ABSTRACT
Green plants use sunlight energy in natural photosynthesis. The sun emits radiation particularly in the wavelength range of 400-700 Å and energy range hν = 2 – 3 eV or hν = 200 – 300 kJ/mol. In this range, molecules can be electronically excited and covalent bonds broken or formed. In a biological organism, the energy take-up has to be done in a controlled way, without breaking the chemical bonds. The reaction center (RC) of photosynthetic organisms is part of a membrane protein, localized in the chloroplasts. Light harvesting takes place in the membrane proteins of the thylakoid membrane. Photosynthetic electron transport chains (ETC) have many similarities to the oxidative chains discussed in Chapter 11.
