PHOTOSYNTHESIS C3 (Class presentations)

Mollie, Julian, and Christie

Light Reactions - Photosystem II

• Molecules involved in INPUT: Light, H2O
• No major enzymes
• Molecules in OUTPUT: 2 electrons, ATP
• Main objective of this stage/process
• To provide electrons for photosynthesis
• To produce ATP once it goes down the ETC
• Elaboration
• P680 molecules (described as wavelengths that represent when they absorb the most amount of light) are certain types of chlorophyll molecules that absorb energy in this process.
• When electrons that are trapped by P680 molecules get excited, they are released.

Light Reactions - Photosystem I

• Molecules involved in INPUT: light
• Major enzymes: NADPH (a coenzyme)
• Molecules in OUTPUT: 2 electrons, NADPH (energy-rich molecule)
• Main objective of this stage/process
• To move electrons into the Calvin Cycle to complete photosynthesis
• Elaboration
• If not enough ATP is produced, the electrons will move back into Photosystem I by the cyclic cycle
• If there is enough ATP, this starts the noncyclic cycle, which moves into the Calvin Cycle

Calvin Cycle - Phase I Carbon Fixation

• Molecules involved in INPUT: 6 molecules of CO2 per cycle, energy from NADPH, energy from ATP
• No major enzymes
• Molecules in OUTPUT: glucose, ADP, NADP+
• Main objectives of this stage/process
• To produce glucose
• Elaboration
• The Calvin Cycle is a light-independent reaction. This means that it does not directly need light to perform, but light must be present in order for it to perform (light comes in through phosphorylation)

http://www.biologycorner.com/resources/photosystem.jpg

^ Photosystem I and II ^

http://library.thinkquest.org/C004535/media/calvin_cycle.gif

^ The Calvin Cycle ^