Chapter 7 Photosynthesis: Using Light to Make Food

Chapter 7 Photosynthesis: Using Light to Make Food PowerPoint Lectures Campbell Biology: Concepts & Connections, Eighth Edition REECE TAYLOR SIMON DICKEY HOGAN Lecture by Edward J. Zalisko

Figure 7.0-2 Chapter 7 Objectives: You will Describe where photosynthesis occurs Illustrate how Photosynthesis Converts Solar Energy to Chemical Energy Explain how chemical energy is used to reduce CO 2 to Sugar Predict global photosynthetic patterns

AN INTRODUCTION TO PHOTOSYNTHESIS

Figure 7.1 Photoautotroph diversity

Figure 7.2-1 Leaf Cross Section Mesophyll Leaf Vein Mesophyll Cell CO 2 O 2 Stoma Chloroplast

Figure 7.2-0 Leaf Cross Section Mesophyll Leaf Vein Mesophyll Cell CO 2 O 2 Stoma Chloroplast Inner and outer membranes Granum Stroma Thylakoid Thylakoid space

Figure 7.2-2 Mesophyll Cell Chloroplast Inner and outer membranes Granum Stroma Thylakoid Thylakoid space

7.3 Scientists traced the process of photosynthesis using isotopes Read page 110 and be prepared to discuss

Figure 7.3 Oxygen bubbles on the leaves of an aquatic plant

7.3 Scientists traced the process of photosynthesis using isotopes Experiment 1: 6 CO 2 12 H 2 O C 6 H 12 O 6 6 H 2 O 6 O 2 Experiment 2: 6 CO 2 12 H 2 O C 6 H 12 O 6 6 H 2 O 6 O 2

Figure 7.4a Photosynthesis (uses light energy) Becomes reduced 6 CO 2 + 6 H 2 O C 6 H 12 O 6 + 6 O 2 Becomes oxidized

Figure 7.4b Cellular respiration (releases chemical energy) Becomes oxidized C 6 H 12 O 6 + 6 O 2 6 CO 2 + 6 H 2 O Becomes reduced

OIL RIG Oxidation Is Loss Reduction Is Gain

Figure 7.5-1 H 2 O Light NADP + ADP + P Light Reactions (in thylakoids) Chloroplast

Figure 7.5-2 H 2 O Light NADP + ADP + P Light Reactions (in thylakoids) ATP NADPH Chloroplast O 2

Figure 7.5-3 H 2 O CO 2 Light NADP + ADP + P Light Reactions (in thylakoids) ATP Calvin Cycle (in stroma) NADPH Chloroplast O 2 Sugar

You should now be able to 1. Define autotrophs, heterotrophs, producers, and photoautotrophs. 2. Describe the structure of chloroplasts and their location in a leaf. 3. Explain how plants produce oxygen. 4. Describe the role of redox reactions in photosynthesis and cellular respiration. 5. Compare the reactants and products of the light reactions and the Calvin cycle.

THE LIGHT REACTIONS: CONVERTING SOLAR ENERGY TO CHEMICAL ENERGY

Figure 7.0-2 Chapter 7 Objectives: You will Describe where photosynthesis occurs Illustrate how Photosynthesis Converts Solar Energy to Chemical Energy Explain how chemical energy is used to reduce CO 2 to Sugar Predict global photosynthetic patterns

Photosynthesis

Underside of leaf

Pores on surface of leaf Carbon dioxide (CO 2 ) Photosynthesis requires carbon dioxide, which diffuses into the leaf through small pores,

Photosynthetic cells inside leaf Carbon dioxide (CO 2 )

Plant cell wall Carbon dioxide (CO 2 )

Carbon dioxide (CO 2 ) Chloroplast Inside the cell, carbon dioxide diffuses into the chloroplasts, where photosynthesis takes place.

Light energy Carbon dioxide (CO 2 ) Sugar Water (H 2 O) Oxygen (O 2 ) 6 CO 2 + 6 H 2 O + Light --> Sugar + 6 O 2

Figure 7.6a The electromagnetic spectrum and the wavelengths of visible light Shorter wavelength Higher energy Longer wavelength Lower energy 10 5 nm 10 3 nm 1 nm 10 3 nm 10 6 nm 1 m 10 3 m Gamma rays X-rays UV Infrared Microwaves Radio waves Visible light 380 400 500 600 700 750 Wavelength (nm)

Estimated Absorption (%) 8-2 Photosynthesis: An Overview Light and Pigments Chlorophyll absorbs blue-violet and red regions of the visible spectrum. 100 80 60 40 Chlorophyll b Chlorophyll a 20 0 400 450 Wavelength 500 550 600 (nm) 650 700 750 Wavelength (nm) Slide 29 of 28 Copyright Pearson Prentice Hall

p. 163

Animation: Light and Pigments

Figure 7.6b-0 Light Reflected light Chloroplast Thylakoid Absorbed light Transmitted light

Figure 7.6b-1 Light Reflected light Chloroplast Thylakoid Absorbed light Transmitted light

Figure 7.7a-0 Excited state Photon of light Heat Photon (fluorescence) Ground state Chlorophyll molecule A solution of chlorophyll glowing red when illuminated (left); diagram of an isolated, light-excited chlorophyll molecule that releases a photon of red light (right)

Chlorophyll Molecule http://www.sciencechannel.com/tvshows/what-on-earth/what-on-earthvideos/strange-force-sweeps-over-northamerica/

Figure 7.7b Thylakoid membrane Photosystem Light STROMA Light-harvesting complexes Reaction-center complex Primary electron acceptor THYLAKOID SPACE Transfer of energy Pair of chlorophyll a molecules Pigment molecules

Figure 7.8 ATP NADPH Electron transport chain ramp Photosystem II Photosystem I

8-3 The Reactions of Photosynthesis PS II is energized by light Light-Dependent Reactions Photosystem II Slide 38 of 51 Copyright Pearson Prentice Hall

8-3 The Reactions of Photosynthesis And loses an electron. Light-Dependent Reactions Photosystem II Electron carriers Slide 39 of 51 Copyright Pearson Prentice Hall

8-3 The Reactions of Photosynthesis Light-Dependent Reactions Water is broken to replace the electron lost from PSII Photosystem II 2H 2 O Slide 40 of 51 Copyright Pearson Prentice Hall

8-3 The Reactions of Photosynthesis Oxygen are hydrogen are released Light-Dependent Reactions Photosystem II 2H 2 O + O 2 Slide 41 of 51 Copyright Pearson Prentice Hall

8-3 The Reactions of Photosynthesis Light-Dependent Reactions Energy from the electrons is used to transport more H + ions into the inner thylakoid space. Photosystem II 2H 2 O + O 2 Slide 42 of 51 Copyright Pearson Prentice Hall

8-3 The Reactions of Photosynthesis Light re-energizes the electrons in PSI. Light-Dependent Reactions 2H 2 O + O 2 Photosystem I Slide 43 of 51 Copyright Pearson Prentice Hall

8-3 The Reactions of Photosynthesis Light-Dependent Reactions NADP + picks up electrons and H + ions and becomes NADPH. 2H 2 O + O 2 NADP + NADPH Slide 44 of 51 Copyright Pearson Prentice Hall

8-3 The Reactions of Photosynthesis Light-Dependent Reactions Soon, the thylakoid space fills up with hydrogen ions makes it positively charged. 2H 2 O + O 2 NADP + NADPH Slide 45 of 51 Copyright Pearson Prentice Hall

8-3 The Reactions of Photosynthesis Light-Dependent Reactions An enzyme called ATP synthase allows H + ions to pass through it. ATP synthase 2H 2 O + O 2 NADP + NADPH Slide 46 of 51 Copyright Pearson Prentice Hall

8-3 The Reactions of Photosynthesis Light-Dependent Reactions The charge difference creates enough energy to add a P to ADP making ATP. ATP synthase 2H 2 O + O 2 NADP + ADP NADPH Slide 47 of 51 Copyright Pearson Prentice Hall

Figure 7.9-0 Thylakoid sac Light Photosystem II H + Electron Light transport chain Photosystem H + I NADP + + H + NADPH Chloroplast H 2 O 1 2 O 2 + 2 H + H + H + H + H + H + THYLAKOID SPACE H + H + H + H + H + H + H + H + H + H + H + H + H + H + To Calvin Cycle Thylakoid membrane ATP synthase H + STROMA H + H + H + ADP + P ATP H +

Figure 7.9-1 Light Photosystem II Primary electron acceptor Pigment molecules Reaction center pair of chlorophyll a molecules H 2 O 1 2 O 2 + 2 H +

Figure 7.9-2 H + H + H + Light Photosystem II H + Electron transport chain H + H 2 O 1 2 O 2 + 2 H + H +

Figure 7.9-3 Light Photosystem II H + Electron Light transport chain Photosystem I H + Primary electron acceptor Pigment molecules Reaction center pair of chlorophyll a molecules H + H + H + H 2 O 1 2 O 2 + 2 H + H + H + H +

Figure 7.9-4 Light Photosystem II H + Electron Light transport chain Photosystem I H + NADP + H + NADPH H 2 O 1 2 O 2 + 2 H + H + H + H + H + H + H + H + H + H + H + H + To Calvin Cycle

Figure 7.9-5 Light Photosystem II H + Electron Light transport chain Photosystem I H + NADP + H + NADPH H 2 O 1 2 O 2 + 2 H + H + H + H + H + THYLAKOID SPACE H + H + H + H + H + H + H + H + H + H + H + H + H + H + H+ To Calvin Cycle Thylakoid membrane ATP synthase H + H + STROMA H + H + ADP + P ATP H +

Stroma Chloroplast membranes Thylakoids

Surface of thylakoid with photosynthetic complexes ATP Electron carrier (NADPH) Chemical energy from the light reactions

Stroma Electron Transport Chain Photosystem Thylakoid membrane Interior of thylakoid Photosystem

Hydrogen ions Electrons Beginning of electron transport chain Water Photosystem Electron from water Oxygen Hydrogen ions The photosystem on the left absorbs light energy, exciting electrons that enter the electron transport chain. Electrons are replaced with electrons stripped from water, creating oxygen as a by-product.

Electron transport chain Electrons Hydrogen ions Interior of thylakoid The energized electrons flow down the electron transport chain, releasing energy that is used to pump hydrogen ions (the blue balls) into the thylakoid.

Electron Photosystem In the photosystem on the right, light energy excites electrons, and this time...

NADPH (electron carrier) the electrons are captured by an electron carrier molecule NADPH.

ATP ATP synthase High concentration of hydrogen ions inside thylakoid

Energy products of the light reactions NADPH ATP The light reactions in the thylakoid have produced two energy products--atp and NADPH--that will now power the production of sugar in the Calvin cycle.

You should now be able to 6. Describe the properties and functions of the different photosynthetic pigments. 7. Explain how photosystems capture solar energy. 8. Explain how the electron transport chain and chemiosmosis generate ATP, NADPH, and oxygen in the light reactions. 9. Compare photophosphorylation and oxidative phosphorylation.

THE CALVIN CYCLE: REDUCING CO 2 TO SUGAR

Figure 7.0-2 Chapter 7 Objectives: You will Describe where photosynthesis occurs Illustrate how Photosynthesis Converts Solar Energy to Chemical Energy Explain how chemical energy is used to reduce CO 2 to Sugar Predict global photosynthetic patterns

Figure 7.10-0 Light H 2 O CO 2 NADP + ADP Light Reactions + P ATP NADPH Calvin Cycle Input 3 CO 2 Step 1 Carbon fixation Chloroplast O 2 Sugar Rubisco 3 P RuBP P 6 3-PGA P 6 ATP Step 4 Regeneration of RuBP 3 ADP 3 ATP P CALVIN CYCLE 6 ADP + P 6 NADPH 5 G3P Step 3 Release of one molecule of G3P P 6 G3P P Step 2 Reduction 6 NADP + 1 G3P Output P Glucose and other compounds

Melvin Calvin

Figure 7.10-3-1 Input 3 CO 2 Step 1 Carbon fixation Rubisco 3 P RuBP P 6 3-PGA P CALVIN CYCLE

Figure 7.10-3-2 Input 3 CO 2 Step 1 Carbon fixation Rubisco 3 P RuBP P 6 3-PGA P 6 ATP CALVIN CYCLE 6 ADP + P 6 NADPH 6 P G3P Step 2 Reduction 6 NADP +

Figure 7.10-3-3 Input 3 CO 2 Step 1 Carbon fixation Rubisco 3 P RuBP P 6 3-PGA P 6 ATP CALVIN CYCLE 6 ADP + P 6 NADPH 5 G3P Step 3 Release of one molecule of G3P P 6 P G3P Step 2 Reduction 6 NADP + 1 G3P Output P Glucose and other compounds

Figure 7.10-3-4 Input 3 CO 2 Step 1 Carbon fixation Rubisco 3 P RuBP P 6 3-PGA P 6 ATP Step 4 Regeneration of RuBP 3 ADP 3 ATP CALVIN CYCLE 6 ADP + P 6 NADPH 5 G3P Step 3 Release of one molecule of G3P P 6 P G3P Step 2 Reduction 6 NADP + 1 G3P Output P Glucose and other compounds

Carbon dioxide RuBP The Calvin cycle takes place outside the thylakoids in the stroma the thick fluid of the chloroplast. At the beginning of the cycle, carbon dioxide molecules combine with molecules called RuBP.

NADPH The resulting molecules go through a series of reactions powered by ATP and NADPH from the light reactions.

G3P Sugar molecules known as G3Ps are produced.

RuBPs G3P Most of the G3Ps are rearranged back into RuBPs that will begin the Calvin cycle again. But the important product of photosynthesis is the remaining G3P sugar.

Glucose Starch G3P Some G3Ps are used to build glucose, which can combine into starch or cellulose.

Chloroplast Still other G3Ps form sucrose. Sucrose

And some of the sugar is broken down by cellular respiration using oxygen in the plant s own mitochondria, generating ATPs that can power other work of the plant. ATP Cellular respiration in mitochondrion

Carbon dioxide Pore in leaf Oxygen Excess oxygen diffuses out of the leaf through the pores, while more carbon dioxide enters.

7.11 EVOLUTION CONNECTION: Other methods of carbon fixation have evolved in hot, dry climates Read page 117 and be prepared to discuss

7.11 EVOLUTION CONNECTION: Other methods of carbon fixation have evolved in hot, dry climates Indian Rice (Achnathrum hymenoides) Grass is C 3 Galletta Grass (Pleuraphis jamesii) is C 4

Figure 7.11-0 Mesophyll cell CO 2 Night CO 2 4-C compound 4-C compound Bundlesheath cell CO 2 CO 2 Calvin Cycle Calvin Cycle Sugar C 4 plant Day Sugar CAM plant Sugarcane Pineapple

You should now be able to 11. Describe the reactants and products of the Calvin cycle. 12. Compare the mechanisms that C 3, C 4, and CAM plants use to obtain and use carbon dioxide. 13. Review the overall process of the light reactions and the Calvin cycle, noting the products, reactants, and locations of every major step.

THE GLOBAL SIGNIFICANCE OF PHOTOSYNTHESIS

Figure 7.0-2 Chapter 7 Objectives: You will Describe where photosynthesis occurs Illustrate how Photosynthesis Converts Solar Energy to Chemical Energy Explain how chemical energy is used to reduce CO 2 to Sugar Predict global photosynthetic patterns

Figure 7.12 A summary of photosynthesis Light H 2 O Chloroplast CO 2 NADP + Thylakoids Light Reactions Photosystem II Electron transport chain Photosystem I ADP + P ATP RuBP Calvin Cycle 3-PGA (in stroma) Stroma O 2 NADPH G3P Sugars Cellular respiration Cellulose Starch Other organic compounds

7.13 SCIENTIFIC THINKING: Rising atmospheric levels of carbon dioxide and global climate change will affect plants in various ways Read page 119

7.13 SCIENTIFIC THINKING: Rising atmospheric levels of carbon dioxide and global climate change will affect plants in various ways The carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. The use of ethanol as an alternative is complicated by the typical reliance upon fossil fuels for ethanol production.

Figure 7.13a Large-scale experiment in the Duke University Experimental Forest on the effects of elevated CO 2 concentration

Figure 7.0-1 Poison ivy in the elevated CO 2 plots

Figure 7.13b Mean plant dry biomass (g) 10 9 8 7 6 5 4 3 2 1 0 1999 2000 2001 2002 2003 2004 Year Key Control plots Elevated CO 2 plots Source: Adaptation of Figure 1A from Biomass and Toxicity Responses of Poison Ivy (Toxicodendron Radicans) to Elevated Atmospheric CO 2 by Jacqueline E. Mohan, et al., from PNAS, June 2006, Volume 103(24). Copyright 2006 by National Academy of Sciences. Reprinted with permission.

7.14 Scientific research and international treaties have helped slow the depletion of Earth s ozone layer Read page 120

7.14 Scientific research and international treaties have helped slow the depletion of Earth s ozone layer The ozone is in the stratosphere Greenhouse gases are in the troposphere They are not chemically linked in any way

Figure 7.14a Southern tip of South America Antarctica September 2012

Figure 7.14b Susan Solomon at her cold research site

https://svs.gsfc.nasa.gov/11781

You should now be able to 11. Describe the greenhouse effect. 12. Explain how the ozone layer forms, how human activities have damaged it, and the consequences of the destruction of the ozone layer.

Algae Key http://cfb.unh.edu/phycokey/choices/ Chlorophyceae/colonies/colonies_not _flagellated/scenedesmus/scene desmus_key.html

Chapter 7 Photosynthesis: Using Light to Make Food Clicker Questions for Campbell Biology: Concepts & Connections, Eighth Edition REECE TAYLOR SIMON DICKEY HOGAN Updated by Shannon Datwyler

Figure 7.UN03 (a) to chemical energy Photosynthesis converts includes both (b) (c) in which in which H 2 O is split light-excited electrons of chlorophyll CO 2 is fixed to RuBP and and then (d) are passed down Reduce NADP + to using 3-PGA is reduced (e) (f) to produce producing chemiosmosis by (g) (h)

Figure 7.UN04 Mitochondrion Intermembrane space H + c. Chloroplast Membrane Matrix d. a. b. e.

Concept Check This is the summary equation for the process of photosynthesis. This reaction a) is endergonic. b) is exergonic. c) has an equal amount of energy in the reactants and the products. d) both b and c.

Answer This is the summary equation for the process of photosynthesis. This reaction a) is endergonic. b) is exergonic. c) has an equal amount of energy in the reactants and the products. d) both b and c.

Concept Check Both cellular respiration and photosynthesis rely on electron transport chains embedded in membranes to produce ATP molecules. Which of the following correctly describes the difference between the two types of electron transport chains? a) In cellular respiration, the electron source is water and the final electron destination is oxygen. b) In cellular respiration, the electron source is the hydrogens in energy rich food and the final electron destination is oxygen. c) Both a and b.

Answer Both cellular respiration and photosynthesis rely on electron transport chains embedded in membranes to produce ATP molecules. Which of the following correctly describes the difference between the two types of electron transport chains? a) In cellular respiration, the electron source is water and the final electron destination is oxygen. b) In cellular respiration, the electron source is the hydrogens in energy rich food and the final electron destination is oxygen. c) In photosynthesis the electron source is water and the final destination is oxygen. d) Both b and c.

Concept Check When a photon of the correct energy is absorbed by a photosystem, an electron is energized and transferred to a primary electron acceptor. This creates an electron hole. How is the missing electron replaced? a) Electrons removed from glucose replace the missing electrons. b) Electrons from hydrogen made available by splitting water replace the missing electrons. c) The replacement electrons come from NADPH. d) The electrons come from ATP.

Answer When a photon of the correct energy is absorbed by a photosystem, an electron is energized and transferred to a primary electron acceptor. This creates an electron hole. How is the missing electron replaced? a) Electrons removed from glucose replace the missing electrons. b) Electrons from hydrogen made available by splitting water replace the missing electrons. c) The replacement electrons come from NADPH. d) The electrons come from ATP.

Concept Check Imagine that you have planted bean seedlings (C 3 ) and corn seedlings (C 4 ) in an artificial soil and sealed them in an aquarium. The aquarium has plenty of light, nutrients, and water but a given volume of air. Based on your knowledge of photorespiration, which of the following are most likely? a) Both kinds of plants should do equally well. b) As the plants photosynthesize the carbon dioxide levels will fall giving the C 3 plants the advantage. c) As the plants photosynthesize the carbon dioxide levels will fall giving the C 4 plants the advantage. d) The results are unpredictable.

Answer Imagine that you have planted bean seedlings (C 3 ) and corn seedlings (C 4 ) in an artificial soil and sealed them in an aquarium. The aquarium has plenty of light, nutrients, and water but a given volume of air. Based on your knowledge of photorespiration, which of the following are most likely? a) Both kinds of plants should do equally well. b) As the plants photosynthesize the carbon dioxide levels will fall giving the C 3 plants the advantage. c) As the plants photosynthesize the carbon dioxide levels will fall giving the C 4 plants the advantage. d) The results are unpredictable

Biology and Society The increases in atmospheric carbon dioxide and global surface temperature are real, but a direct correlation between the two is difficult to prove. Do you think we need evidence of a direct correlation between atmospheric carbon dioxide and global surface temperature before taking aggressive action? Strongly A B C D E Strongly Disagree Agree

Biology and Society The increases in atmospheric carbon dioxide and global surface temperature are real, but a direct correlation between the two is difficult to prove. Do you think we need to start curbing carbon dioxide emissions immediately? Strongly A B C D E Strongly Disagree Agree

Jeopardy!!!!!!!! Chapters 1-7