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In This Lesson: Photosynthesis (Lesson 2 of 3) Today is Thursday, October 29th, 2015 Pre-Class: Why are plants green? (Or why are the green parts of them green, at least?) Other stuff: Grab a [small] paper towel for your pair. Today’s Agenda • Photosynthesis • Photosynthesis • And maybe flamingos. http://www.harunyahya.com/kids/pictures/wallpaper1024/flamingo.jpg By the end of this lesson… • You should be able to identify the general input and output of the photosynthesis reactions. ATP Review • Think of ATP (Adenosine Triphosphate) as a molecule like a chocolate bar. – “Not another analogy!” • The cell can break off a square to make it ADP. – That releases energy. • The cell can put a square on (add a phosphate group to ADP, making ATP), but that’s hard to do. – You’d need to melt it down in an oven and re-form it. – That absorbs (uses) energy. Simple Diagram (worth sketching…no, really) http://mrsec.wisc.edu/Edetc/nanoquest/molecular_motor/images/atpenergy.jpg Watching Plants Grow • First, where is this in my book? – P. 204 and following… • As usual, here are the historic figures related to Photosynthesis: – Van Helmont – Priestley – Ingenhousz – [your name here] 1600s: Jan van Helmont • Belgian physician – tries to figure out if plants take mass from soil to grow so large. • Measured soil, planted a seed, and watered it. • Then he waited five years (!). The soil weighed the same as it did five years earlier. • CONCLUSION – The plant is using water (hydrate) to grow. – Importantly, plants gain their mass largely from CO2, not from water. – Jan van Helmont also coined the word “gas.” http://2.bp.blogspot.com/_XU9nEwykZRc/SkO5s53xzgI/AAAAAAAAACU/gUPGWU3wpbo/s320/van_Helmont.jpg Floating head! Spooky… 1700s: Joseph Priestley • English minister – noticed that a candle will go out if you put a glass ‘allo jar over it. guv’nah!! – Flames need oxygen as fuel. • However, if you put a leaf in there (he used mint), the candle burns longer. • CONCLUSION – Plants produce oxygen. – Priestley also named rubber. Hmmph. http://explorepahistory.com/images/ExplorePAHistory-a0h1r8-a_349.jpg Aside: Great Moments in Science • Turns out that Priestley wasn’t the first to discover oxygen, though he got all the credit. • Previously, Carl Scheele discovered oxygen and seven other elements, unfortunately receiving credit for none of them. • Also unfortunate: Scheele had a habit of tasting all the chemicals with which he worked. – He was found dead at the age of 43 surrounded by several toxic chemicals. 1700s: Jan Ingenhousz • Dutch scientist – noticed that air bubbles only form around aquatic (underwater) plants when they are in sunlight. – The air bubbles are oxygen from photosynthesis. • No bubbles formed in darkness. • CONCLUSION – Plants need sunlight to make oxygen. http://0.tqn.com/d/chemistry/1/0/W/1/1/Jan_Ingenhousz.jpg I am grayscale. 2015: You. • Here’s an interesting question: – Suppose you put soil and some water in a clear jar. – Then you plant a seedling in that soil. – Then you put a lid on the jar, sealing the air. – Lastly, you set it on a windowsill so it gets a normal amount of light and heat. • What happens? The Magic Photosynthesis Machine ? INPUT YE OLDE PHOTOSYNTHESIS MACHINE ? OUTPUT Photosynthesis: An Outline • Photosynthesis is basically this: • 6CO2 + 6H2O + [LIGHT] C6H12O6 + 6O2 – In other words, it’s a conversion of light energy to chemical energy. – Plants use it to convert and store energy. • What you should do is this: – Write down the chemical formula. – Write down the formula in English. – Draw the formula in mini-diagrams. • (2 minutes to work) Photosynthesis • First, some review: (whiteboards) – In which organelle does photosynthesis occur? – What is a pigment? – What’s the name of the pigment inside chloroplasts? – What color is it? • Chlorophyll appears green to us because it is reflecting green light. Therefore, it’s absorbing every other color but green. The Big Aside • TED: David Gallo – Underwater Astonishments • Other people’s colors – Do I See Colors The Same Way You Do? – A Bee’s Eye View article • Ishihara Test • Stop sign color experiment and night vision – TED: Beau Lotto – Optical Illusions • • • • Primary colors Upside-down perception Vision correction Vision anomalies – TED: Michael Mauser – Floaters Ishihara Test http://www.toledo-bend.com Ishihara Test http://www.toledo-bend.com Perception • The image of the world around you strikes the retina in the back of the eye upside-down. – Your brain “flips” the image for you. Kinda. http://www.diycalculator.com/imgs/cvision-upside-down.gif Vision Correction http://www.d.umn.edu/~jfitzake/Lectures/DMED/Vision/Optics/Figures/RefractiveErrors.gif The Chloroplast Sketch it like you mean it! Grana Chloroplast Structure (It’s not just an oval) • Two membranes – The inside of the inner membrane is called the stroma. • Stacks of “disk-like structures.” (Holt: Biology) – The disks are called thylakoids. – The stacks are called grana (singular: granum). – Contain chlorophyll (pigment). • Light hits chlorophyll and chlorophyll reacts! RapidTrivia! • It’s time for something new I’m going to try. • Grab your whiteboards, grab your markers, and get your partner’s attention. • I’m going to post a series of trivia questions about today’s topics or recent ones, including an off-topic bonus question. • Write down your answers QUICKLY! – Got the right answer? Fantastic, give yourself a star. – Got the wrong answer? Write down the topic of the question and review it later. • Unless it’s the off-topic bonus question. Question #1 • What is the name of the innermost “space” of the chloroplast? – Stroma Question #2 • What is the name of the disk-like structures inside the chloroplasts? (just the disks, not the stacks!) – Thylakoids Question #3 • What are the two products of the photosynthesis reactions? – Sugar (glucose) and oxygen Question 4* • Why did bald eagles become so endangered in the mid-20th century? – DDT (dichlorodiphenyltrichloroethane) *Off-topic “Illuminating Photosynthesis” • Before we get to pigments and the “nuts and bolts” of this whole process, we’re going to see a really nice animation of the whole process in general. • Please take the time to read through it carefully – this will help! • It’s available here: – http://www.pbs.org/wgbh/nova/methuselah/phot_flash.html Photosynthesis: Pigments • There are three main pigments: – Chlorophyll A – Chlorophyll B – Carotenoids – There are also Anthocyanins – they help make leaves change color in the fall. • “Hard to place” fact: – Chlorophyll reflects green light! Carotenoids: A Brief Aside • In plants: – Carrots – Oranges – Fall leaves • In animals: – Flamingos – Zebra Finches – Et cetera http://www.rbgsyd.nsw.gov.au/__data/assets/image/0011/88535/Taeniopygia_guttata_Zebra_Finch_620.JPG I know you think my beak is attractive. Back on topic… http://www.pearsonsuccessnet.com/snpapp/iText/products/0-13-115075-8/text/chapter8/08images/08-02.gif Chloroplasts http://www.school.net.th/library/create-web/10000/science/10000-6528/pic2.jpeg Chloroplasts http://www.vialattea.net/spaw/image/biologia/May2005/thylakoids2.jpg Let’s summarize… Let’s summarize… Photosynthesis Lab Gizmo! • Today we’re going to look at a photosynthesis gizmo. Also please complete the Photosynthesis Lab Gizmo quiz on Quia. • [Log-in Instructions] Photosynthesis Reactions • There are two overall parts of Photosynthesis: – The Light Reactions (or Light-Dependent Reactions) • [because the plant needs light for them] – The Calvin Cycle (or Light-Independent Reactions) • Also called “The Dark Reactions” • [because the plant doesn’t need light for them] Light Reactions • • • • Where: The thylakoid membrane. Needs: Light and Water (H2O) Makes: ATP and protons (H+) Waste: Oxygen – Note: Even though oxygen is waste, it’s still a product. Photosynthesis Reactions 6CO2 + 6H2O C6H12O6 + 6O2 Light Reactions Light Reactions Light Reactions • Three Steps: – Light excites chlorophyll’s electrons (makes them go to higher energy). – Electrons travel down the thylakoid membrane as they lose energy. (leave some space in your notes) – The electrons power the thylakoid to make ADP into ATP. (leave some space in your notes) • This thing is called the electron transport chain, by the way, and it’s much like electricity flowing through a strand of holiday lights. e- Electron Transport Chain STROMA SPACE H+ e- THYLAKOID SPACE http://bioweb.wku.edu/courses/Biol120/images/non-cyclic1.jpg ETC • And what do those electrons power? – Electrons power a proton pump which brings protons into the thylakoid space. • And then… – Protons passively diffuse out through a protein/enzyme complex called ATP Synthase. • ATP Synthase “harvests” the motion of diffusion to synthesize ATP from ADP and free phosphate groups. – Much like a hydroelectric dam harvests water flow. The Calvin Cycle/Dark Reactions • Where: The Stroma • Needs: ATP and protons (H+) [from the Light Reactions] and CO2 [from the air] • Makes: Glucose (sugar/carbohydrate) • Side note: named after Melvin Calvin. Photosynthesis Reactions 6CO2 + 6H2O C6H12O6 + 6O2 Light Reactions Calvin Cycle Light Reactions Calvin Cycle Summary • The light reactions use sunlight to make ATP (and some by-products). • The dark reactions use that ATP to make glucose. Closure • First, let’s do a WhipAround, shall we? • Write down one new vocabulary word from today or yesterday and its definition. – Stand up once you’re done. • Now the Water Weed Lab. Closure • TED: Amanda Ooten – The Simple Story of Photosynthesis and Food