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Photosynthesis Acquiring Energy From Light

Photosynthesis Acquiring Energy From Light. What is Photosynthesis? Click me. Photosynthesis is a two stage process by which Light, Water and Carbon dioxide are used to make high energy compounds Glucose (carbohydrates). PHOTOSYNTHESIS: Chemical equation:

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Photosynthesis Acquiring Energy From Light

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  1. PhotosynthesisAcquiring Energy From Light What is Photosynthesis?Click me • Photosynthesis is a two stage process by which Light, Water and Carbon dioxide are used to make high energy compounds Glucose (carbohydrates). • PHOTOSYNTHESIS: • Chemical equation: • Reactants (needed)  Products (what is produced) • 12H2O +6CO2  C6H12O6 + 6O2 + 6H2O • Simplified: • 6H2O + 6CO2 [C6H12O6] + 6O2 sunlight energy-

  2. Light energy Chemical energy SUGARS SUN ATP, NADPH (C6H1206) H20 Light- Dependent Reactions (photophosphorylation) O2 Light ATP, NADPH “chemical energy” CO2 Light- Independent Reactions (Calvin Cycle) C6H12 O6 “chemical energy”

  3. Light CO2 Sugars 3O2 Figure 8-7 Photosynthesis: An Overview 6H2O + 6CO2 ---sunlight energy-- C6H12O6+ 6O2 6CO2 6H2O Chloroplast Chloroplast Light NADP+ NADPH+ ADP + P ADP+P Light- Dependent Reactions Calvin Cycle Light-Independent Reactions Calvin Cycle Light Dependent Reactions ATP ATP NADPH NADPH C6H12O6

  4. Where Do These Reactions Take Place?click me

  5. Chloroplast Occurs in the chloroplast of plant and other autotrophs Thylakoid membranes

  6. Photosynthesis starts in the (thylakoid membrane system) of the chloroplasts

  7. Light Dependent Reaction The Making of Chemical Energy: PHOTOPHOSPHORYLATION Light energy is used to split water molecules (PHOTO) 6 Water molecules are split into atoms of Hydrogen and atoms of Oxygen Step 1-photolysis (click me) 6 H2O 12 H and 6 O2 Oxygen (O2) is by product in this reaction Step 2-phosphorylation H+ (hydrogen ions) from water are used to generate “Chemical energy” in the form of ATP and NADPH ADP  ATP NADP+ + HNADPH

  8. Figure 8-10 Light-Dependent Reactions Section 8-3 Chloroplast Hydrogen Ion Movement Photosystem II ATP synthase Inner Thylakoid Space The products of the light dependent reaction: Oxygen, ATP Thylakoid Membrane Stroma Electron Transport Chain Photosystem I ATP Formation

  9. The Role of Chlorophyllclick me • Light trapping pigment Chlorophyll is required for photosynthesis • Chlorophyll absorbs all light energy EXCEPT GREEN, green wavelengths are reflected, this is why leaves are perceived as green in color. • Fall colors of leaves result from the absence of chlorophyll and the presence of other pigments which reflect their respective colors • Ex. Carotene (reflects orange and red wavelengths of light).

  10. Figure 8-5 Chlorophyll Light Absorption Section 8-2 Absorption of Light by Chlorophyll a and Chlorophyll b Chlorophyll b Chlorophyll a V B G Y O R

  11. Light Independent reactions(Calvin Cycle) LIGHT INDEPENDENT REACTIONS: Also known as “Calvin cycle” and "Carbon Fixation " -does not depend on sunlight for energy and proceeds in the absence of sunlight The energy made in the light dependent reaction in the form of (ATP, NADP+H) reaction are “spent” to convert carbon compounds found in the plant cells into sugars like (glucose) C6H12O6 a carbohydrate end product.

  12. Video 5 Video 5 CARBON FIXATION The first step involves CO2 (carbon dioxide) combining with RUBP- a 5 carbon compound found in plants CO2 Enters the Cycle Energy Input ChloropIast 5-Carbon Molecules Regenerated 6-Carbon Sugar Produced Sugars and other compounds

  13. The Light-Independent Reactions “Carbon Fixation” Step 1) Carbon dioxide from the air is combined with a 5-carbon sugar RuBP(Ribulose biphosphate) 3 CO2 + 3 RuBP------> 6 PGA (each cycle) This forms a 6-carbon molecule PGA (Phosphoglycerate) Step 2) 12 ATP are "spent" to convert PGA to PGAL a 3-carbon molecule and 12 H (hydrogen) are added to the molecule 6 PGA + [Chemical Energy] 12 PGAL [12 ATP12 ADP] [12 NADP+H 12 NADP] =Phosphoglyeraldehyde “spending energy”

  14. Step 3) 6 additional ATP are "spent" to convert PGAL into sugar and recycle RuBP PGAL + PGAL--------> C6H12O6 + RuBP [6 ATP---> 6ADP] “energy spent” Summary: 18 ATP made in the light dependent reactions are "spent" in the light independent reaction to make one molecule of PGAL Two cycles of the Calvin Cycle = 2PGAL Total cost is 36 ATP+2PGAL=1glucose (sugar)

  15. Light- dependent reactions Calvin cycle Energy from sunlight Thylakoid membranes CO2 ATP NADPH Stroma High-energy sugars ATP NADPH O2 Chloroplasts Concept Map Section 8-3 Photosynthesis includes takes place in uses use take place in H2O to produce to produce of

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