lecture 9 photosynthesis

lecture 9 photosynthesis - Lecture 9: Note Well continue...

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1 Lecture 9: Note We’ll continue with cellular respiration slides from Tuesday, then move on to these slides Photosynthesis: It Drives Our World! Thermodynamics in the Real World Energy flows into an ecosystem as sunlight and leaves as heat Light energy ECOSYSTEM CO 2 + H 2 O Photosynthesis in chloroplasts Cellular respiration in mitochondria Organic molecules + O 2 ATP powers most cel ular work Heat energy Figure 9.2 Photosynthesis Is the process that converts solar energy into chemical energy (a) Plants (b) Multicel ular algae (c) Unicel ular protist 10 μ m 40 μ m (d) Cyanobacteria 1.5 μ m (e) Pruple sulfur bacteria Figure 10.2 - Occurs in plants, algae, certain other protists, and some prokaryotes
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2 Autotrophs : Producers of the biosphere -plants: photoautotrophs -use light energy to make organic molecules from water and CO 2 Heterotrophs : “other feeders” -consumers of the biosphere (you and me!) -depend on photoautotrophs for food and O 2 Chloroplasts: The Sites of Photosynthesis in Plants The leaves of plants Are the major sites of photosynthesis Vein Leaf cross section Figure 10.3 Mesophyll CO 2 O 2 Stomata Pores through which CO 2 enters and O 2 exits Contains chloroplasts Chloroplasts The organelles in which photosynthesis occurs Contain thylakoids : membranous sacs where photosynthesis occurs and grana : stacks of thylakoids Chloroplast Mesophyl 5 μm Outer membrane Intermembrane space Inner membrane Thylakoid space Thylakoid Granum Stroma 1 μm Chloroplasts Split Water!!! Chloroplasts split water into Hydrogen and oxygen, incorporating the electrons of hydrogen into sugar molecules 6 CO 2 12 H 2 O Reactants: Products: C 6 H 12 O 6 6 H 2 O6 O 2 Figure 10.4
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3 Photosynthesis as a Redox Process Water is oxidized, carbon dioxide is reduced 6 CO 2 + 12 H 2 O + Light energy C 6 H 12 O 6 + 6 O 2 + 6 H 2 O The Reverse of Cellular Respiration! The Two Stages of Photosynthesis 1)The Light-dependent reactions Occur in the thylakoid grana Split water, releasing oxygen Produce ATP by chemiosmosis Form NADPH 2)The Calvin cycle (Dark Reactions) Occurs in the stroma Forms sugar from carbon dioxide, using ATP for energy and NADPH for reducing power (Carbon Fixation) An overview of photosynthesis H 2 O CO 2 Light LIGHT REACTIONS CALVIN CYCLE Chloroplast [CH 2 O] (sugar) NADPH NADP + ADP + P O 2 Figure 10.5 ATP Thylakoid grana Stroma The Light Reactions Light reactions convert solar energy to the chemical energy of ATP and NADPH
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4 The Nature of Sunlight Light Is a form of electromagnetic energy, which travels in waves Wavelength Is the distance between the crests of waves The length of the wave determines the type of electromagnetic energy Shorter wavelength= higher energy (inversely correlated) Photon -a discrete packet of light of fixed energy The electromagnetic spectrum Is the entire range of electromagnetic energy, or radiation Gamma rays X-rays UV Infrared Micro- waves Radio waves 10 –5 nm 10 –3 nm 1 nm 10 3 nm 10 6 nm 1 m 10 6 nm 10 3 m 380
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This note was uploaded on 11/02/2008 for the course BILD 1 taught by Professor Unk during the Spring '08 term at UCSB.

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lecture 9 photosynthesis - Lecture 9: Note Well continue...

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