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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 - PowerPoint PPT Presentation
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Background informationBackground informationbefore before PhotosynthesisPhotosynthesis1.1. ATP cycleATP cycle2.2. Redox reactionsRedox reactions3.3. Electron Transport Chain (ETC)Electron Transport Chain (ETC)4.4. Coenzymes (NADP)Coenzymes (NADP)
ATP CycleATP Cycle Adenosine Triphosphate is an energy carrying Adenosine Triphosphate is an energy carrying
molecule.molecule. Adenosine + Phosphate + Phosphate Adenosine + Phosphate + Phosphate ++ Phosphate Phosphate
When there is a demand for energy in our cells, When there is a demand for energy in our cells, enzymes break the last bond (enzymes break the last bond (++) releasing useable ) releasing useable energy, producing:energy, producing:
Adenosine + Phosphate + Phosphate Adenosine + Phosphate + Phosphate + Phosphate+ Phosphate (ADP (ADP + Phosphate + Phosphate + energy release)+ energy release) Dephosphorylation – Exergonic reactionDephosphorylation – Exergonic reaction
ATP CycleATP Cycle After cellular respiration, a lot of energy is release from the After cellular respiration, a lot of energy is release from the
break down of glucose.break down of glucose. This energy can be used to attach free phosphates to ADP to This energy can be used to attach free phosphates to ADP to
produce ATP. In fact there is enough energy released to produce ATP. In fact there is enough energy released to require the formation of 36 ATP molecules.require the formation of 36 ATP molecules.
Phosphorylation- attachment of a phosphate groupPhosphorylation- attachment of a phosphate group Phosphorylation - EndergonicPhosphorylation - Endergonic This breaking down and building up of ATP is called the This breaking down and building up of ATP is called the ATP ATP
cyclecycle Other reactions where ATP is formed: Other reactions where ATP is formed: Glycolysis Glycolysis and the and the
Light ReactionLight Reaction of photosynthesis of photosynthesis
Redox ReactionsRedox Reactions
Reduction is Reduction is gaining gaining electrons/hydrogen (and usually electrons/hydrogen (and usually some energy)some energy)
Oxidation is Oxidation is losing losing electrons/hydrogen (and usually electrons/hydrogen (and usually some energy.some energy.
OIL RIGOIL RIG During most chemical reactions, electrons are being During most chemical reactions, electrons are being
lost or gained by atoms that make up molecules.lost or gained by atoms that make up molecules. Molecules that gain electrons are said to beMolecules that gain electrons are said to be reduced reduced
and molecules that lose electrons are said to be and molecules that lose electrons are said to be oxidizedoxidized
Electron Transport ChainElectron Transport Chain
- a series of redox reactions that transport - a series of redox reactions that transport electronselectrons
2e2e- -
Coe
Coe
Coe
Coe
Energy
Coenzyme
+ ADP + P = ATP
Electron Transport ChainElectron Transport Chain
When a coenzyme grabs 2 electrons, it has When a coenzyme grabs 2 electrons, it has been been reduced.reduced.
When the coenzyme releases the electrons, it When the coenzyme releases the electrons, it has been has been oxidized,oxidized, and energy is released. and energy is released.
Using this energy to attach a phosphate to Using this energy to attach a phosphate to ADP is called ADP is called Oxidative Phosphorylation.Oxidative Phosphorylation.
If some protons are waiting at the bottom of If some protons are waiting at the bottom of the ETC, they join with the electrons to form the ETC, they join with the electrons to form Hydrogen atomsHydrogen atoms
CoenzymesCoenzymes
Coenzymes are organic molecules that act as Coenzymes are organic molecules that act as electron carriers, or Hydrogen carriers.electron carriers, or Hydrogen carriers.
The coenzyme that functions in photosynthesis The coenzyme that functions in photosynthesis is is NicotinamideadeninedinucleotidephosphateNicotinamideadeninedinucleotidephosphate
Ok, it is really 4 words, and we can call it Ok, it is really 4 words, and we can call it NADPNADP
NADP + 2H NADPHNADP + 2H NADPH22
PhotosynthesisPhotosynthesis
Divided into 2 stages, the Divided into 2 stages, the Light Reaction Light Reaction and and the the Dark ReactionDark Reaction
Balanced chemical equation:Balanced chemical equation: 6 CO6 CO22 + 12 H + 12 H22O + Light CO + Light C66HH1212OO6 6 + 6O+ 6O2 2 + 6H+ 6H22OO
DR DR LR LR DRDR LR LR DRDR
Light ReactionLight Reaction
Can only take place in the presence of light Can only take place in the presence of light energyenergy
Happens in the thylakoid disks Happens in the thylakoid disks Consists of 3 reactions that are happening at Consists of 3 reactions that are happening at
the same time and are interdependent.the same time and are interdependent.
1.1. Photosystem 1 (PS1)Photosystem 1 (PS1)
2.2. Photosystem 2 (PS2)Photosystem 2 (PS2)
3.3. PhotolysisPhotolysis
Products of the Light ReactionProducts of the Light Reaction
The “Light Reaction” is considered the The “Light Reaction” is considered the power phasepower phase
The products of the Light Reaction areThe products of the Light Reaction are
1.1. ATP – provide a source of energy for the ATP – provide a source of energy for the Dark Reaction Dark Reaction (and some phosphates)(and some phosphates)
2.2. NADPHNADPH2 2 – provide H for the – provide H for the Dark Reaction Dark Reaction
(and a little energy)(and a little energy)
Photosystem 1Photosystem 1
Chlorophyll of PS1 absorbs energy and Chlorophyll of PS1 absorbs energy and becomes “excited” (EM spectrum?)becomes “excited” (EM spectrum?)
Chlorophyll loses 4 electronsChlorophyll loses 4 electrons This creates a problem: “chlorophyll ain’t This creates a problem: “chlorophyll ain’t
chlorophyll no more”chlorophyll no more” PS2 to the rescue!PS2 to the rescue!
Photosystem 2Photosystem 2
Chlorophyll of PS2 absorbs light energyChlorophyll of PS2 absorbs light energy Chlorophyll loses 4 electronsChlorophyll loses 4 electrons These electrons move along an ETC and replace the These electrons move along an ETC and replace the
electrons lost in PS1electrons lost in PS1 As they move along the ETC, energy is given off and As they move along the ETC, energy is given off and
used to produce ATP.used to produce ATP. For every pair of electrons moved, enough energy is For every pair of electrons moved, enough energy is
released to synthesize 1 ATP, therefore …. released to synthesize 1 ATP, therefore …. One problem solved…….One problem solved……. One problem created…… One problem created……
PS2 continuedPS2 continued
Chlorophyll of PS1 has been restoredChlorophyll of PS1 has been restored
Chlorophyll of PS2 is missing electronsChlorophyll of PS2 is missing electrons
Have no fear!Have no fear!
Photolysis to the rescue!Photolysis to the rescue!
PhotolysisPhotolysis
- breakdown of water, in the presence of - breakdown of water, in the presence of sunlight.sunlight.
2 H2 H22O + sunlight = 4 Hydrogen atoms + 2 O + sunlight = 4 Hydrogen atoms + 2
oxygen atoms.oxygen atoms. 4 H separate into 4 electrons (-) and 4 protons 4 H separate into 4 electrons (-) and 4 protons
(+)(+) 2 O join to form O2 O join to form O2 2 (atmospheric oxygen gas)(atmospheric oxygen gas)
What happens to the products of What happens to the products of Photolysis?Photolysis?
4 electrons – replace those lost from PS24 electrons – replace those lost from PS2 4 protons - join with the original electrons lost 4 protons - join with the original electrons lost
from PS1 to form 4 hydrogen atomsfrom PS1 to form 4 hydrogen atoms OO2 2 is released into the atmosphereis released into the atmosphere The 4 hydrogen atoms are picked up by the The 4 hydrogen atoms are picked up by the
coenzyme (hydrogen carrier) NADPcoenzyme (hydrogen carrier) NADP 2 NADP + 4 H = 2NADPH2 NADP + 4 H = 2NADPH22
2NADPH2NADPH2 2 carry hydrogen atoms to the carry hydrogen atoms to the Dark Dark ReactionReaction
How many ATP are produced in the How many ATP are produced in the Light Reaction?Light Reaction?
2 ATP come from the ETC2 ATP come from the ETC
A third ATP is produced when sunlight A third ATP is produced when sunlight provides the energy needed to attach a provides the energy needed to attach a phosphate to an ADP molecule…..this is phosphate to an ADP molecule…..this is calledcalled
PhotophosphorylationPhotophosphorylation
End products of the Light ReactionEnd products of the Light Reaction
2 NADPH2 NADPH2 2 – carry hydrogen atoms to the – carry hydrogen atoms to the Dark Dark
Reaction (and some energy)Reaction (and some energy)
3 ATP – provide energy for the 3 ATP – provide energy for the Dark Reaction Dark Reaction (and some phosphates)(and some phosphates)