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Photosynthesis
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Photosynthesis Photosynthesis: ability of plant to capture light energy and turn it into the chemical energy of organic food molecules. (i.e. how plants make their food) ‘photo’ = light; ‘synthesis’ = to make (to make with light) Occurs in plant chloroplasts
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Chloroplast review Thylakoid membrane contains chlorophylls Chlorophyll = green pigment in chloroplasts that absorbs light Starch granules are present in the stroma of the chloroplast Granum (stacks of thylakoids) Thylakoids Stroma Lamellae
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Photosynthesis (continued) Produce glucose and ATP Involves a series of enzyme-controlled reactions, and can be summarized as: CO 2 + water Glucose + oxygen + water
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The phases Photosynthesis consists of 2 phases: 1.The Light dependent phase: need light 2.The Light independent Phase/Dark Phase: Does not need light
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The Light reaction/ Light Phase Occurs in the grana of the chloroplast Light energy (trapped by chloroplast) is used in two ways: 1. Make ATP: Light + ADP + P ATP ATP produced directly from light captured by chlorophyll (light energizes e - in chlorophyll molecule and the e - gets passed down an electron transport chain)
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2. Split water into hydrogen and oxygen Light + water + NADP NADPH 2 + Oxygen NADP (nicotinamide adenine dinucleotide phosphate) = hydrogen carrier molecule Oxygen produced diffuses out of cell (waste) _____________________________________ LIGHT REACTIONS: - Convert light energy chemical energy (NADPH 2 and ATP) (NADPH 2 and ATP) - These energy-rich compounds are used in the Dark Reactions…
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The phases Photosynthesis consists of 2 phases: 1.The Light dependent phase: need light 2.The Light independent Phase/Dark Phase: Does not need light (OK, I kinda lied…the H from the light phase is needed here…)
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The Light independent Phase/ Dark Phase Also called Calvin cycle/ Carbon fixation stage Occurs in the stroma of the chloroplast Uses the ATP and Hydrogen produced in the Light Phase (ATP and H travels from the grana to the stroma) CO 2 + ATP + Hydrogen G-3-P + water (G-3-P = Glyceraldehyde-3-phosphate)
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G-3-P is converted into: - Carbohydrate (glucose or sucrose) - Amino acid - lipid Glucose formed is often turned into insoluble starch (granules in stroma) Dark reaction (continued)
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Summary
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I Need a Little Light By Ross Durand copyright 2003 http://www.songplanet.com/artists/bands/669/ http://www.songplanet.com/artists/bands/669/ http://www.songplanet.com/artists/bands/669/ I need a little light So I can store energy I need a little light So I can make ATP I need a little light I’m gonna make some food It’s outta sight And I need a little light Been sittin here in this chloroplast, feeling green the whole day through Yeah, I’m a little thylakoid, just waitin’ for something to do I’m gonna move some electrons through a chain and pump some hydrogen in But it’s been dark all night and you can see the state I’m in
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I need a little light So I can store energy I need a little light So I can make ATP I need a little light I’m gonna make some food It’s outta sight And I need a little light When the electrons leave that chain they’re gonna join NADP (plus) And that high concentration of hydrogen’s gonna want outside of me Gonna go through a special protein that’s gonna kick some ATP out That’s what movin these electrons is really all about
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I need a little light So I can store energy I need a little light So I can make ATP I need a little light I’m gonna make some food It’s outta sight And I need a little light The ATP and NADPH are gonna make a cycle go round At the end of the calvin cycle glucose can be found You gotta put in 6 pieces of CO2 to make that precious food And use up the products of the thylakoid, darn this system’s good
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I need a little light So I can store energy I need a little light So I can make ATP I need a little light I’m gonna make some food It’s outta sight And I need a little light There’s one other thing that I need besides light It’s good old water You see that chlorophyll that loses those electrons – needs to get some back And that’s what the water does Now the whole reason that electron move was because of the light
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I need a little light So I can store energy I need a little light So I can make ATP I need a little light I’m gonna make some food It’s outta sight And I need a little light
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Factors affecting Photosynthesis 1.Light wavelength: chlorophyll absorbs all wavelengths of light except green (red and blue absorbed the most). rate of photosynthesis with red and blue light 2.Light intensity: light intensity rate of Photosynthesis 3.[Carbon dioxide]: photosynthesis limited by rate of CO 2 absorption 4.Temperature: temp rate (until 40 ° C) e.g. plants grow faster in glasshouse
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Factors affecting Photosynthesis (continued) 5.Water: water rate of photosynthesis 6.[Chlorophyll]: magnesium needed for a functional chlorophyll. Low Mg soil less chlorophyll. Plants often turn yellow from lack of chlorophyll (growth rate very slow in these plants)
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http://www.sumanasinc.com/webcontent/ animations/content/harvestinglight.html http://www.sumanasinc.com/webcontent/ animations/content/harvestinglight.html http://www.sumanasinc.com/webcontent/ animations/content/harvestinglight.html
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Mini Quiz 1.Photosynthesis consists of 2 phases – what are the two phases called? 2.The light reaction occurs within the ________ (structure) in the ____________ (organelle) 3.CO 2 + H 2 O _______ + _______ + H 2 O 4.How is the light energy captured from chlorophyll used? (2 ways) 5.What is the name of the hydrogen carrier molecule in the light reaction? Light and Dark Phases/ Light dependent phase and Light independent phase Grana Chloroplast Glucose Oxygen To make ATP and to split water into hydrogen and oxygen NADP
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Respiration and Photosynthesis sheet Use the resources provided to you (books, laptops, me…) to complete the sheet as a summary/review. Good sites to go to (for in-depth info) http://www.biologymad.com/ http://www.s- cool.co.uk/topic_index.asp?subject_id=3&d=0 http://www.bbc.co.uk/scotland/education/bitesize/hi gher/biology/cell_biology/index.shtml
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