Class 11 Photosynthesis

In the mesophyll cells of the leaves, there are a large number of chloroplasts. The membranes of granna inside chloroplast are the site for the light reaction while the dark reaction takes place in the matrix of the chloroplast ie stroma. 

In the light reaction, the light energy is absorbed by the pigment present in the antenna and funneled to special chlorophyll a molecules called Reaction Centre chlorophylls. 

There are two photo systems, PS1 and PS2. PS1 has a 700 NM absorbing chlorophyll called Chlorophyll a P700 molecule at its reaction centre, while PS2 has a P680 reaction centre that absorbs red light at 680 NM. After absorbing light, electrons are excited and transferred through PS2 and PS1 and finally to NAD forming NADH. 

Initially, in the dark reaction, carbon dioxide is added by the enzyme RuBisCO to a 5 carbon compound RuBP that is converted to two molecules of 3 carbon PGA. This is then converted to glucose. In this process, ATP and NADPH synthesized in the light reaction are utilised. 

Note: The above notes in the image(s) are taken from a personal notebook which was initially not intended to be shared online. Please excuse the rough handwriting and spelling errors, if any.