Understanding Photosynthesis and Respiration: Energy Transfer and Storage

1. Photosynthesis & Respiration

2. Introduction Vocab • Energy-ability to do work • Autotrophs-organisms able to capture energy from sunlight and produce their own food (producer) • Heterotrophs-organisms that obtain energy from the food it consumes (consumer)

3. Energy • Comes in different forms: light, heat, & electricity • Made when electrons move from high energy orbitals to lower • How do we store and release/transfer energy? • ATP-adenosine triphosphate (tri=3) • Stores energy • ADP-adenosine diphosphate (di=2)

4. ATP & ADP • ATP-adenine, ribose, and 3 phosphate • ADP-adenine, ribose, and 2 phosphate • Energy is stored between the bonds of the 2nd and 3rd phosphate and transferred when broken ***ATP is the basic energy source of all cells -active transport -protein synthesis -muscle contractions -light produced by fireflies

5. ATP & ADP Continued… • Cells only have a small amount of ATP because it can’t be stored very well in the body • Cells are constantly regenerating ATP from ADP by using the energy in glucose • Glucose stores more than 90x chemical energy than ATP • Glucose is a product of photosynthesisand a reactant of respiration!!!

6. Requirements for Photosynthesis • 1. Light • “white light”-actually a mixture of different wavelengths of light • Ingenhousz & Priestly • Different wavelengths=different colors • 2. Carbon Dioxide-from environment • 3. Water-from environment • 4. Chloroplast • Plants gather energy from sunlight with pigments • chlorophyll (green) and carotene (reddish/orange) • Chlorophyll doesn’t absorb green…green light is reflected. • Remember: light is energy, so when light is absorbed so is its energy

7. Light & Pigments • As the chlorophyll in leaves decays in the autumn, the green color fades and is replaced by the oranges and reds of carotenoids. • 500-600nm-very little light is absorbed. • This light is in the green region of the spectrum, and since it is reflected plants appear green. • Chlorophyll absorbs so strongly that it can mask other less intense colors

8. Photosynthesis • Plants use the energy of sunlight to convert water and carbon dioxide into high-energy carbohydrates and produce oxygen as a waste product • 6CO2 + 6H2O  C6H12O6 + 6O2 • Carbon Dioxide + Water  Glucose + Oxygen • What’s missing???? • Light (energy) and Chloroplasts!!

10. Photosynthesis • Organelle: Chloroplast • Two reactions in photosynthesis • Light –Dependent • Calvin Cycle (Light-Independent)

12. Reactions of PhotosynthesisOrganelle: Chloroplast Light-dependent Light-Independent -Location: Thylakoid Membrane -Requires Light -Uses H20 -Produces Oxygen -ADP is converted to ATP -NADP+ is converted to NADPH -Location: Stroma -Light not required -Uses CO2 -Produces Sugars -ATP is converted to ADP -NADPH is converted to NADP+

13. Chloroplast

14. Light-Dependent Vocab • Photosystem-cluster of chlorophyll & pigments • Electron Transport Chain -chain of proteins that transfer high-energy electrons • Carrier Molecule -Compound that can accept a pair of high-energy electrons & transfer them to another molecule (NADP+ accepts electrons & H + ion, which turns it into NADPH)

15. Light-Dependent Reaction • Location: Thylakoid Membrane (Chloroplast) • Step 1: Light absorbed by photosystem II is used to break up water molecules into energized electrons, hydrogen ions (H+), and oxygen

16. Light-Dependent Reaction • Step 2: High-energy electrons from photosystem II move through the electron transport chain to photosystem I. As they lose energy, H+ ions are forced from the stroma into the thylakoid membrane through a protein.

17. Light-Dependent Reaction • Step 3: Electrons released by PSII are energized again in PSI. Enzymes in the membrane use the electrons to form NADPH from NADP+.

18. Light-Dependent Reaction • Step 4: Inside the thylakoid there are many positively charged H+ ions. The outside of the membrane is negative. The difference in charge provides energy to from ATP.

19. Light-Dependent Reaction • Step 5: As hydrogen (H+) ions pass through ATP synthase (carrier protein), their energy is used to convert ADP into ATP. ATP Synthase has to rotate to bind the P & ADP (energy).

20. Light-Dependent Review Location: Thylakoid Membrane -Requires Light -Uses H20 -Produces Oxygen -ADP is converted to ATP (high energy) -energy stored -NADP+ is converted to NADPH (high energy) -energy stored

21. http://www.youtube.com/watch?v=Oi2_n2wbB9o&feature=relatedhttp://www.science.smith.edu/departments/Biology/Bio231/ltrxn.htmlhttp://www.youtube.com/watch?v=eY1ReqiYwYshttp://www.youtube.com/watch?v=Oi2_n2wbB9o&feature=relatedhttp://www.science.smith.edu/departments/Biology/Bio231/ltrxn.htmlhttp://www.youtube.com/watch?v=eY1ReqiYwYs

22. Recall:

23. Calvin Cycle (Light-Independent) • Location: Stroma • 1st-CO2 enters from the environment • 2nd-CO2 combines with 5-carbon molecule to form two 3-carbon molecules • 3rd-ATP and NADPH provide energy to rearrange the 3-carbon molecules into higher energy forms • ATP from Light-Dependent Reaction converted to ADP • NADPH from Light-Dependent Reaction converted to NADP+

24. Calvin Cycle Continued… • 3rd-The higher energy 3-carbon molecules have two options: 1. One will leave the Calvin Cycle to make sugars, lipids, or amino acids (so autotrophs can grow) or 2. Five others get converted back to 5-carbon molecules to go through the cycle again *Uses six CO2 molecules to make one glucose molecule (go back to the equation)

25. Calvin Cycle

26. Calvin Cycle Review • Location: Stroma in the chloroplast • Uses CO2 • ATP is converted back to ADP • Energy was released • NADPH is converted back to NADP+ • Energy was released

27. Photosynthesis Overview sunlight & water O2 Light Dependent Reactions NADPH ATP NADP+ ADP Light Independent Reactions Compounds for growth (Sugars) CO2