Lecture5Light&Pigments

Lecture5Light&Pigments - Physical and Biological...

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Unformatted text preview: Physical and Biological Factors and Processes That Affect Life in the Ocean Ocean 1. 2. 3. 4. 5. 6. 7. 8. Light Temperature Dissolved Nutrients Diffusion, Osmosis, Passive & Active Diffusion, Transport Transport Salinity pH Dissolved Gases Hydrostatic Pressure Light in the Ocean Light Critical for photosynthesis to proceed Availability decreases exponentially with Availability depth in the ocean depth Lig ht with de pth, Ne us e Rive r Es tuary, NC Lig ht time o f day (s urfac e ), Ne us e Rive r Es tuary, NC Wavelength of light (nanometers) The electromagnetic spectrum Light is a rainbow of colors = light quality The color spectrum of light varies with depth varies Blue light penetrates deep; Blue red light is attenuated quickly red Depth of light penetration is Depth affected by particles and dissolved substances in the water water Light wavelength = color 400-700 nm is PAR 400-700 (Photosynthetically Available Radiation); visible light Radiation); Bottom line: Light availability drives photosynthetic reactions = results in primary production Photosynthesis vs. Primary Production Production Photosynthesis = The process by which carbohydrates are synthesized from carbon dioxide and water using light as an energy source. Most forms of photosynthesis release oxygen as a byproduct. oxygen Done by: plants, some bacteria (e.g. cyanobacteria), Done protistans (phytoplankton) protistans Primary production = the synthesis of organic materials from inorganic substances by photosynthesis or chemosynthesis chemosynthesis Some definitions Some Autotroph = “self nourishing”; makes own food from raw materials & energy food Photoautotroph = uses sunlight as energy source source Chemoautotroph = uses chemical energy (methane or hydrogen sulfide) as an energy source energy Heterotroph = must feed on autotrophs (most bacteria, animals) (most Photosynthesis is the main pathway by which carbon and energy enter the food web energy 12H2O + 6CO2 Water Carbon Dioxide 6O2 + C2H12O6 + 6H2O Oxygen Glucose Water Each of these dots is a chloroplast e.g. in the diatom Rhizosolenia castracanei… Photosynthetic reactions occur in the chloroplasts of photosynthetic cells (cells specialized for photosynthesis). two outer membranes inner membrane system (thylakoids all connected by channels) stroma channel stacked part of thylakoid membrane sunlight water uptake carbon dioxide uptake ATP LIGHT DEPENDENT REACTIONS (thylakoid) ADP + Pi NADPH NAD+ NADP+ LIGHT INDEPENDENT REACTIONS (stroma) P oxygen release glucose new water Photosynthesis occurs in two stages: The Light-Dependent & the Light-Independent Reactions Light Capture High energy Low energy Wavelength of light (nanometers) Visible light is a rainbow of colors = light “quality” Photosynthetic organisms use pigments to capture light of various colors Pigments are the “molecular bridge” between sunlight and photosynthesis Chlorophyll a Chlorophyll a is the main light harvesting pigment in most photosynthetic organisms Oceanographers measure this as a “proxy” for phytoplankton biomass Helping the chlorophylls are a group of accessory pigments Carotenoids are a group of accessory pigments These differ in the kinds and amounts between species/algal groups β -carotene Relative absorption beta-carotene phycoerythrin (a phycobilin) chlorophyll a chlorophyll b wavelength (nanometers) wavelength (nanometers) Each pigment contains a group of atoms that can absorb photons of different energies, which correspond to different colors of light (combined absorption efficiency across entire visible spectrum) chlorophyll b chlorophyll a chlorophyll a carotenoids chlorophyll b phycoerythrin phycocyanin (a phycobilin) (a phycobilin) Why do green plants or algae look green? ...
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