Photosynthesis Photosynthesis The Photosynthesis Song - http://www.youtube.com/watch?v=C1_uez5WX1o Intro Video – http://www.youtube.com/watch?v=zEgIO9Kq2_Y Photosynthesis the Movie - http://vcell.ndsu.nodak.edu/animations/photosynthesis/movie.htm Photosynthesis

Objectives Summarize how energy is captured from sunlight during the light dependent reactions of photosynthesis. Analyze the function of electron transport chains during the light dependent reactions of photosynthesis. Relate the Calvin cycle to carbon dioxide fixation in photosynthesis. Identify three environmental factors that affect the rate of photosynthesis.

Stages of Photosynthesis Stage 1 Light-dependent reaction Chlorophyll pigments capture light energy Thylakoid membranes Stage 2 Light-dependent reaction Light energy converted to chemical energy. Production of ATP and NADPH 2 H+ + NADP+ --> NADPH + H+ in photosynthesis Stage 3 Light-independent reaction Reduction of CO2 to glucose: using ATP + NADPH + H+ to synthesize organic compounds (glucose) from CO2 (carbon fixation); process called Calvin cycle; Stroma © Teachable and Louise Edgeworth. Some rights reserved. http://teachable.net/res.asp?r=6615

The Dark Side You just made a bunch of ATP and NADPH from the light reactions. You now use these electrons and energy to put a bunch of carbons together to make glucose – this is the job of the Calvin cycle. The Calvin cycle can be broken down into three phases: Carbon fixation – Putting carbons together. Reduction reactions – Adding electrons & energy. Regeneration of RuBP – Getting back to the start – it is a cycle after all.

The Calvin Cycle! What is it? The Calvin Cycle uses ATP and NADPH from the light-dependent reactions and CO2 from the air to make high-energy sugars (glucose)! Glucose

Where does the Calvin Cycle occur? The Calvin Cycle occurs in the stroma of the chloroplast.

What parts of the photosynthesis equation are involved in the Calvin Cycle? CO2 is broken down to create glucose (C6H12O6) C6H12O6

Steps of the Calvin Cycle

Calvin Cycle – Carbon Fixation 1. Six CO2 molecules enter the leaf through the stoma and diffuse into the stroma. They are added to a 5 carbon compound (ribulose biphosphate (RuBP)) by an enzyme (rubisco – ribulose bisphosphate carboxylase).

Calvin Cycle – Carbon Fixation They are split into twelve 3-carbon compounds ( 3-phosphoglycerate (PGA)). Known as the C3 pathway because the first molecule made in this process has three carbons.

Calvin Cycle – Reduction Reactions Energy from ATP is used to phosphorylate the 3-carbon compounds (PGA) into 1,3-biphosphoglycerate A pair of electrons from NADPH reduces the 1,3-biphosphoglycerate to give G3P – glyceraldehyde 3-phosphate., a 3C Known as the C3 pathway because the first molecule made in this process has three carbons. What you have just done was add electrons to make bonds and a source of hydrogen for the glucose.

Calvin Cycle – Regeneration of RuBP 4. Two of the resulting 3-carbon sugars is used to make organic compounds – including GLUCOSE, starch and sucrose – in which energy is stored for later use by the organism.

Calvin Cycle – Regeneration of RuBP 5. The other ten 3-carbon sugars are used to regenerate the initial 5-carbon compound, (RuBP) thereby completing the cycle. This process consumes 6 molecules of ATP

Review of Calvin Cycle

Where does the Calvin Cycle occur? In the stroma of the chloroplast!

What goes into the Calvin Cycle? ATP and NADPH are used for energy CO2 is broken apart to create C6H12O6

Animation of Overview of Photosynthesis http://wps.prenhall.com/wps/media/objects/486/498596/CDA7_1/CDA7_1d/CDA7_1d.htm

Factors that Affect Photosynthesis Photosynthesis is directly affected by environmental factors such as: The intensity of light The concentration of carbon dioxide Temperature. Period 4 stopped here 10-7/10

PHOTOSYNTHESIS QUIZ 15 points Where in a plant cell does photosynthesis occur? What are the 2 stages of photosynthesis and where do they occur? Why are plants green? What is the balanced equation for photosynthesis? What are the reactants and products of the light dependent reactions? What are the reactants and products of the Calvin Cycle? What are two reasons we depend on plants for our survival?

Review Summarize how photosynthetic organisms capture the energy in sunlight. Compare the roles of water molecules and hydrogen ions in electron transport chains. Describe the role of the Calvin cycle in photosynthesis. Critical Thinking Organizing Information Make a table in which you identify the role of each of the following in photosynthesis: light, water, pigments. ATP. NADPH. and carbon dioxide.

5. Critical Thinking Inferring Relationships What combination of environmental factors affects the rate of photosynthesis? 6. Standardized Test Prep During photosynthesis, plants store energy in A ADP. B carbon dioxide. C 3-carbon sugars. D water.