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Biology 12 - Plants and Carbon dioxide - Section 7-3

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Biology 12 - Plants and Carbon dioxide - Section 7-3

Text of Biology 12 - Plants and Carbon dioxide - Section 7-3

  • 1. UNIT A: Cell BiologyChapter 2: The Molecules of CellsChapter 3: Cell Structure and FunctionChapter 4: DNA Structure and GeneExpressionChapter 5: Metabolism: Energy andEnzymesChapter 6: Cellular RespirationChapter 7: Photosynthesis: Section 7.3

2. UNIT A Chapter 7: PhotosynthesisIn this chapter you will learn how certain pigments, like the onesthat give leaves their particular colours, trap energy from the Sunand use it for photosynthesis.TO PREVIOUS SLIDEChapter 7: PhotosynthesisWhich pigments provide themaximum efficiency for a plant asit conducts photosynthesis?Why do leaves appear green inthe spring and summer and thenturn to red or yellow in the fall? 3. UNIT A Chapter 7: Photosynthesis Section 7.37.3 Plants as Carbon Dioxide FixersThe Calvin cycle reactions use atmospheric CO2 to producecarbohydrate. The cycle is divided into three sections:1.Fixation of carbon dioxide: carbon dioxide fixationinvolves reaction between CO2 and RuBP (a 5-carbonmolecule) Three CO2 and three RuBP react to produce three 6-carbon molecules; these split forming six 3-carbonmolecules (3-phosphoglycerate (3PG)) ATP is used RuBP carboxylase catalyzes the reaction; it is highlyabundant in the cellTO PREVIOUS SLIDE 4. UNIT A Chapter 7: Photosynthesis Section 7.3Calvin Cycle Reactions2. Reduction of carbon dioxide: 3PG is reduced to G3P andNADPH is oxidized to NADP+ Each 3PG undergoes reduction to G3P in two steps ATP and NADPH are usedTO PREVIOUS SLIDE 5. UNIT A Chapter 7: Photosynthesis Section 7.3Calvin Cycle Reactions3. Regeneration of RuBP: the starting material of the Calvincycle (RuBP) is replaced. ATP is used It takes three turns of the Calvin cycle for one G3P toexit. For every three turns, five G3P are used to re-formthree RuBP and the cycle continuesTO PREVIOUSSLIDE 6. UNIT A Chapter 7: Photosynthesis Section 7.3The CalvinCycleTO PREVIOUSSLIDEFigure 7.9 The Calvincycle reactions. 7. UNIT A Chapter 7: Photosynthesis Section 7.3The Importance of the Calvin CycleThe product of the Calvin cycle, glyceraldehyde-3-phosphate(G3P) can be converted to many other molecules.Glucose phosphate is made, which is the molecule mostoften metabolized for energyGlucose phosphate combines with fructose to producesucrose, which is used to transport carbohydrates withinplantsGlucose phosphate is used for synthesis of starch (storageform of glucose) and cellulose (in cell walls)G3P is also used for synthesizing fatty acids, glycerol, andamino acidsTO PREVIOUSSLIDE 8. UNIT A Section 7.3TO PREVIOUSSLIDEChapter 7: PhotosynthesisCheck Your Progress1. Describe how carbon dioxide is fixed and thenreduced to a carbohydrate.2. Illustrate why it takes three turns of the Calvin cycleto produce one glucose molecule.3. Explain why G3P is an important molecule in plantmetabolism. 9. UNIT A Section 7.3TO PREVIOUSSLIDEChapter 7: Photosynthesis