoid membrane inside the chloroplast.

  12. Plants are the only photosynthetic organisms to have leaves (and not all plants have leaves). A leaf may be viewed as a solar collector crammed full of photosynthetic cells.

  13. Photosynthesis in plants • Light energy is used to transform carbon dioxide and water to energy rich food molecules composed of glucose monomers

  14. How many Stages? • There are 2 stages in this process

  15. Overview of the two steps in the photosynthesis process

  16. Light Stage • The photosynthetic process in which solar energy is harvested and transferred into the chemical bonds of ATP; can occur only in light • Light dependent • Supplies Chemical energy (ATP) for the synthesis stage

  17. Photosystem • Where clusters of chlorophyll pigments within the thylakoid membrane

  18. Photostage • Light photons hit the photosystems and excite electrons. This energy is passed from one pigment molecule to the next. • The energy reaches a special pair of chlorophyll molecules that function as a reaction centre • The reaction centre uses the energy to split H2O • The resulting products are NADPH and ATP

  19. Synthesis Stage • It takes place in the stroma of the chloroplast and is called the Calvin cycle • The Calvin cycle needs energy from the photostage in order to happen! • The reactant used is CO2 and product is PGAL (glyceraldehyde phosphate) which can be bonded together to form glucose.

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