Biology II ( Assignment ) August 03,2010

1.Draw The Non-Cyclic And Cyclic Flow Of Electrons In Light Reactions.

NON - CYCLIC



1. Light strikes photosystem II and the energy is absorbed and passed along until it reaches P680 chlorophyll.
2. The excited electron is passed to the primary electron acceptor. Photolysis in the thylakoid takes the electrons from water and passes them back to 680, to replace electrons passed to the primary electron acceptor. (The Hydrogen ions are used up, but the oxygen is not, the oxygen atoms join together to form O2, which is released as a waste product - yay for us!)
3. The electrons is then passed to photosystem I via the electron transport chain
4. This process produces ATP which is used later in the Calvin Cycle
5, 6. P700 chlorophyll then uses light to excite the electron to its own primary acceptor
7. The electron is sent down another chain to create NADPH (note, its not NADH, though it is similar, the P stands for photosynthesis)
8. The NADPH is then used later in the Calvin Cycle.

*the P680 and P700 refer to the wavelength of light absorbed by the pigments
[color=blue]

CYCLIC
[/size]
*A Key difference between the cyclic and noncyclic is that in the noncyclic pathway, the electrons taken from chlorophyll a are not recycled back down to the ground state, the electrons end up on NADPH.
*The cyclic pathway only uses photosystem I
*The electrons used in the cyclic pathway are excited, pass down the chain (creating ATP) and then land back on P700 to be used again - See, its a CYCLE
* Neither oxygen nor NADPH are produced in these reactions.



2.What Are The Events Of Calvin Cycle ?

CLICK HERE


3.Draw The Diagram Of Calvin Cycle.





MORE ABOUT PHOTOSYNTESIS

CALVIN CYCLE OR "DARK REACTIONS"
( PHOTOSYNTHESIS )