Photosynthesis. Energy & Life

Transcription

1 Photosynthesis Energy & Life 1

2 Overview of Photosynthesis 2

3 Autotrophs Plants and some other types of organisms that contain chlorophyll are able to use light energy from the sun to produce food. 3

4 Autotrophs include organisms that make their own food Autotrophs Autotrophs can use the sun s energy directly Euglena 4

5 Heterotrophs are organisms that can NOT make their own food Heterotrophs can NOT directly use the sun s energy Heterotrophs 5

6 Energy Energy Takes Many Forms such as light, heat, electrical, chemical, mechanical Energy can be changed from one form to another Energy can be stored in chemical bonds & then released later Candles release energy as HEAT & LIGHT 6

7 ATP Cellular Energy Adenosine Triphosphate Contains two, high-energy phosphate bonds Also contains the nitrogen base adenine & a ribose sugar 7

8 ADP Adenosine Diphosphate ATP releases energy, a free phosphate, & ADP when cells take energy from ATP One phosphate bond has been removed 8

9 Sugar in ADP & ATP Called ribose Pentose sugar Also found on RNA 9

10 Importance of ATP Principal Compound Used To Store Energy In Living Organisms 10

11 Releasing Energy From ATP ATP is constantly being used and remade by cells ATP provides all of the energy for cell activities The high energy phosphate bonds can be BROKEN to release energy The process of releasing ATP s energy & reforming the molecule is called phosphorylation 11

12 Releasing Energy From ATP Adding A Phosphate Group To ADP stores Energy in ATP Removing A Phosphate Group From ATP Releases Energy & forms ADP Gain Loose 12

13 Cells Using Biochemical Energy Cells Use ATP For: Active transport Movement Photosynthesis Protein Synthesis Cellular respiration All other cellular reactions 13

14 More on ATP Cells Have Enough ATP To Last For A Few Seconds ATP must constantly be made ATP Transfers Energy Very Well ATP Is NOT Good At Energy Storage 14

15 Crash Course ATP fe=active 15

16 Glucose is a Glucose monosaccharide C 6 H 12 O 6 One Molecule of glucose Stores 90 Times More Chemical Energy Than One Molecule of ATP 16

17 History of Photosynthesis & Plant Pigments 17

18 Photosynthesis Involves the Use Of light Energy to convert Water (H 2 0) and Carbon Dioxide (CO 2 ) into Oxygen (O 2 ) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches 18

19 Investigating Photosynthesis Many Scientists Have Contributed To Understanding Photosynthesis Early Research Focused On The Overall Process Later Researchers Investigated The Detailed Chemical Pathways 19

20 Early Questions on Plants Several Centuries Ago, The Question Was: Does the increase in mass of a plant come from the air? The soil? The Water? 20

21 Van Helmont s Experiment 1643 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. Concluded Mass Came From Water 21

22 Priestley s Experiment 1771 Burned Candle In Bell Jar Until It Went Out. Placed Sprig Of Mint In Bell Jar For A Few Days. Candle Could Be Relit And Burn. Concluded Plants Released Substance (O 2 ) Necessary For burning. 22

23 Ingenhousz s Experiment 1779 Repeated Priestly experiment with & without sunlight 23

24 Results of Ingenhousz s Experiment Showed That Priestley s Results Only Occurred In The Presence Of Sunlight. Light Was Necessary For Plants To Produce The Burning Gas or oxygen 24

25 Julius Robert Mayer 1845 Proposed That Plants can Convert Light Energy Into Chemical Energy 25

26 Samuel Ruben & Martin Kamen 1941 Used Isotopes To Determine That The Oxygen Liberated In Photosynthesis Comes From Water RUBIN KAMEN 26

27 Melvin Calvin 1948 First to trace the path that carbon (CO 2 ) takes in forming Glucose Does NOT require sunlight Called the Calvin Cycle or Light Independent Reaction Also known as the Dark Reaction 27

28 Rudolph Marcus 1992 Studied the Light Independent Reactions First to describe the Electron transport Chain 28

29 The Photosynthesis Equation 29

30 Crash Course Photosynthesis afe=active 30

31 Pigments In addition to water, carbon dioxide, and light energy, photosynthesis requires Pigments Chlorophyll is the primary light-absorbing pigment in autotrophs Chlorophyll is found inside chloroplasts 31

32 Light and Pigments Energy From The Sun Enters Earth s Biosphere As Photons Photon = Light Energy Unit Light Contains A Mixture Of Wavelengths Different Wavelengths Have Different Colors 32

33 Light & Pigments Different pigments absorb different wavelengths of light Photons of light excite electrons in the plant s pigments Excited electrons carry the absorbed energy Excited electrons move to HIGHER energy levels 33

34 Chlorophyll There are 2 main types of chlorophyll molecules: Chlorophyll a Chlorophyll b A third type, chlorophyll c, is found in dinoflagellates Magnesium atom at the center of chlorophyll 34

35 Chlorophyll a and b 35

36 Chlorophyll a Found in all plants, algae, & cyanobacteria Makes photosynthesis possible Participates directly in the Light Reactions Can accept energy from chlorophyll b 36

37 Chlorophyll b Chlorophyll b is an accessory pigment 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 37

38 The Biochemical Reactions 38

39 It Begins with Sunlight! 39

40 Photoautotrophs Absorb Light Energy 40

41 Inside A Chloroplast 41

42 Structure of the Chloroplast Double membrane organelle Outer membrane smooth Inner membrane forms stacks of connected sacs called thylakoids Thylakoid stack is called the granun (grana-plural) Gel-like material around grana called stroma 42

43 Function of the Stroma Light Independent reactions occur here ATP used to make carbohydrates like glucose Location of the Calvin Cycle 43

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45 Thylakoid membranes Light Dependent reactions occur here Photosystems are made up of clusters of chlorophyll molecules Photosystems are embedded in the thylakoid membranes The two photosystems are: Photosytem I Photosystem II 45

46 Photosynthesis Overview 46

47 Energy Carriers Nicotinamide Adenine Dinucleotide Phosphate (NADP + ) NADP + = Reduced Form 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 47

48 NADPH 48

49 Light Dependent Reactions Occurs across the thylakoid membranes Uses light energy Produce Oxygen from water Convert ADP to ATP Also convert NADP + into the energy carrier NADPH 49

50 Light Dependent Reaction 50

51 Light Dependent Reaction 51

52 Photosystem I Discovered First Active in the final stage of the Light Dependent Reaction Made of 300 molecules of Chlorophyll Almost completely chlorophyll a 52

53 Photosystem II Discovered Second Active in the beginning stage Of the Light Dependent Reaction Contains about equal amounts of chlorophyll a and chlorophyll b 53

54 Photosynthesis Begins Photosystem II absorbs light energy Electrons are energized and passed to the Electron Transport Chain Lost electrons are replaced from the splitting of water into 2H +, free electrons, and Oxygen 2H + pumped across thylakoid membrane 54

55 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+ 55

56 Phosphorylation Enzyme in thylakoid membrane called ATP Synthase As H+ ions passed through thylakoid membrane, enzyme binds them to ADP Forms ATP for cellular respiration 56

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58 Light Reaction Summary Reactants: H 2 O Light Energy Energy Products: ATP NADPH 58

59 Light Independent Reaction ATP & NADPH from light reactions used as energy Atmospheric C0 2 is used to make sugars like glucose and fructose Six-carbon Sugars made during the Calvin Cycle Occurs in the stroma 59

60 The Calvin Cycle 60

61 The Calvin Cycle 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 A 3-carbon molecule called Ribulose Biphosphate (RuBP) is used to regenerate the Calvin cycle 61

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63 Factors Affecting the Rate of Photosynthesis Amount of available water Temperature Amount of available light energy 63

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