1. Photosynthesis A Study of Life’s Complexities

2. Light Definitions Light behaves like a particle Light behaves like a particle –Photon – Discreet bundle of radiation Light behaves like a wave Light behaves like a wave

3. Properties of Light Absorbed: Absorbed: Reflected: Reflected: Transmitted: Transmitted:

4. Electromagnetic Spectrum See Overhead See Overhead

5. Visible Light In the electromagnetic spectrum, we can only see the visible light portion In the electromagnetic spectrum, we can only see the visible light portion What color of light is reflected from an orange shirt? What color of light is reflected from an orange shirt? What color(s) of light are absorbed by an orange shirt? What color(s) of light are absorbed by an orange shirt?

6. Light and Prisms When white light strikes a prism, the wavelengths separate and we see all the different colors When white light strikes a prism, the wavelengths separate and we see all the different colors

7. What is Photosynthesis The conversion of Light, Carbon Dioxide and water into Glucose The conversion of Light, Carbon Dioxide and water into Glucose Carbon Dioxide Water Glucose Oxygen

8. Pigments Chloroplasts contain several different pigments that absorb and reflect different wavelengths of light Chloroplasts contain several different pigments that absorb and reflect different wavelengths of light

9. Absorption Spectra

10. Pigments Chlorophyll A: Absorbs mainly in the violet and red Chlorophyll A: Absorbs mainly in the violet and red Chlorophyll B: Absorbs mainly in blue and orange Chlorophyll B: Absorbs mainly in blue and orange Carotenoids: Absorb mainly in the green and blue Carotenoids: Absorb mainly in the green and blue

11. Closing Questions Why are there so many pigments? Why are there so many pigments? Why do plants appear green in the summer and change colors during the fall? Why do plants appear green in the summer and change colors during the fall?

12. The Nut’s and Bolts Light Dependent Light Independent NADPH ATP NADP ADP

13. Products of Light Reaction ATP (Adenosine Tri-Phosphate) ATP (Adenosine Tri-Phosphate) –Carries energy to dark reaction –ADP (Di) is converted into ATP by ATP synthase NADPH (Nicotinamide Adenine Dinucleotide Phosphate) NADPH (Nicotinamide Adenine Dinucleotide Phosphate) –Carries electrons and protons (H + ) to dark reaction

14. Basics of Photosynthesis Photosynthesis occurs within the chloroplasts of plants Photosynthesis occurs within the chloroplasts of plants

15. Components of Light Reaction 2 Photosystems: Collection of pigments 2 Photosystems: Collection of pigments –Photosystem II happens before PS I –Hold chlorophyll and carotenoids Electron Transport Chain (ETC) Electron Transport Chain (ETC) –Chain of molecules that pass down electrons –The movement of electrons results in a negative charge which propels H+ atoms through the thylakoid membrane

16. Light Reaction PS 2 PS 1 ETC Electrons Sunlight strikes PS 2 and excite electrons that flow down the ETC The electrons cause a negative charge and propel H + into the thylakoid Exhausted electrons reach PS 1 and get excited again by sunlight Excited electrons flow onto NADP  NADP - NADP

17. Light Reaction PS 2 PS 1 ETC Water  2H + + O + e - Water splits in the thylakoid to form  2 Hydrogens (Accumulate in thylakoid)  1 Oxygen (Released into atmosphere)  2 Electrons (Pumped back into PS 2)

18. Light Reaction PS 2 PS 1 ETC Hydrogens accumulate in thylakoid and begin going through ATP Synthase ADP from dark reaction is turned into ATP with help of ATP Synthase ATP travels to Dark Reaction carrying Energy H+H+ ADP ATP

19. Light Reaction PS 2 PS 1 ETC The negatively charged NADP picks up a proton and becomes NADPH NADPH carries electrons and protons to the dark reaction NADP - NADPH H+H+

20. Light Reaction: 2 Choices Deals with the path the electrons take –Non-cyclic Pathway PS II  ETC  PS I  NADPH PS II  ETC  PS I  NADPH Results: NADPH + ATP Results: NADPH + ATP –Cyclic Pathway PS II  ETC  Back to PS II PS II  ETC  Back to PS II Results: ATP but NO NADPH Results: ATP but NO NADPH –No Dark reaction

21. The Dark Reaction Does not require Light Does not require Light Also known as the Calvin Cycle Also known as the Calvin Cycle Occurs within the stroma of the chloroplasts Occurs within the stroma of the chloroplasts Uses NADPH and ATP from light reaction and CO 2 from the atmosphere to create GLUCOSE Uses NADPH and ATP from light reaction and CO 2 from the atmosphere to create GLUCOSE

22. The Dark Reaction: Calvin Cycle RuBP – Ribulose Bis-Phosphate (4C’s) RuBP – Ribulose Bis-Phosphate (4C’s) PGA – Phosphoglyceric Acid (3C’s) PGA – Phosphoglyceric Acid (3C’s) PGAL or G3P– Phosphoglyceraldehide (3C’s) PGAL or G3P– Phosphoglyceraldehide (3C’s) Glucose – 6C’s Glucose – 6C’s It takes 6 turns of the cycle to form one glucose It takes 6 turns of the cycle to form one glucose

23. Leaf Structure

24. The Calvin Cycle But how does carbon dioxide get into the cycle???

25. Problems with the Dark Reaction RUBISCO – Can bond to CO2 or Oxygen RUBISCO – Can bond to CO2 or Oxygen –Ribulose Bisphosphate Carboxylase Oxygenase If RUBISCO bonds to Carbon Dioxide: If RUBISCO bonds to Carbon Dioxide: –Photosynthesis occurs – Glucose is made If RUBISCO bonds to Oxygen If RUBISCO bonds to Oxygen –Photorespiration occurs – Glucose is broken down to make energy

26. Other Problems that may occur Some plants live in hot climates and must close their stomates during the day Some plants live in hot climates and must close their stomates during the day –Why? –How does this affect the plant negatively?

27. Photosynthetic Pathways C3 pathway C3 pathway C4 pathway – Separation based on distance C4 pathway – Separation based on distance CAM pathway – Separation based on time CAM pathway – Separation based on time All have their benefits, all have their limitations All have their benefits, all have their limitations

28. C3 Plants Type of climate: Type of climate: Stomate strategy: Stomate strategy: Photorespiration strategy: Photorespiration strategy: Type of Plants Type of Plants

29. C4 Plants – Separation based on Distance

30. C4 Plants Type of climate: Type of climate: Stomate strategy: Stomate strategy: Photorespiration strategy: Photorespiration strategy: Type of Plants Type of Plants

31. CAM Plants – Separation Based on Time

32. CAM Plants Type of climate: Type of climate: Stomate strategy: Stomate strategy: Photorespiration strategy: Photorespiration strategy: Type of Plants Type of Plants