The electron pass through multiple electron carrier and during this proton are exported out of the thylakoid membrane into the lumen. The proton passed through ATP synthase and returned back into the stroma to generate ATP. The electron from PS-II is eventually been received by PS-I and been excited after absorbing photon from sun light to high energy state. The energy associated with these electron are used to generate NADPH in the stroma. Hence as a result of photosynthesis, solar energy is been trapped by photo synthesis apparatus to generate ATP and NADPH into the lumen. Both of them is now been used to run calvin cycle to assimilate environmental CO₂ to form sugar.

Figure 23.2: Different Steps of Photosynthesis.

5. Organelles of Vesicular Trafficking System: The main function of these organelles is to manage the distribution of material (food particles or proteins) through out the cells. 3 different organelles such as endoplasmic reticulum, golgi apparatus and lysosome co-ordinately work together to maintains vesicular transport of material across the cell (Figure 23.3). Eukaryotic cells takes up the solid material from outside the cells through a process called “endocytosis” where as uptake of liquid is through a process called as “pinocytosis”. Similarly material is secreted out of the cells through “exocytosis”. In addition, intravesicular system delivers protein synthesized in endoplasmic reticulum to different organelles.