This document provides an overview of photosynthesis. It explains that plants get their energy from sunlight through the process of photosynthesis, where carbon dioxide, water, and sunlight are converted into glucose and oxygen. Chlorophyll is the pigment in plants that absorbs light energy. The reactions of photosynthesis are divided into light-dependent reactions, which take place in thylakoid membranes and produce ATP and NADPH, and light-independent reactions called the Calvin cycle, which use these products to produce sugars. Factors like water availability, temperature, and light intensity can affect photosynthesis.

1. Picture Guide to Chapter 8 Photosynthesis

2. 8-1 Energy and Life

3. Objectives Explain where plants get the energy they need to produce food Describe the role of ATP in cellular activities

4. Q: Where does energy come from? A: Our food, but originally the energy in food comes from the sun

5. Autotrophs Make their own food

6. Heterotrophs Cannot make their own food

7. Chemical Energy and ATP The principal chemical compounds that cells use to store and release energy is called ATP adenosine triphosphate

8. Storing Energy ATP stores energy in the third phosphate ATP is like a fully charged battery

9. Releasing Energy Q: How is the energy in ATP released? A: Break bond between the second and 3 rd phosphates ADP 2

12. Using Biomechanical Energy Active Transport Movement of organelles throughout cell Sythesis of proteins and nucleic acids Produce light Blink of firefly caused by an enzyme powered by ATP

13. ATP Availability Most cells only have enough ATP for a few seconds of activity Why? Not good at storing energy over the long term Glucose stores 90 times the chemical energy of ATP Cells generate ATP from ADP as needed by using the energy in foods like glucose

14. 8-2 Photosynthesis: An Overview

15. Photosynthesis The process in which plants use the energy of sunlight to convert water and carbon dioxide into high energy carbohydrates – sugars and starches – and oxygen as a waste product

16. Photosynthesis

17. The Photosynthesis Equation CO 2 + H 2 O + C 6 H 12 O 6 O 2 light (Carbon Dioxide) (Water) (Sun) (Glucose) (Oxygen)

19. Chlorophyll The plants principal pigment, absorbs light energy in the blue-violet and red spectrum of visible light

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

21. Because light is a form of energy… Anything that absorbs light also absorbs the energy from that light When chlorophyll absorbs light, much of the energy is transferred to electrons in the chlorophyll molecule, raising the energy level of these electrons These high-energy electrons make photosynthesis work

22. 8-3 The Reactions of Photosynthesis

24. Thylakoids Sac-like photosynthetic membranes arranged in stacks

25. Grana Stacks of thylakoids

26. Stroma The region outside the thylakoid

27. Scientists describe the reactions of photosynthesis in two parts Light – dependent reactions (takes place in the thylakoid membranes) Light – independent reactions (takes place in stroma)

29. Carrier Molecule Compound that can accept a pair of high energy electrons and transfer them along with most of their energy to another molecule Ex.) NADP+

31. Q: What does this do? NADP+ NADPH A: this traps sunlight in chemical form

32. Light Dependent Reactions Uses energy from light to produce Oxygen gas ATP NADPH

36. The Calvin Cycle The ATP and NADPH formed by the light-dependent reactions contain an abundance of chemical energy, but they are not stable enough to store that energy for more than a few minutes. The Calvin cycle uses ATP and NADPH from light – dependent reactions to produce high energy sugars

37. The Calvin Cycle These reactions don’t require light, therefore these reactions are called Light – independent reactions

40. Factors Affecting Photosynthesis Not enough water Temperature Light intensity

41. THE END