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Background information before Photosynthesis

Background information before Photosynthesis. ATP cycle Redox reactions Electron Transport Chain (ETC) Coenzymes (NADP). ATP Cycle. Adenosine Triphosphate is an energy carrying molecule. Adenosine + Phosphate + Phosphate + Phosphate

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Background information before Photosynthesis

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  1. Background informationbefore Photosynthesis ATP cycle Redox reactions Electron Transport Chain (ETC) Coenzymes (NADP)

  2. ATP Cycle • Adenosine Triphosphate is an energy carrying molecule. • Adenosine + Phosphate + Phosphate + Phosphate • When there is a demand for energy in our cells, enzymes break the last bond (+) releasing useable energy, producing: • Adenosine + Phosphate + Phosphate + Phosphate • (ADP + Phosphate + energy release) • Dephosphorylation – Exergonic reaction

  3. ATP Cycle • After cellular respiration, a lot of energy is release from the break down of glucose. • This energy can be used to attach free phosphates to ADP to produce ATP. In fact there is enough energy released to require the formation of 36 ATP molecules. • Phosphorylation- attachment of a phosphate group • Phosphorylation - Endergonic • This breaking down and building up of ATP is called the ATP cycle • Other reactions where ATP is formed: Glycolysis and the Light Reaction of photosynthesis

  4. ATP Cycle

  5. ATP Cycle • What is ATP? • ATP cartoon

  6. Redox Reactions • Reduction is gaining electrons/hydrogen (and usually some energy) • Oxidation is losing electrons/hydrogen (and usually some energy. • OIL RIG • During most chemical reactions, electrons are being lost or gained by atoms that make up molecules. • Molecules that gain electrons are said to be reduced and molecules that lose electrons are said to be oxidized

  7. Electron Transport Chain • - a series of redox reactions that transport electrons • 2e- Energy Coe + ADP + P = ATP Coe Coe Coe Coenzyme

  8. Electron Transport Chain • When a coenzyme grabs 2 electrons, it has been reduced. • When the coenzyme releases the electrons, it has been oxidized, and energy is released. • Using this energy to attach a phosphate to ADP is called Oxidative Phosphorylation. • If some protons are waiting at the bottom of the ETC, they join with the electrons to form Hydrogen atoms

  9. Coenzymes • Coenzymes are organic molecules that act as electron carriers, or Hydrogen carriers. • The coenzyme that functions in photosynthesis is Nicotinamideadeninedinucleotidephosphate • Ok, it is really 4 words, and we can call it NADP • NADP + 2H NADPH2

  10. Photosynthesis • Divided into 2 stages, the Light Reaction and the Dark Reaction • Balanced chemical equation: • 6 CO2 + 12 H2O + Light C6H12O6 + 6O2 + 6H2O • DR LR DR LR DR

  11. Chloroplast

  12. Light Reaction • Can only take place in the presence of light energy • Happens in the thylakoid disks • Consists of 3 reactions that are happening at the same time and are interdependent. • Photosystem 1 (PS1) • Photosystem 2 (PS2) • Photolysis

  13. Electromagnetic Spectrum

  14. Products of the Light Reaction • The “Light Reaction” is considered the power phase • The products of the Light Reaction are • ATP – provide a source of energy for the Dark Reaction (and some phosphates) • NADPH2 – provide H for the Dark Reaction (and a little energy)

  15. Photosystem 1 • Chlorophyll of PS1 absorbs energy and becomes “excited” (EM spectrum?) • Chlorophyll loses 4 electrons • This creates a problem: “chlorophyll ain’t chlorophyll no more” • PS2 to the rescue!

  16. Photosystem 2 • Chlorophyll of PS2 absorbs light energy • Chlorophyll loses 4 electrons • These electrons move along an ETC and replace the electrons lost in PS1 • As they move along the ETC, energy is given off and used to produce ATP. • For every pair of electrons moved, enough energy is released to synthesize 1 ATP, therefore …. • One problem solved……. • One problem created……

  17. PS2 continued • Chlorophyll of PS1 has been restored • Chlorophyll of PS2 is missing electrons • Have no fear! • Photolysis to the rescue!

  18. Photolysis • - breakdown of water, in the presence of sunlight. • 2 H2O + sunlight = 4 Hydrogen atoms + 2 oxygen atoms. • 4 H separate into 4 electrons (-) and 4 protons (+) • 2 O join to form O2 (atmospheric oxygen gas)

  19. What happens to the products of Photolysis? • 4 electrons – replace those lost from PS2 • 4 protons - join with the original electrons lost from PS1 to form 4 hydrogen atoms • O2 is released into the atmosphere • The 4 hydrogen atoms are picked up by the coenzyme (hydrogen carrier) NADP • 2 NADP + 4 H = 2NADPH2 • 2NADPH2 carry hydrogen atoms to the Dark Reaction

  20. How many ATP are produced in the Light Reaction? • 2 ATP come from the ETC • A third ATP is produced when sunlight provides the energy needed to attach a phosphate to an ADP molecule…..this is called • Photophosphorylation

  21. End products of the Light Reaction • 2 NADPH2 – carry hydrogen atoms to the Dark Reaction (and some energy) • 3 ATP – provide energy for the Dark Reaction (and some phosphates)

  22. Light Reaction Summary

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