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PhotosynthesisPhotosynthesis A definition: Photosynthesis is the process a plant uses to make food and grow. A definition: Photosynthesis is the process.

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Presentation on theme: "PhotosynthesisPhotosynthesis A definition: Photosynthesis is the process a plant uses to make food and grow. A definition: Photosynthesis is the process."— Presentation transcript:

1 PhotosynthesisPhotosynthesis A definition: Photosynthesis is the process a plant uses to make food and grow. A definition: Photosynthesis is the process a plant uses to make food and grow.

2 Four things are needed for photosynthesis: Travels up from the roots WATER CARBON DIOXIDE Enters the leaf through small holes on the underneath SUNLIGHT Gives the plant energy CHLOROPHYLL The green stuff where the chemical reactions happen

3 The word and chemical equations for photosynthesis: Carbon dioxide + water glucose + oxygen 6CO 2 + 6H 2 0C 6 H 12 O 6 + 6O 2 Sunlight Chlorophyll Sunlight Chlorophyll

4 THE SUN: MAIN SOURCE OF ENERGY FOR LIFE ON EARTH

5 Almost all plants are photosynthetic autotrophs, as are some bacteria and protists Autotrophs generate their own organic matter through photosynthesis Sunlight energy is transformed to energy stored in the form of chemical bonds (a) Mosses, ferns, and flowering plants (b) Kelp (c) Euglena (d) Cyanobacteria THE BASICS OF PHOTOSYNTHESIS

6  Photosynthesis is the process by which autotrophic organisms use light energy to make sugar and oxygen gas from carbon dioxide and water AN OVERVIEW OF PHOTOSYNTHESIS Carbon dioxide WaterGlucoseOxygen gas PHOTOSYNTHESIS

7 The Calvin cycle makes sugar from carbon dioxide ATP generated by the light reactions provides the energy for sugar synthesis The NADPH produced by the light reactions provides the electrons for the reduction of carbon dioxide to glucose Light Chloroplast Light reactions Calvin cycle NADP  ADP + P  The light reactions convert solar energy to chemical energy  Produce ATP & NADPH  The light reactions convert solar energy to chemical energy  Produce ATP & NADPH AN OVERVIEW OF PHOTOSYNTHESIS

8 Light Energy Harvested by Plants & Other Photosynthetic Autotrophs 6 CO H 2 O + light energy → C 6 H 12 O O 2

9 WHY ARE PLANTS GREEN? It has to do with sunlight! Sunlight is a form of electromagnetic energy, which travels in waves.

10 Electromagnetic Spectrum and Visible Light Gamma rays X-raysUV Infrared & Microwaves Radio waves Visible light Wavelength (nm): Distance between two waves

11 Different wavelengths of visible light are seen by the human eye as different colors. WHY ARE PLANTS GREEN? Gamma rays X-raysUVInfrared Micro- waves Radio waves Visible light Wavelength (nm)

12 Sunlight minus absorbed wavelengths or colors equals the apparent color of an object. The feathers of male cardinals are loaded with carotenoid pigments. These pigments absorb some wavelengths of light and reflect others. Reflected light

13  Chloroplasts absorb light energy and convert it to chemical energy Light Reflected light Absorbed light Transmitted light Chloroplast THE COLOR OF LIGHT SEEN IS THE COLOR NOT ABSORBED

14  In most plants, photosynthesis occurs primarily in the leaves, in the chloroplasts  A chloroplast contains:  stroma, a fluid (site of Calvin Cycle)  grana, stacks of thylakoids (site of Light reactions)  The thylakoids contain chlorophyll  Chlorophyll is the green pigment that captures light for photosynthesis  In most plants, photosynthesis occurs primarily in the leaves, in the chloroplasts  A chloroplast contains:  stroma, a fluid (site of Calvin Cycle)  grana, stacks of thylakoids (site of Light reactions)  The thylakoids contain chlorophyll  Chlorophyll is the green pigment that captures light for photosynthesis Photosynthesis occurs in chloroplasts

15  The location and structure of chloroplasts LEAF CROSS SECTION MESOPHYLL CELL LEAF Chloroplast Mesophyll CHLOROPLAST Intermembrane space Outer membrane Inner membrane Thylakoid compartment Thylakoid Stroma Granum StromaGrana

16  Chloroplasts contain several pigments Chloroplast Pigments  Chlorophyll a: absorbs mainly violet and red light the best  Chlorophyll b: absorbs blue and orange light the best  Carotenoids: absorbs blue and green best Figure 7.7

17 Different pigments absorb light differently

18 Paper Chromatography  A laboratory test used to separate and analyze different pigments in a leaf.  Example: https://www.pearsonsuccessnet.com/snpapp/iText/getTeacherHomepa ge.do?newServiceId=6000&newPageId=10100  A laboratory test used to separate and analyze different pigments in a leaf.  Example: https://www.pearsonsuccessnet.com/snpapp/iText/getTeacherHomepa ge.do?newServiceId=6000&newPageId=10100

19 Photosystems: Clusters of pigments in thylakoid membrane  Photosystem I -Traps light energy and transfers the light-excited electrons to an electron transport chain. -Those excited electrons are replaced by splitting a molecule of water, which releases oxygen. -The electron transport chain releases energy, which is used to make ATP  Photosystem II -Produces NADPH by transferring excited electrons and hydrogen ions to NADP+.  Photosystem I -Traps light energy and transfers the light-excited electrons to an electron transport chain. -Those excited electrons are replaced by splitting a molecule of water, which releases oxygen. -The electron transport chain releases energy, which is used to make ATP  Photosystem II -Produces NADPH by transferring excited electrons and hydrogen ions to NADP+.

20 Light Reactions Photosystem I and Photosystem II In the light reactions, electron transport chains generate ATP, NADPH, & O 2  SUMMARY: In the light reactions, electron transport chains generate ATP, NADPH, & O 2  Two connected photosystems collect photons of light and transfer the energy to chlorophyll electrons  The excited electrons are passed from the primary electron acceptor to electron transport chains  The light reactions convert light energy to the chemical energy of ATP and NADPH Watch the following animation: In the light reactions, electron transport chains generate ATP, NADPH, & O 2  SUMMARY: In the light reactions, electron transport chains generate ATP, NADPH, & O 2  Two connected photosystems collect photons of light and transfer the energy to chlorophyll electrons  The excited electrons are passed from the primary electron acceptor to electron transport chains  The light reactions convert light energy to the chemical energy of ATP and NADPH Watch the following animation:

21 Photon Water-splitting photosystem NADPH-producing photosystem ATP mill  Two types of photosystems cooperate in the light reactions Inputs: Water Sunlight energy Outputs: Oxygen ATP NADPH  Two types of photosystems cooperate in the light reactions Inputs: Water Sunlight energy Outputs: Oxygen ATP NADPH

22  The O 2 liberated by photosynthesis is made from the oxygen in water (H + and e - ) Plants produce O 2 gas by splitting H 2 O

23 2 H  + 1 / 2 Water-splitting photosystem Reaction- center chlorophyll Light Primary electron acceptor Energy to make Electron transport chain Primary electron acceptor Primary electron acceptor NADPH-producing photosystem Light NADP  How the Light Reactions Generate ATP and NADPH

24  The production of ATP in photosynthesis Thylakoid compartment (high H + ) Thylakoid membrane Stroma (low H + ) Light Antenna molecules Light ELECTRON TRANSPORT CHAIN PHOTOSYSTEM IIPHOTOSYSTEM IATP SYNTHASE

25  A Photosynthesis Road Map Chloroplast Light Stack of thylakoids ADP + P NADP  Stroma Light reactions Calvin cycle Sugar used for  Cellular respiration  Cellulose  Starch  Other organic compounds

26 Calvin Cycle Called a cycle because the starting material, RuBP, is regenerated. Uses carbon from carbon dioxide, the energy from ATP, and high energy electrons and hydrogen ions from NADPH to make a small sugar named G3P. The plant uses G3P to make glucose and other organic molecules. Overall input: CO 2, ATP, NADPH Overall output: Glucose Called a cycle because the starting material, RuBP, is regenerated. Uses carbon from carbon dioxide, the energy from ATP, and high energy electrons and hydrogen ions from NADPH to make a small sugar named G3P. The plant uses G3P to make glucose and other organic molecules. Overall input: CO 2, ATP, NADPH Overall output: Glucose

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28 Calvin Cycle Watch the following animation: Watch the following animation:

29 Review: Photosynthesis uses light energy to make food molecules Light Chloroplast Photosystem II Electron transport chains Photosystem I CALVIN CYCLE Stroma Electrons LIGHT REACTIONSCALVIN CYCLE Cellular respiration Cellulose Starch Other organic compounds  Light reactions use water and produce oxygen.  The Calvin Cycle uses ATP and NADPH created in the the light reactions to convert carbon dioxide to glucose.  Light reactions use water and produce oxygen.  The Calvin Cycle uses ATP and NADPH created in the the light reactions to convert carbon dioxide to glucose.

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31  Animation is of the Calvin Cycle Note what happens to the carbon dioxide and what the end product is. Animation is of the Calvin Cycle  Second animation of the Calvin Cycle is very clear and even does the molecular bookkeeping for you. Second animation of the Calvin Cycle  Animation is of the Calvin Cycle Note what happens to the carbon dioxide and what the end product is. Animation is of the Calvin Cycle  Second animation of the Calvin Cycle is very clear and even does the molecular bookkeeping for you. Second animation of the Calvin Cycle


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