PhotophosphorylationCarissa Fletcher

Photophosphorylation is the process of creating ATP using a Proton gradient created by the Energy gathered from sunlight.

The process of creating the Proton gradient resembles that of the electron transport chain of Respiration.

But since formation of this proton gradient is light-dependent, the process is called Photophosphorylation.

Chemiosmosis

Chemiosmosis - Chemiosmosis is the process of using Proton movement to join ADP and Pi.

This is accomplished by enzymes called ATP synthases.

As protons pass through this enzyme ADP and Pi are joined to make ATP.

The movement of the Protons through this enzyme provides the Energy needed to make

ATP Synthase

http://www.uic.edu/classes/bios/bios100/lectures/ps01.htm

Hydrogen pumping

http://www.uic.edu/classes/bios/bios100/lectures/ps01.htm

H+ ion gradient• Electrons leaving photosystem II are transferred transferred through a series of

molecules and ultimately end up transferred to to a molecule called plastoquinone (PQ).

• The PQ reacts with two hydrogen ions from the stroma and the two electrons from photosystem II to form PQH2.

2H+stroma + 2e- + PQ PQH2

• The PQH2 diffuses across the thylakoid membrane, passes the two electrons to the next electron carrier and releases the two hydrogen ions into the lumen.

PQH2 PQ + 2H+lumen + 2e-

• PQ can then diffuse back across the membrane to repeat the process. The net result of the cycle is to move two hydrogen ions from the stroma to the lumen

• THUS CREATING A GRADIENT

H+ ion gradient• Electrons leaving photosystem II are transferred transferred through a series of

molecules and ultimately end up transferred to to a molecule called plastoquinone (PQ).

• The PQ reacts with two hydrogen ions from the stroma and the two electrons from photosystem II to form PQH2.

2H+stroma + 2e- + PQ PQH2

• The PQH2 diffuses across the thylakoid membrane, passes the two electrons to the next electron carrier and releases the two hydrogen ions into the lumen.

PQH2 PQ + 2H+lumen + 2e-

• PQ can then diffuse back across the membrane to repeat the process. The net result of the cycle is to move two hydrogen ions from the stroma to the lumen

• THUS CREATING A GRADIENT