chapter 10 - Light energy ECOSYSTEM Photosynthesis CO2 +...

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1 Photosynthesis CO 2 + H 2 O C 6 H 12 O 6 + water + O 2 C 6 H 12 O 6 + water + O 2 CO 2 + H 2 O Respiration ECOSYSTEM Light energy Photosynthesis in chloroplasts Cellular respiration in mitochondria Organic molecules + O 2 CO 2 + H 2 O ATP powers most cellular work Heat energy Photoautotrophs Æ transform light energy into chemical energy Plants Unicellular protist Multicellular algae Cyanobacteria Purple sulfur bacteria 10 μm 1.5 μm 40 μm = 500 million years ago Earliest animals ; diverse algae Earliest multicellular eukaryotes ? Earliest eukaryotes ears ago Accumulation of atmospheric O 2 from photosynthetic cyanobacteria Oldest known prokaryotic fossils Origin of life ? Formation of Earth Billions of ye Rough endoplasmic reticulum Smooth endoplasmic reticulum Ribosomes (smal brown dots) Central vacuole Microfilaments Intermediate filaments Microtubules CYTOSKELETON Nuclear envelope Nucleolus Chromatin NUCLEUS Centrosome Golgi apparatus In plant cel s but not animal cel s: Chloroplasts Central vacuole and tonoplast Cel wal Plasmodesmata Chloroplast Plasmodesmata Wal of adjacent cel Cel wal Mitochondrion Peroxisome Plasma membrane Plant Eukaryotic Cell Photosynthesis takes place in chloroplasts Leaf cross section Vein Mesophyl Stomata CO 2 O 2 Mesophyl cel Chloroplast Remember REDOX? 5 μm Outer membrane Intermembrane space Inner membrane Thylakoid space Thylakoid Granum Stroma 1 μm Thylakoid membranes Stroma
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2 Thylakoids Æ light reactions H 2 O Light NADP + CO 2 ADP Stroma Æ Calvin Cycle LIGHT REACTIONS Chloroplast ATP NADPH O 2 P + i CALVIN CYCLE [CH 2 O] (sugar) Electromagnetic spectrum Æ visible light drives photosynthesis 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 9 nm) 10 3 m Visible light 380 450 500 550 600 650 700 750 nm Longer wavelength Lower energy Shorter wavelength Higher energy Chloroplast Light Chloroplasts have three types of pigments: Chlorophyll a Chlorophyll b carotenoids Absorbed light Transmitted light Granum Absorption spectra of chloroplast pigments help determine each pigment’s role in a plant White light Refracting prism Chlorophyll solution Photoelectric tube Galvanometer The high transmittance (= low absorption ) reading indicates that chlorophyll absorbs very little green light. Green Light 500-600 nm Slit moves to pass light of selected wavelength 0 100 White light Refracting prism Chlorophyll solution Photoelectric tube 0 100 The low transmittance (= high absorption ) reading indicates that chlorophyll absorbs most blue light. Blue Light 400-500 nm Slit moves to pass light of selected wavelength Chlorophyll a Chlorophyll b Carotenoids Absorption spectra Æ wavelengths of light absorbed by chloroplasts’ pigments f light by igments Wavelength of light (nm) Absorption o chloroplast p 400 500 600 700
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3 Action spectrum Æ rate of
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This note was uploaded on 04/16/2008 for the course BIO 131 taught by Professor Paz y mino during the Fall '08 term at UMass Dartmouth.

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chapter 10 - Light energy ECOSYSTEM Photosynthesis CO2 +...

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