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Picture Guide to Chapter 8 Photosynthesis. 8-1 Energy and Life.

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Presentation on theme: "Picture Guide to Chapter 8 Photosynthesis. 8-1 Energy and Life."— Presentation transcript:

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

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11 ATP Formation - Using Biomechanical Energy Active Transport Movement of organelles throughout cell Synthesis of proteins and nucleic acids Produce light –Blink of firefly caused by an enzyme powered by ATP

12 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

13 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

14 Photosynthesis

15 The Photosynthesis Equation CO 2 +H2OH2O+C 6 H 12 O 6 O2O2 light (Carbon Dioxide)(Water)(Sun)(Glucose)(Oxygen)

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

17 Absorption of Light by Chlorophyll a and Chlorophyll b Absorption of Light by Chlorophyll a and Chlorophyll b VBGYOR Chlorophyll b Chlorophyll a

18 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

19 8-3 The Reactions of Photosynthesis

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21 Thylakoids Sac-like photosynthetic membranes arranged in stacks

22 Grana Stacks of thylakoids

23 Stroma The region outside the thylakoid

24 Scientists describe the reactions of photosynthesis in two parts 1.Light – dependent reactions (takes place in the thylakoid membranes) 2.Light – independent reactions (takes place in stroma)

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26 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+

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

29 Light Dependent Reactions Uses energy from light to produce 1.Oxygen gas 2.ATP 3.NADPH

30 Fig. 8-10

31 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

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

33 Fig 8.11

34 Factors Affecting Photosynthesis Not enough water Temperature Light intensity


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