1. Chapter 8 Photosynthesis

2. What is this?

3. 8.1 Energy and Life  Nearly every activity in modern society depends on energy.  What kind of energy is used for a car to move?  Chemical  What kind of energy is used for appliances?  Electrical

4.  Every activity you do, requires energy.  Humans also need to eat for energy.  Walking burns 158 kcal per hour.  Swimming burns 525 kcal per hour.  Sleeping and sitting burns 28 kcal per hour.

5.  Adenosine triphosphate (ATP): Cells use to store and release energy.  Consists of three parts  1. Adenine  2. 5 carbon sugar called ribose  3. Tri= Three phosphate groups.

6.  We also have Adenosine diphosphate (ADP).  It consists of…  1. Adenine  2. 5 carbon sugar called ribose  3. di=2 phosphate groups.

7. Releasing Energy  Chemical bonds use energy to hold together different molecules.  When ATP is transformed into ADP, a chemical bond is broken, and energy is released.

8. Releasing Energy

9. Heterotrophs and Autotrophs  How do animals get their energy?  Obtain food by consuming other living things.  We are heterotrophs.  Autotrophs:  Organisms that make their own food.

10. PRODUCERS - PHOTOAUTOTROPHS

11. CONSUMERS - HETEROTROPHS

12.  What process do plants use to get energy?  Photosynthesis:  Autotrophs use the energy from sunlight to produce a high energy carbohydrates sugars and starches that can be used as food.

13. 8.2 Photosynthesis: An Overview If chlorophyll is green then how are leaves orange, yellow and red? They have different kinds of pigments. Pigment: Light absorbing molecules.

14. Identifying Pigments  Chloroplast is made up of chlorophyll a which gives the plant its green color main use for photosynthesis.  Chlorophyll b which reflects yellow-green light.  Carotenoids which reflects yellow-orange light.

15. When you shine light at a leaf.. Is the green light being absorbed, transmitted, or reflected? Reflected. The chloroplast absorbs the blue-violet light and red-orange light very well but the green light reflects.

16. Who is this?  What kind of radiation turned him into the Hulk?

17.  Very short wavelengths (high energy) are called gamma rays.  Very long wavelengths (low energy) are called radio waves.

18. Chloroplast Structure  Chloroplast:  Cellular organelle where photosynthesis takes place. Contains chlorophyll that gives these organelles a green color.

19.  Electromagnetic spectrum:  Range of types of electromagnetic energy.

20. Chloroplast Structure  Thylakoids:  Are arranged in sacs called grana. They organize and complex series of chemical reactions that make up the process of photosynthesis.

21. Chloroplast Structure  Chloroplast has an inner and outer membrane. Within the inner membrane is the thick fluid stroma.

22. High Energy Electrons  The high energy electrons produced by chlorophyll are highly reactive and require a special “carrier.”  Think of a hot potato. You wouldn't pick up a hot potato with your bare hands. You would use an oven mitt.  Much like an oven mitt, you would use a carrier to transport high energy electrons.

23.  NADP + Nicotinamide adenine dinucleotide phosphate:  Accepts and holds high energy electrons.  Along with a Hydrogen ion (H), NADP + turns into NADPH.  NADPH can then carry the high energy electrons that were produced elsewhere in the cell.  These help build a variety of molecules like carbs and glucose.

24. Overview of Photosynthesis  What do plants give animals in order for them to survive?  What are the products of photosynthesis?

25. Photosynthesis has 2 reactions  1. Light-Dependent Reaction:  Requires the direct involvement of light and light absorbing pigments.  2. Light-Independent Reaction:  Does not involve light and produces sugar.

27. 8.3 The Process of Photosynthesis  The first reaction is the light-dependent reaction.  Takes place in the thylakoids.

28. Light-Dependent Reactions  Photosynthesis involves two sets of reactions.  The first set of reactions is known as the light-dependent reactions because they require the direct involvement of light and light- absorbing pigments.

29. A - Photosystem II Photosynthesis begins when chlorophyll absorbs light energy from the sun. The light energy causes electrons in chlorophyll to become excited, increasing their energy level. Before electrons can leave the chlorophyll, they must be replaced by electrons from the splitting of water molecules. The splitting of water molecules releases electrons and protons into the thylakoid and produces oxygen gas. Light-dependent Reactions of Photosynthesis H 2 O  2 H + +O+2 e —

30. B. Electron Transport Chain (ETC) The excited electrons are then passed through the thylakoid membrane from one carrier molecule to another. Light-dependent Reactions of Photosynthesis

31. Light-Dependent Reactions  The light-dependent reactions use energy from sunlight to produce ATP and NADPH.  These reactions take place within the thylakoid membranes of the chloroplast.

32. Light-Dependent Reactions  Water is required as a source of electrons and hydrogen ions. Oxygen is released as a byproduct.

33. Light Independent Reactions AKA The Calvin Cycle

34. Light-Independent Reactions  Plants absorb carbon dioxide from the atmosphere and complete the process of photosynthesis by producing sugars and other carbohydrates.  During light-independent reactions, ATP and NADPH molecules produced in the light- dependent reactions are used to produce high- energy sugars from carbon dioxide.

35. Light-Independent Reactions  No light is required to power the light- independent reactions.  The light-independent reactions take place outside the thylakoids, in the stroma.

36. Factors Affecting Photosynthesis  What are some factors that affect photosynthesis?  Temperature  Light Intensity  Availability of water

37. Severe Environments  C4 Plants – photosynthesize under intense light and high temperature. They have a 4-carbon sugar in their photosynthetic cycle (not Calvin Cycle. Eg. Corn, sugar cane  CAM plants – live in extremely hot and dry climates. Most cacti, succulents, pineapple are CAM plants. Evolved to capture CO2 at night.

38. Relationship between the Light-Dependent and Light-Independent RXNs Light-dependent reactions Light-independent reactions (Calvin Cycle) Reactants (IN) Products (OUT) Reactants (IN) Products (OUT) Light H 2 O NADP + + H + ADP + P O 2 NADPH ATP C 6 H 12 O 6 NADP + + H + ADP + P CO 2 NADPH ATP

39. Summary Questions  Where do the light-dependent reactions occur in the chloroplast?  Thylakoids  What are the products of the light- dependent reactions?  NADPH, ATP, and oxygen gas

40. Summary Questions  Where does the Calvin cycle (light- independent reaction) take place in the chloroplast?  Stroma