Chloroplasts of higher plants contain thylakoid membranes differentiated into several cylindri- cal granum stacks of appressed (stacked) membrane which are surrounded by non-appressed (unstacked) helically organized stroma thylakoids. The light reactions of photosynthesis are mediated by chlorophyll- protein complexes – Photosystem I (PSI) and Photosystem II (PSII) differentially embedded in granum and stroma membranes. Moreover, electron transport and conversion of light energy into ATP depend on cytochromes b6f and ATP synthase complexes.