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    Photosy Photosy Presentation Transcript

    • Photosynthesis Energy & Life copyright cmassengale
    • Overview of Photosynthesis copyright cmassengale
    • Autotrophs
        • Plants and some other types of organisms that contain chlorophyll are able to use light energy from the sun to produce food.
      copyright cmassengale
    • Autotrophs
      • Autotrophs include organisms that make their own food
      • Autotrophs can use the sun’s energy directly
      Euglena copyright cmassengale
    • Heterotrophs
      • Heterotrophs are organisms that can NOT make their own food
      • Heterotrophs can NOT directly use the sun’s energy
      copyright cmassengale
    • 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 copyright cmassengale
    • ATP – Cellular Energy
      • Adenosine Triphosphate
      • Contains two, high-energy phosphate bonds
      • Also contains the nitrogen base adenine & a ribose sugar
      copyright cmassengale
    • ADP
        • Adenosine Diphosphate
        • ATP releases energy , a free phosphate, & ADP when cells take energy from ATP
      One phosphate bond has been removed copyright cmassengale
    • Sugar in ADP & ATP
      • Called ribose
      • Pentose sugar
      • Also found on RNA
      copyright cmassengale
    • Importance of ATP
      • Principal Compound Used To Store Energy In Living Organisms
      copyright cmassengale
    • 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
      copyright cmassengale
    • Releasing Energy From ATP
      • Adding A Phosphate Group To ADP stores Energy in ATP
      • Removing A Phosphate Group From ATP Releases Energy & forms ADP
      Loose Gain copyright cmassengale
    • Cells Using Biochemical Energy
      • Cells Use ATP For:
      • Active transport
      • Movement
      • Photosynthesis
      • Protein Synthesis
      • Cellular respiration
      • All other cellular reactions
      copyright cmassengale
    • 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
      copyright cmassengale
    • Glucose
      • Glucose is a monosaccharide
      • C 6 H 12 O 6
      • One Molecule of glucose Stores 90 Times More Chemical Energy Than One Molecule of ATP
      copyright cmassengale
    • History of Photosynthesis & Plant Pigments copyright cmassengale
    • 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
      copyright cmassengale
    • Investigating Photosynthesis
        • Many Scientists Have Contributed To Understanding Photosynthesis
        • Early Research Focused On The Overall Process
        • Later Researchers Investigated The Detailed Chemical Pathways
      copyright cmassengale
    • 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?
      copyright cmassengale
    • 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
      copyright cmassengale
    • 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.
      copyright cmassengale
    • Ingenhousz’s Experiment 1779 Repeated Priestly experiment with & without sunlight copyright cmassengale
    • 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
      copyright cmassengale
    • Julius Robert Mayer 1845
      • Proposed That Plants can Convert Light Energy Into Chemical Energy
      copyright cmassengale
    • Samuel Ruben & Martin Kamen 1941
      • Used Isotopes To Determine That The Oxygen Liberated In Photosynthesis Comes From Water
      KAMEN RUBIN copyright cmassengale
    • 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
      copyright cmassengale
    • Rudolph Marcus 1992
      • Studied the Light Independent Reactions
      • First to describe the Electron transport Chain
      copyright cmassengale
    • The Photosynthesis Equation copyright cmassengale
    • 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
      copyright cmassengale
    • 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
      copyright cmassengale
    • 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
      copyright cmassengale
    • 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 copyright cmassengale
    • Chlorophyll a and b copyright cmassengale
    • Chlorophyll a
      • Found in all plants, algae, & cyanobacteria
      • Makes photosynthesis possible
      • Participates directly in the Light Reactions
      • Can accept energy from chlorophyll b
      copyright cmassengale
    • 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
      copyright cmassengale
    • The Biochemical Reactions copyright cmassengale
    • It Begins with Sunlight! copyright cmassengale
    • Photoautotrophs Absorb Light Energy copyright cmassengale
    • Inside A Chloroplast copyright cmassengale
    • 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
      copyright cmassengale
    • Function of the Stroma
      • Light Independent reactions occur here
      • ATP used to make carbohydrates like glucose
      • Location of the Calvin Cycle
      copyright cmassengale
    • copyright cmassengale
    • 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
      copyright cmassengale
    • Photosynthesis Overview copyright cmassengale
    • 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
      copyright cmassengale
    • NADPH copyright cmassengale
      • Occurs across the thylakoid membranes
      • Uses light energy
      • Produce Oxygen from water
      • Convert ADP to ATP
      • Also convert NADP + into the energy carrier NADPH
      Light Dependent Reactions copyright cmassengale
    • Light Dependent Reaction copyright cmassengale
    • Light Dependent Reaction copyright cmassengale
    • Photosystem I
        • Discovered First
        • Active in the final stage of the Light Dependent Reaction
        • Made of 300 molecules of Chlorophyll
        • Almost completely chlorophyll a
      copyright cmassengale
    • Photosystem II
        • Discovered Second
        • Active in the beginning stage Of the Light Dependent Reaction
        • Contains about equal amounts of chlorophyll a and chlorophyll b
      copyright cmassengale
    • 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
      copyright cmassengale
    • 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+
      copyright cmassengale
    • Phosphorylation
      • Enzyme in thylakoid membrane called ATP Synthase
      • As H+ ions passed through thylakoid membrane, enzyme binds them to ADP
      • Forms ATP for cellular
      copyright cmassengale
    • copyright cmassengale
    • Light Reaction Summary
      • Reactants:
      • H 2 O
      • Light Energy
      • Energy Products:
      • ATP
      • NADPH
      copyright cmassengale
    • 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
      copyright cmassengale
    • The Calvin Cycle copyright cmassengale
    • 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 (PGA)
      • A 3-carbon molecule called Ribulose Biphosphate (RuBP) is used to regenerate the Calvin cycle
      copyright cmassengale
    • copyright cmassengale
    • Factors Affecting the Rate of Photosynthesis
      • Amount of available water
      • Temperature
      • Amount of available light energy
      copyright cmassengale
    • copyright cmassengale