Chapter 10 - Photosynthesis Notes

Chapter 10 - Photosynthesis Notes - CHAPTER...

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CHAPTER 10-Photosynthesis   •  Life on  Earth  is solar  powered   •  Photosynthesis  nourishes  almost  all the  living  world  directly  or  indirectly ° All organisms  use  organic  compounds  for energy  and  for carbon  skeletons. ° Organism s  obtain  organic  compounds  by  one  of two major  mode s:  autotrophic  or  heterotrophic AUTOTROPHS (=producers)   •  produce  organic  molecules  from  CO 2  and other inorganic raw materials obtained from the environment   • ultimate source of organic compounds for heterotrophs Photoautotrophs use light as a source of energy to synthesize organic compounds.   • Photosynthesis occurs in plants, algae, some other protists, and some prokaryotes. Chemoautotrophs    • harvest energy from oxidizing inorganic substances, such as sulfur and ammonia   • unique to prokaryotes HETEROTROPHS (=consumers)    •  live  on  organic  compounds  produced  by  other  organism s    •  depend ent  on  photoautotrophs  for food  and  for oxygen  (by- product  of photosynthesis) PHOTOSYNTHESIS : converts  light energy  to the  chemical  energy  of food     6CO 2  + 6H 2 O + light energy   C 6 H 12 O 6  + 6O 2 • Happens in all green parts of plants but leaves = major site ~ about half a million chloroplasts/mm 2  of leaf surface • Color of leaf due to green pigment  chlorophyll Chloroplasts  mainly  in  mesophyll  cells  in the  interior  of the  leaf  30–40  chloroplasts/typical  mesophyll  cell O 2  and water vapor exits and CO 2  enters leaf through microscopic         pores on underside of leaf =  stoma (pl. stomata) GUARD CELLS control  openings-   OPEN if TURGID; CLOSED if FLACCID VEINS  bring  water  from  the  roots  and  carry  off sugar  from  mesophyll  cells  to nonphotosynthetic  areas  of plant          XYLEM- carries  water/ PHLOEM  carries  sugar/nutrients CHLOROPLAST :   Surrounded  by   DOUBLE  mem brane   Central  fluid filled  spac e  =  STROMA   System  of interconne cted  mem branous  sacs  =  THYLAKOIDS   Stack  of thylakoids  = GRANUM (pl. GRANA)   Fluid filled  compartment  inside  thylakoid             = THYLAKOID SPACE (lumen)   Chlorophyll  is located  in mem brane s  of thylakoid  sacs Photosynthetic  prokaryotes  lack  chloroplasts - photosynthetic  mem bran e s  = infolded  regions  of the  plasma  membrane LIGHT = form  of electromagn etic  radiation Energy  = inversely  related  to its wavelength      (ie,  shorter  wavelengths  pack  more  energy) Visible  light = 380- 750  nm
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PIGMENTS = light absorbing molecules   Only  chlorophyll   a participates directly in the light reactions;  • Other pigments have different absorption spectra; 
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Chapter 10 - Photosynthesis Notes - CHAPTER...

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