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CHAPTER 8 Photosynthesis Sheldon: Revised 2011
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PLANTS USE SUNLIGHT ENERGY TO MAKE THEIR OWN FOOD You Tube Plants and Sunlight
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Where does your energy come from? Autotrophs Plants use sunlight to make their own food Heterotrophs Obtain energy from foods they consume (plants and animals)
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Energy in Chemical Bonds EXOTHERMIC: When a bond is broken, energy is released. ENDOTHERMIC: It takes energy in to hold bonds together.
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Endothermic or Exothermic? Endothermic Video (digital Thermometer)Endothermic Video Barium Hydroxide Octahydrate with Ammonium Thiocyanate (teacher)Barium Hydroxide Octahydrate with Ammonium Thiocyanate Exothermic Video (Fe2O3 + sugar)Exothermic Video Sodium and Water in Trash Can Exothermic Thermite Myth Busters Thermite Exothermic Make an Instant Cold Pack from Sodium Acetate (Nurd Rage) Supernova Make Glow Sticks - The ScienceSupernova Make Glow Sticks - The Science
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Cell’s Batteries ATP Adenosine Tri Phosphate VIDEO: howstuffworks (ATP)howstuffworks (ATP)
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CHARGED UNCHARGED
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Where might ATP be used? Used directly for: –Muscle movement –Synthesis of protein –Firefly flash –Sperm swimming –White blood cells moving YouTube MacrophageouTube Macrophage
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Photosynthesis is the most important chemical process on earth because: It provides food for virtually all organisms
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Overall Equation for Photosynthesis
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LIGHT AND PIGMENTS
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We see reflected wavelengths We don’t see absorbed wavelengths
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Chlorophyll The green pigment (light-absorbing molecules) in plants in their chloroplasts
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Light Spectrum From Sun
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Chlorophyll a and b Chlorophyll a Absorbs 430 + 662 nm Absorbs Blue- violet and red Chlorophyll b Absorbs 460 + 642 nm Absorbs Blue and orange-red
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Chlorophyll absorbs light well in these colors.
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Plants Reflect Green
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Also plants have other pigments: Carotenoids (orange) Phycoerythrin (red) Flavins (orange-yellow) Anthocyanin – blue-purple
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The Beginning of Photosynthesis Experiments What do you see? Photosynthesis History Video
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Photosynthesis History Van Helmont Plants gain most of their mass from H 2 O 1580-1644
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Priestley’s Experiment: Plants release O 2 sprig of mint Collected oxygen 1733- 1804
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Jan Ingenhousz 1730-1799 physician Light is necessary for plants to produce O 2 NO LIGHT-no oxygen
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LEAF INTERNAL STRUCTURE
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Cross Section of Leaf 5 2 9 3 8 1 7 4 6 10
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4. Mesophyll = middle leaf Made of: 6. Palisade Layer (vertical, tightly packed) + 7. Spongy Layer (has air spaces) Is where photosynthesis takes place
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6. Palisade Layer Tightly packed columns of plant cells
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Palisade Layer has lots of chloroplasts
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10. Air Space: Houses Gases in 7. Spongy Layer
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5. Cuticle Waxy covering of epidermis (reduces water loss)
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1. Stomata (pl.) (sing.= stoma) Opening to let gases and water vapor in and out Controlled by guard cells In lower epidermis
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8. Guard Cells Control the opening of the stoma Stoma LabBench
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LE 36-14 20 µm Which stoma is open and which is closed? You Tube Guard Cells
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LE 36-15a Cells turgid/Stoma open Changes in guard cell shape and stomatal opening and closing (surface view) Radially oriented cellulose microfibrils Vacuole Cell wall Guard cell Cells flaccid/Stoma closed
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LE 36-15b Cells turgid/Stoma open Role of potassium in stomatal opening and closing Cells flaccid/Stoma closed H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O K+K+
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9. Vein Xylem - tubes carrying water Phloem - tubes carrying food Leaf Cross Section Review
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Photosynthesis Intro VIDEO howstuffworks photosynthesis
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CHLOROPLASTS The photosynthesizing organelle
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Thylakoids Disks containing chlorophyll
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Grana (pl.) Granum (sing.) Stacks of thylakoid disks
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Stroma Cytoplasm of the chloroplast Where LIR (light independent reaction) occurs
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Light Dependent Reaction Occurs: thylakoid membrane Produce ATP and NADPH
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Vocabulary ATP production is called “photophosphorylation” (uses light) (adds P to ADP)
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Get Colored Pencils LDR and ILR Diagrams
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First LEO goes GER LEO = loss of electrons is oxidation GER = gain of electrons is reduction
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Redox Reactions
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oxidized reduced Gain H Lose H
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LDR Light Dependent Reaction
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Vocabulary PHOTOSYSTEM (or Reaction Center) uses light to energize molecules (electrons) PSI P700 PSII P680 (Absorb sunlight)
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1. Photon of light hits chlorophyll Excites an electron e- jumps around pigments until it hits chlorophyll a (reaction center) Demo with ping-pong balls!
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To ETC
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ETC (Electron Transport Chain) Accepts high energy electrons and moves them to low energy electrons The energy lost is given to an electron carrier ( NADP+) Virtual Cell: PhotosynthesisVirtual Cell: Photosynthesis
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e- flow to NADP+ to form NADPH NADPH is an electron carrier Nicotinamide Adenine Dinucleotide Phosphate.
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2. Water is Split Oxygen is released H+ ions build up in thylakoid interior Light reactions (click on the four steps)Light reactions PS II Kid Like Animation PSI
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3. H+ ions pumped through the thylakoid membrane H+ ions in chemiosmosis
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4. Chemiosmosis Build-up of H+ ions pumped through the ATP synthase to make ATP (P joins ADP)
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Summary of Energy transformation in the light reactions Light energy starts the process Flow of Electrons –Splitting of water molecules provides electrons –Release of oxygen molecules from water –Accumulation of H+ in thylakoid spaces –LDR VideoLDR Video
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Reduction of NADP to NADPH by adding electrons and H+ Production of ATP using the H+ in thylakoid spaces –ATP synthase enzyme –Powered by flow of H+ from the thylakoid spaces –ADP + Phosphate (Pi) ---> ATP –McGraw-Hill ETC and ATP SynthesisMcGraw-Hill ETC and ATP Synthesis
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PSI and PSII Animation You Tube PS II Photosynthesis AnimationVCAC: CellularYou Tube PS IIPhotosynthesis AnimationVCAC: Cellular
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LIR (Light Independent Reaction) aka Calvin Cycle Calvin Cycle
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LIR (Light Independent Reaction) aka Calvin Cycle Found: in the stroma of the chloroplast Does not need sunlight but is run by ATP and NADPH made in the LDR Here is where the carbohydrates are actually assembled McGraw-Hill Calvin Cycle
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Summary of the Calvin Cycle Addition (fixing) of gaseous CO 2 to RUBP, a 5 carbon compound in the stroma of chloroplasts. Energy input from ATP (ATP from the light reactions ---> ADP + Phosphate back to the light reactions) Addition of H+ and energy from NADPH
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Summary (cont.) (NADPH from the light reactions ---> NADP+ back to the light reactions Production of carbohydrates for storage, transport, and biosynthesis Recycling of 5 carbon compound (RUBP) to fix more CO 2
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Rubisco Most abundant protein in the world! Recyclable! Used in the first step of fixing (making useable) atmospheric CO 2 Attqaches 5-c sugar to CO 2 Ribulose-1,5-bisphosphate carboxylase oxygenase,
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Light Independent Reaction YouTube - The Calvin Cycle or (animated and narrated)YouTube - The Calvin Cycle or YouTube - Calvin Cycle Video (simple overview-animated diagram)YouTube - Calvin Cycle Video YouTube - Photosynthesis-Calvin Cycle and Cyclic Electron Flow (your fav science singer)YouTube - Photosynthesis-Calvin Cycle and Cyclic Electron Flow
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Now Sing Along YouTube - Photosynthesis - The Light Reactions YouTube - MY FAVE SONG: THE PHOTOSYNTHESIS SONGYouTube - MY FAVE SONG: THE PHOTOSYNTHESIS SONG YouTube - Photosynthesis Song (with subtitles) EXTRA CREDIT- 5 points You write the lyrics to a common song about photosynthesis. Must have at least 5 stanzas.
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OR Make a model of either the LDR or LIR or chloroplast Each must include at least 5 labeled items
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Label the thylakoid disk
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PSII PSI ATP Synthase stroma ETC Thylakoid interior
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Chloroplast
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A C E D B
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A C E D B
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F E D G C H B A
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Summary: From Leaf to Molecules Photosynthesis: The Movie Processes: Photosynthesis: The MoviePhotosynthesis: The MovieProcesses: Photosynthesis: The Movie
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What runs the LDR? What runs the LIR?
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What runs the LDR? sunlight What runs the LIR? ATP and NADPH
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Overview of Photosynthesis
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