The system through which electrons are transferred from one place to another is called electron transport system or ETS. It has 6 types of carriers.
1. Ferredoxin-Fd: Ferredoxin is an iron-sulfur protein. It accepts and transfers electrons.
2. Cytochrome-Cyt. : It is a protein with ferrous heme group. It accepts and transfers electrons.
3. Plastoquinone-PQ: It is a small mobile lipid molecule. It can move freely across the thylakoid membrane.
4. Pheophytin-Ph: It is converted to chlorophyll-a. It binds to the next carrier plastoquinone.
5. Plastocynin-PC: It is a small motile protein molecule containing copper. It circulates freely in thylakoid cells.
6. NADP/FAD-reductase: It is a flavoprotein. Its flavin part accepts electrons.