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PHOTON
The first stage of the Light Dependent Reaction is when the photon (or particle of light, typically from the sun) hits the plant -
ELECTRON JUMPS
Once the photon hits the plant it causes an electron in the the chloroplast (specifically the Thykaloid) to jump to a higher energy level -
ELECTRON PASSES THROUGH ETC
The energy that is created by the light hitting the electron and it jumping is captured as some of the electrons are forced to pass through the ETC (Electron Transport Chain), which is made up of proteins. -
ELECTRON ENERGY USED...
The energy that is relesed as electrons move through the ETC is used to pump H+ into the thylakoid disc. -
WHY DO WE PUMP H+ INTO THE CELL???
The cells pump the H+ into the thylakoid disc to create an electrochemical gradient (ACTIVE TRANSPORT). It is active transport because it goes against it's concentration gradient AND it's charge (the cell is positively charged so H+'s don't want to go in), This forces the H+'s to flow through the ATP Synthase (PASSIVE TRANSPORT) which creates ATP!!! (that will be used later on to make glucose) -
WHERE DO THE OTHER ELECTRONS GO?!
As you probably remember, not all the electrons flow through the ETC. Some of them break away from their original chlorophyll molecule and are caught by NADP+. This requires 2 electrons!!! Which of course, makes this molecule negative, thus attracting H+'s that are in the chloroplast. -
NADPH
Once the electrons and H+ bond with NADP you have... NADPH!! Which will be used later during THE CALVIN CYCLE!!! -
WHAT HAPPENS TO THE CHLOROPHYLL NOW IT'S MISSING ELECTRONS?!
The chlorophyll is still upset because it has lost several electrons that it can't get back. So, the plant uses water (H2O) takes electrons from the H's (making it H+) releases the oxygen from the plant and keeps the H+ in the cell to release through the ATP Synthase -
PHOTSYNTHESIS VIDEO
Here's a video on photosynthesis... Enjoy!
https://www.youtube.com/watch?v=sQK3Yr4Sc_k -
THE CALVIN CYCLE (or Light-Independent Reaction)
The Light Dependent reaction was only one half of Photosynthesis! Now the plant must use the NADPH and ATP to make glucose (sugar or energy) -
CARBON FIXATION
Carbon-Dioxide is taken out of the air (1 molecule at a time) and is attatched to a carbon based molecule (organic molecule). -
REDUCTION
ATP is added to the CO2 and organic molecule to give it energy, and NADPH adds electrons and hydrogens. -
WHER DOES THE NADP+ GO?
The NADP+ is cycled back to the light reactions to get electrons that have jumped due to photons -
MAKING GLUCOSE
This happens for every CO2 individually as it enters the cell until 3 of them have gone through. This all happens twice until you have C6H1206 (glucose) -
OVERALL CHEMICAL REACTION
6CO2+6H20--> C6H12O6+6O2
