MONDAY BELLRINGER 1

HISTORY OF PHOTOSYNTHESIS & PLANT PIGMENTS 2

INVESTIGATING PHOTOSYNTHESIS Many Scientists Have Contributed To Understanding Photosynthesis Many Scientists Have Contributed To Understanding Photosynthesis Early Research Focused On The Overall Process Early Research Focused On The Overall Process Later Researchers Investigated The Detailed Chemical Pathways Later Researchers Investigated The Detailed Chemical Pathways 3

VAN HELMONT’S EXPERIMENT 1643 Planted a seed into A pre- measured amount of soil and watered for 5 years Planted a seed into A pre- measured amount of soil and watered for 5 years Weighed Plant & Soil. Plant Was 75 kg, Soil The Same. Weighed Plant & Soil. Plant Was 75 kg, Soil The Same. Concluded Mass Came From Water Concluded Mass Came From Water 4

PRIESTLEY’S EXPERIMENT 1771 Burned Candle In Bell Jar Until It Went Out. Burned Candle In Bell Jar Until It Went Out. Placed Sprig Of Mint In Bell Jar For A Few Days. Placed Sprig Of Mint In Bell Jar For A Few Days. Candle Could Be Relit And Burn. Candle Could Be Relit And Burn. Concluded Plants Released Substance (O 2 ) Necessary For burning. Concluded Plants Released Substance (O 2 ) Necessary For burning. 5

INGENHOUSZ’S EXPERIMENT Repeated Priestly experiment with & without sunlight

RESULTS OF INGENHOUSZ’S EXPERIMENT Showed That Priestley’s Results Only Occurred In The Presence Of Sunlight. Showed That Priestley’s Results Only Occurred In The Presence Of Sunlight. Light Was Necessary For Plants To Produce The “Burning Gas” or oxygen Light Was Necessary For Plants To Produce The “Burning Gas” or oxygen 7

JULIUS ROBERT MAYER 1845 Proposed That Plants can Convert Light Energy Into Chemical Energy Proposed That Plants can Convert Light Energy Into Chemical Energy 8

SAMUEL RUBEN & MARTIN KAMEN 1941 Used Isotopes To Determine That The Oxygen Liberated In Photosynthesis Comes From Water 9 KAMEN RUBIN

MELVIN CALVIN 1948 First to trace the path that carbon (CO 2 ) takes in forming Glucose First to trace the path that carbon (CO 2 ) takes in forming Glucose Does NOT require sunlight Does NOT require sunlight Called the Calvin Cycle or Light Independent Reaction Called the Calvin Cycle or Light Independent Reaction Also known as the Dark Reaction Also known as the Dark Reaction 10

RUDOLPH MARCUS 1992 Studied the Light Independent Reactions Studied the Light Independent Reactions First to describe the Electron transport Chain First to describe the Electron transport Chain

THE PHOTOSYNTHESIS EQUATION 12

PIGMENTS In addition to water, carbon dioxide, and light energy, photosynthesis requires Pigments In addition to water, carbon dioxide, and light energy, photosynthesis requires Pigments Chlorophyll is the primary light-absorbing pigment in autotrophs Chlorophyll is the primary light-absorbing pigment in autotrophs Chlorophyll is found inside chloroplasts Chlorophyll is found inside chloroplasts 13

LIGHT AND PIGMENTS Energy From The Sun Enters Earth’s Biosphere As Photons Energy From The Sun Enters Earth’s Biosphere As Photons Photon = Light Energy Unit Photon = Light Energy Unit Light Contains A Mixture Of Wavelengths Light Contains A Mixture Of Wavelengths Different Wavelengths Have Different Colors Different Wavelengths Have Different Colors 14

LIGHT & PIGMENTS Different pigments absorb different wavelengths of light Different pigments absorb different wavelengths of light Photons of light “excite” electrons in the plant’s pigments Photons of light “excite” electrons in the plant’s pigments Excited electrons carry the absorbed energy Excited electrons carry the absorbed energy Excited electrons move to HIGHER energy levels Excited electrons move to HIGHER energy levels 15

CHLOROPHYLL There are 2 main types of chlorophyll molecules: Chlorophyll a Chlorophyll b A third type, chlorophyll c, is found in dinoflagellates 16 Magnesium atom at the center of chlorophyll

CHLOROPHYLL A AND B 17

CHLOROPHYLL A Found in all plants, algae, & cyanobacteria Found in all plants, algae, & cyanobacteria Makes photosynthesis possible Makes photosynthesis possible Participates directly in the Light Reactions Participates directly in the Light Reactions Can accept energy from chlorophyll b Can accept energy from chlorophyll b 18

CHLOROPHYLL B Chlorophyll b is an accessory pigment Chlorophyll b is an accessory pigment Chlorophyll b acts indirectly in photosynthesis by transferring the light it absorbs to chlorophyll a Chlorophyll b acts indirectly in photosynthesis by transferring the light it absorbs to chlorophyll a Like chlorophyll a, it absorbs red & blue light and REFLECTS GREEN Like chlorophyll a, it absorbs red & blue light and REFLECTS GREEN 19

WHAT THEN IS PHOTOSYNTEHSIS? 20

WHAT IS PHOTOSYNTHESIS ? Involves the use of light Energy to convert Water (H20) and Carbon Dioxide (CO2) into Oxygen (O2) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches Involves the use of light Energy to convert Water (H20) and Carbon Dioxide (CO2) into Oxygen (O2) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches 21

PHOTOSYNTHESISOVERVIEW AUTOTROPHS AUTOTROPHS Plants and some other types of organisms that contain chlorophyll are able to use light energy from the sun to produce food. Plants and some other types of organisms that contain chlorophyll are able to use light energy from the sun to produce food. Make their own food using the sunlight 22

PHOTOSYNTHESISOVERVIEW HETEROTROPHS HETEROTROPHS Are organisms that can NOT make their own food Are organisms that can NOT make their own food They can NOT directly use the sun’s energy They can NOT directly use the sun’s energy 23

PHOTOSYNTHESISOVERVIEW Energy Energy Energy takes many forms such as light, heat, electrical, chemical and mechanical Energy takes many forms such as light, heat, electrical, chemical and mechanical Energy can be stored in chemical bonds and then released later on Energy can be stored in chemical bonds and then released later on 24

PHOTOSYNTHESISOVERVIEW Cells Use BIOCHEMICAL energy Cells use ATP for: Active transport Active transport Movement Movement Photosynthesis Photosynthesis Protein Synthesis Protein Synthesis Cellular respiration Cellular respiration All other cellular reactions All other cellular reactions 25

PHOTOSYNTHESISOVERVIEW ATP – Cellular Energy ATP – Cellular Energy Adenosine Triphosphate Adenosine Triphosphate Contains two, high-energy phosphate bonds Contains two, high-energy phosphate bonds Also contains the nitrogen base adenine and a ribose sugar Also contains the nitrogen base adenine and a ribose sugar 26

PHOTOSYNTHESISOVERVIEW ADP – Adenosine Diphosphate ADP – Adenosine Diphosphate ATP releases energy, a free phosphate, & ADP when cells take energy from ATP ATP releases energy, a free phosphate, & ADP when cells take energy from ATP 27

IMPORTANCE OF ATP Principal Compound Used To Store Energy In Living Organisms Principal Compound Used To Store Energy In Living Organisms 28

IMPORTANCE OF ATP ATP is constantly being used and remade by cells ATP is constantly being used and remade by cells ATP provides all of the energy for cell activities ATP provides all of the energy for cell activities The high energy phosphate bonds can be BROKEN to release energy The high energy phosphate bonds can be BROKEN to release energy The process of releasing ATP’s energy & reforming the molecule is called phosphorylation The process of releasing ATP’s energy & reforming the molecule is called phosphorylation 29

RELEASING ENERGY FROM ATP Adding A Phosphate Group To ADP stores Energy in ATP Adding A Phosphate Group To ADP stores Energy in ATP Removing A Phosphate Group From ATP Releases Energy & forms ADP Removing A Phosphate Group From ATP Releases Energy & forms ADP Lose Gain 30

ONE MORE THING ON ATP Cells Have Enough ATP To Last For A Few Seconds Cells Have Enough ATP To Last For A Few Seconds ATP must constantly be made ATP must constantly be made ATP Transfers Energy Very Well ATP Transfers Energy Very Well ATP Is NOT Good At Energy Storage ATP Is NOT Good At Energy Storage 31

32 PHOTOSYNTHESIS OVERVIEW

33 THE BIOCHEMICAL REACTIONS

34 IT BEGINS WITH SUNLIGHT!

35 PHOTOAUTOTROPHS ABSORB LIGHT ENERGY

36 INSIDE A CHLOROPLAST

37 STRUCTURE OF THE CHLOROPLAST Double membrane organelle Double membrane organelle Outer membrane smooth Outer membrane smooth Inner membrane forms stacks of connected sacs called thylakoids Inner membrane forms stacks of connected sacs called thylakoids Thylakoid stack is called the granum (grana-plural) Thylakoid stack is called the granum (grana-plural) Gel-like material around grana called stroma Gel-like material around grana called stroma

38 FUNCTION OF THE STROMA Light Independent reactions occur here Light Independent reactions occur here ATP used to make carbohydrates like glucose ATP used to make carbohydrates like glucose Location of the Calvin Cycle Location of the Calvin Cycle

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40 THYLAKOID MEMBRANES Light Dependent reactions occur here Light Dependent reactions occur here Photosystems are made up of clusters of chlorophyll molecules Photosystems are made up of clusters of chlorophyll molecules Photosystems are embedded in the thylakoid membranes Photosystems are embedded in the thylakoid membranes The two photosystems are: The two photosystems are: Photosystem I Photosystem I Photosystem II Photosystem II

41 PHOTOSYNTHESIS OVERVIEW

42 ENERGY CARRIERS Nicotinamide Adenine Dinucleotide Phosphate (NADP + ) Nicotinamide Adenine Dinucleotide Phosphate (NADP + ) NADP + = Reduced Form NADP + = Reduced Form Picks Up 2 high-energy electrons and H + from the Light Reaction to form NADPH Picks Up 2 high-energy electrons and H + from the Light Reaction to form NADPH NADPH carries energy to be passed on to another molecule NADPH carries energy to be passed on to another molecule

43 NADPH

44 Occurs across the thylakoid membranes Occurs across the thylakoid membranes Uses light energy Uses light energy Produce Oxygen from water Produce Oxygen from water Convert ADP to ATP Convert ADP to ATP Also convert NADP + into the energy carrier NADPH Also convert NADP + into the energy carrier NADPH LIGHT DEPENDENT REACTIONS

45 LIGHT DEPENDENT REACTION

46 LIGHT DEPENDENT REACTION

47 PHOTOSYSTEM I Discovered First Discovered First Active in the final stage of the Light Dependent Reaction Active in the final stage of the Light Dependent Reaction Made of 300 molecules of Chlorophyll Made of 300 molecules of Chlorophyll Almost completely chlorophyll a Almost completely chlorophyll a

48 PHOTOSYSTEM I High-energy electrons are moved to Photosystem I through the Electron Transport Chain Energy is used to transport H + from stroma to inner thylakoid membrane NADP+ converted to NADPH when it picks up 2 electrons & H+

49 PHOTOSYSTEM II Discovered Second Discovered Second Active in the beginning stage Of the Light Dependent Reaction Active in the beginning stage Of the Light Dependent Reaction Contains about equal amounts of chlorophyll a and chlorophyll b Contains about equal amounts of chlorophyll a and chlorophyll b

50 PHOTOSYNTHESIS BEGINS 1. Photosystem II absorbs light energy 2. Electrons are energized and passed to the Electron Transport Chain 3. Lost electrons are replaced from the splitting of water into 2H +, free electrons, and Oxygen 4. 2 H + pumped across thylakoid membrane

51 PHOSPHORYLATION Enzyme in thylakoid membrane called ATP Synthase As H+ ions passed through thylakoid membrane, enzyme binds them to ADP Forms ATP for cellular

52 LIGHT REACTION SUMMARY Reactants: H 2 O H 2 O Light Energy Light Energy Energy Products: ATP ATP NADPH NADPH

53 LIGHT INDEPENDENT REACTION ATP & NADPH from light reactions used as energy ATP & NADPH from light reactions used as energy Atmospheric C0 2 is used to make sugars like glucose and fructose Atmospheric C0 2 is used to make sugars like glucose and fructose Six-carbon Sugars made during the Calvin Cycle Six-carbon Sugars made during the Calvin Cycle Occurs in the stroma Occurs in the stroma

54 THE CALVIN CYCLE Two turns of the Calvin Cycle are required to make one molecule of glucose Two turns of the Calvin Cycle are required to make one molecule of glucose 3-CO 2 molecules enter the cycle to form several intermediate compounds (PGA) 3-CO 2 molecules enter the cycle to form several intermediate compounds (PGA) A 3-carbon molecule called Ribulose Biphosphate (RuBP) is used to regenerate the Calvin cycle A 3-carbon molecule called Ribulose Biphosphate (RuBP) is used to regenerate the Calvin cycle

55 THE CALVIN CYCLE

56 FACTORS AFFECTING THE RATE OF PHOTOSYNTHESIS Amount of available water Amount of available water Temperature Temperature Amount of available light energy Amount of available light energy

WORKSHEET TIME READING 57