Download
photosynthesis n.
Skip this Video
Loading SlideShow in 5 Seconds..
Photosynthesis PowerPoint Presentation
Download Presentation
Photosynthesis

Photosynthesis

188 Views Download Presentation
Download Presentation

Photosynthesis

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Photosynthesis

  2. Introduction • 6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2 • Photosynthesis consists of two independent pathways called the light-dependent reaction (light reaction) and the light-independent reaction (dark reaction).

  3. Introduction • Light Reactions: the energy in sunlight is trapped, O2 is released, and both ATP and NADPH + H+ (hydrogen-carrier molecule) are formed • Dark Reactions: the ATP and NADPH + H+ react with CO2 from the atmosphere and form glucose • The entire process results in the transformation of light energy from the sun into energy stored in the bonds of the glucose molecule.

  4. Structure of a Chloroplast • The light reactions take place in the thylakoid membrane • The dark reactions take place in the stroma

  5. Structure of a Chloroplast

  6. Electromagnetic Spectrum

  7. Why are plants green?

  8. Pigments • Pigments are light-absorbing compounds. • Pigments appear colored because they absorb light of certain wavelengths and reflect that of others. • Chlorophyll a is the primary pigment in green plants that absorbs red and blue/violet light and reflects green light.

  9. Light Reaction

  10. Light Reaction • Also called Light Dependent Reaction • Pigments that are in the chloroplasts intercept light and begin the light reactions of photosynthesis. • The light reactions occur in two photosystems (located in the thylakoid membrane): • Photosystem: a unit of several hundred chlorophyll a molecules and associated acceptor molecules -photosystem I (PSI) -photosystem II (PSII)

  11. Photosystems

  12. Sequence these in the order of occurrence of the light reactions: • Electrons of Photosystem II chlorophylls are excited • Electrons are transferred to NADP to form NADPH • Light strikes the leaf

  13. Sequenced in the order of occurrence of the light reactions: • Light strikes the leaf • Electrons of Photosystem II chlorophylls are excited • Electrons are transferred to NADP to form NADPH

  14. Excited Electrons

  15. NADPH • NADP+ is an electron acceptor • NADP+ + 2 e- + 2 H+ NADPH + H+

  16. Primary Electron Acceptor ETC Proton Pump Thylakoid Water (H2O) Oxygen (O2) Hydrogen Ion (H+) Electron ATP Synthase PSI PSII Lumen

  17. Dark Reaction

  18. Dark Reaction • The dark reaction is also known as the Calvin Cycle, after an American scientist (Melvin Calvin) who figured out the pathway. • The dark reaction is also known as the C3 Cycle because the first stable products of this pathway are molecules that contain three carbon atoms. • The Calvin Cycle occurs in the stroma.

  19. 6 CO2 C unstable compound 6 RuBP C C C C C C C C C C C C C C C C C C C C C C C C C C 12 PGA Glucose 12 PGAL 2 PGAL 6 ATP ~ e 12 ATP 6 ADP + P ~ e 10 PGAL 12 ADP + P 12 NADPH + H+ e- 12 NADP+

  20. Cells convert the storage bond energy to the phosphate bonds of ATP in the process of respiration.

  21. ATP Adenosine triphosphate

  22. ATP – P = ADP • ADP + P = ATP

  23. Adenosine Diphosphate 7.3 kcal/mole energy released

  24. Adenosine Monophosphate

  25. Adenosine Diphosphate 7.3 kcal/mole energy released

  26. Adenosine Triphosphate

  27. T/F Questions • ATP has more energy than ADP.

  28. T/F • There are three phosphate atoms in ATP?

  29. T/F • You are storing energy right now in your body in the phosphate bonds of ATP.

  30. T/F • ATP is made of a sugar, the base adenine and a phosphate.

  31. Stomata