biology chapter 10 - Chapter 10: Photosynthesis Lecture 17...

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Chapter 10: Photosynthesis Lecture 17 The Process That Feeds the Biosphere - photosynthesis: convert solar energy to chemical energy stored in sugar and other organic molecules - autotrophs/ producers : self feeders, sustain themselves without eating anything derived from other living beings -produce organic molecules from CO2 and other inorganic materials obtained from the environment -plants are photoautotrophs : use light as a source of energy to synthesize organic substances -photosynthesis also occurs in algae, cetain other protests, and some prokaryotes - heterotrophs/consumers obtain organic material by 2 nd major mode of nutrition, live on compounds produced by other organisms…some digest other plants/animals, consume remains of dead organisms by decomposing/feeding organic litter (fungi) 10.1 P HOTOSYNTHESIS C ONVERTS L IGHT E NERGY TO THE C HEMICAL E NERGY OF F OOD -photosynthesis most likely originated in a group of bacteria that had infolded regions of the plasma membrane containing clusters of such molecules -in existing photosynthetic bacteria, infolded photosynthetic membranes function similarly to the internal membranes of the chloroplast -original chloroplast believed to be a photosynthetic prokaryote that lived inside a eukaryotic cell Chloroplasts: The Site of Photosynthesis in Plants -all green parts of a plant have chloroplasts, but leaves are major sites of photosynthesis in most plants -color from leaf from chlorophyll , green pigment located within chloroplasts -it is the light energy absorbed by chlorophyll that drives synthesis of organic molecules in the chloroplast -chloroplasts found mainly in cells of mesophyll -carbon dioxide enters the leaf, and oxygen exits by the stomata , pores -water absorbed by the roots is delivered to the leaves in veins ..also use veins to export sugar to roots and other nonphotosyntehtic parts of the plant -typical mesophyll cell: 30-40 chloroplasts, each chloroplast measuring 2-4 um by 4-7 um -envelope of 2 membranes encloses the stroma, dense fluid within chloroplast - thylakoids : system of interconnected membranous sacs which segregates the stroma from another comparment, thylakoid space -thylakoid sacs stacked in columns, granum -chlorophyll resides in thylakoid membranes (infolded photosynthetic membranes of prokaryotes also called thylakoid membranes) Tracking Atoms Through Photosynthesis: Scientific Inquiry -in the presence of light, the green parts of plants produce organic compounds and oxygen from carbon dioxide and water - 6 CO2 + 12 H20 + Light energy C6H12O6 + 6 O2 + 6 H20 -use glucose to simplify relationship between photosynthesis and respiration, but direct product is actually a 3 carbon sugar that can be used to make glucose -water appears on both sides of the equation because 12 molecules are consumed and 6 molecules are formed -simplified equation by indicating only the net consumption of water 6 CO2 + 6 H20 + Light energy C6H12O6 + 6 O2 -dividing equation by 6 to put it in simplest possible form CO2 + H20 (CH2O) + O2
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biology chapter 10 - Chapter 10: Photosynthesis Lecture 17...

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