1 / 38

Chapter 8

Chapter 8. PHOTOSYNTHESIS. 8-1 Energy and Life. I. Energy is the ability to do work. Energy comes from food . A. Autotrophs and Heterotrophs 1. Plants and other organisms use light energy from the sun to produce food. 2. Autotrophs depend directly on the sun,

shanta
Download Presentation

Chapter 8

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 8 PHOTOSYNTHESIS

  2. 8-1 Energy and Life I. Energy is the ability to do work. Energy comes from food. A. Autotrophs and Heterotrophs 1. Plants and other organisms use light energy from the sun to produce food. 2. Autotrophs depend directly on the sun, whereas heterotrophs depend indirectly on the sun.

  3. 8-1 Energy and Life B. Chemical Energy and ATP 1. Adenosine triphosphate (ATP) – chemical compounds that cells use to store and release energy a. ATP consists of adenine, a 5-carbon sugar called ribose and three phosphate groups. b. three phosphate groups are the key to energy storage and release.

  4. ATP Adenine Ribose 3 Phosphate groups

  5. 8-1 Energy and Life 2. Storing Energy a. When a cell has energy to store, one phosphate is added to ADP making ATP. b.ATP is like a fully charged battery

  6. Comparison of ADP and ATP to a Battery ADP ATP Energy Energy Adenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP) Partially charged battery Fully charged battery

  7. 8-1 Energy and Life 3. Releasing energy a. Breaking the chemical bond between the 2nd and 3rd phosphate releases energy b. The characteristics of ATP make it useful and the basic energy source of all cells.

  8. 8-1 Energy and Life C. Using Biochemical Energy 1. ATP is used to carry out Active Transport in the cell membrane. ATP provides the energy that keeps the sodium-potassium pump working. It moves sodium out of the cell and potassium into the cell.

  9. 8-1 Energy and Life 2. ATP provides energy for motor proteins that move organelles. 3. Powers the synthesis of proteins and nucleic acids 4. ATP stores only small amounts of energy for a few seconds of activity.

  10. 8-2 Photosynthesis I. Photosynthesis - Plants use energy of sunlight to convert water and CO2 into high energy carbs. and oxygen (a waste product).

  11. 8-2 Photosynthesis A. Investigating Photosynthesis 1. Van Helmont’s Experiment a. Jan van Helmont experimented to see if plants grew by taking material out of the soil.

  12. 8-2 Photosynthesis b. After watering seedlings for 5 years, the seeds grew into a tree with a mass of 75 kg. c. The mass of the soil was the same, in which he concluded the mass had come from the water.

  13. 8-2 Photosynthesis d. He didn’t realize that carbon dioxide made up a lot of the mass. e. CO2 is used to make sugars and other carbohydrates.

  14. 8-2 Photosynthesis 2. Priestley’s Experiment a. determined that a waste of plants was oxygen b. Placed a candle and a sprig of mint under a jar and noticed the candle would stay lit longer even under the jar.

  15. 8-2 Photosynthesis 3. Jan Ingenhousz a. The Dutch scientist showed that the effect observed by Priestley occurred when the plant was exposed to light. b. through these three scientists discoveries it was determined that with light, plants transform CO2 and water into carbs, and release oxygen.

  16. 8-2 Photosynthesis B. The photosynthesis Equation 1. 6CO2 + 6H2O –> C6H12O6 + 6O2 carbon dioxide + water –> sugars + oxygen 2. Plants use the sugars to produce complexcarbs such as starches.

  17. Photosynthesis: Reactants and Products Light Energy Chloroplast Sugars + O2 CO2 + H2O

  18. 8-2 Photosynthesis C. Light and Pigments 1. In addition to CO2 and water, photosynthesis requires light and chlorophyll, a molecule in chloroplasts 2. Pigments – light absorbing molecules found in plants

  19. 8-2 Photosynthesis 3. Chlorophyll – plants’ principle pigment a. chlorophyll a , chlorophyll b b. green light is reflected by leaves which is why plants look green c. much of the energy absorbed is transferred directly to electrons.

  20. Chlorophyll Light Absorption Absorption of Light by Chlorophyll a and Chlorophyll b Chlorophyll b Chlorophyll a V B G Y O R

  21. 8-3 The Reactions of Photosynthesis A. Inside a chloroplast 1. Thylakoids – saclike photosynthetic membranes in chloroplasts. a. thylakoids are arranged in stacks known as grana 2. Photosystems – light-collecting units of chloroplast

  22. 8-3 The Reactions of Photosynthesis 3. Two parts – Light-dependent reactions and light independent reactions or Calvin Cycle a. Light-dependent happens in thylakoid membranes b. Calvin Cycle happens in the stroma

  23. H2O CO2 Sugars O2 Photosynthesis: An Overview Chloroplast Chloroplast NADP+ ADP + P Light- Dependent Reactions Calvin Cycle ATP NADPH

  24. 8-3 The Reactions of Photosynthesis B. Electron Carriers 1. sunlight excites electrons in chlorophyll, thus giving the electrons a great deal of energy. 2. high-energy electrons require a special carrier

  25. 8-3 The Reactions of Photosynthesis 3. Carrier molecule accepts a pair of high-energy electrons a. This is known as the electron transport chain

  26. 8-3 The Reactions of Photosynthesis b. NADP+ carrier molecule that accepts and holds 2 high-energy electrons along with a hydrogen ion (H+) i. NADP+ is now converted into NADPH ii. NADPH can now carry the electrons to chemical reaction in the cell

  27. 8-3 The Reactions of Photosynthesis C. Light-Dependent Reactions 1. Requires light 2. Uses light to make ATP and NADPH (energy carriers)

  28. 8-3 The Reactions of Photosynthesis 3. Steps of light-dependent reactions a. Photosystem II - Light absorbed by photosystem II is used to break up water molecules into energized electrons, H+, and oxygen. Oxygen is released as waste and H2 is broken apart and released inside the Thylakoid Membrane.

  29. 8-3 The Reactions of Photosynthesis b. Electron transport chain – electrons from step a move through the chain to photosystem I. H+ is moved from the Stroma into the inner Thylakoid Space.

  30. 8-3 The Reactions of Photosynthesis c. Photosystem I – electrons are energized again. Enzymes use electrons to form NADPH which makes sugar in Calvin Cycle.

  31. 8-3 The Reactions of Photosynthesis d. Hydrogen Ion Movement – Thylakoid membrane fills with H+ making the outside of the membrane negative and the inside positive. This provides energy to make ATP. e. ATP formation – H+ pass, their energy through the ATP Synthase and converts ADP to ATP.

  32. Light-Dependent Reactions Hydrogen Ion Movement Chloroplast Photosystem II ATP synthase Inner Thylakoid Space Thylakoid Membrane Stroma Electron Transport Chain Photosystem I ATP Formation

  33. 8-3 The Reactions of Photosynthesis D. The Calvin Cycle 1. Uses ATP and NADPH (can only hold energy for a few minutes) from the light-dependent reactions to produce high-energy sugars.

  34. 8-3 The Reactions of Photosynthesis 2. Steps of Calvin Cycle a. 6 CO2 molecules combine with 6 five-carbon molecules to produce 12 three-carbon molecules. b. Energy input – ATP and NADPH energies convert 12 three-carbon molecules into higher energy forms.

  35. 8-3 The Reactions of Photosynthesis c. 6-carbon Sugar produced – two 3-carbon molecules are removed to produce sugars, lipids, amino acids and other compounds. d. 5-carbon Molecules Regenerated – the 10 remaining 3-carbon molecules are converted back into six 5-carbon used for next cycle.

  36. Calvin Cycle CO2 Enters the Cycle Energy Input ChloropIast 5-Carbon Molecules Regenerated 6-Carbon Sugar Produced Sugars and other compounds

  37. 8-3 The Reactions of Photosynthesis E. Factors Affecting Photosynthesis 1. Shortage of water 2. Temperature 3. Intensity of light

  38. Light- dependent reactions Calvin cycle Energy from sunlight Thylakoid membranes ATP Stroma NADPH High-energy sugars ATP NADPH O2 Chloroplasts Concept Map Photosynthesis includes takes place in uses use take place in to produce to produce of

More Related