What are the important events and end products of the light reaction?

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Lifeeasy Authors · Answer 1

The light dependent reaction is the initial step of the process of photosynthesis, by which plants can store energy from sun light.

In this process light energy is converted to chemical energy in the form of energy reserving molecules ATP and NADPH.

It takes place in chloroplast, on the thylakoid membrane.

There are four major complexes in the membrane:

In presence of these complexes there are four major events takes place:

1. Transportation of electrons:

In the presence of sun light, electrons are excited and pass through the carriers from stroma to the intra thylakoid space.
By this it produces NADPH from NADP+.
The electron carriers are present in the thylakoid membrane, which are known as the major protein complexes of the membrane.

2. Splitting of water molecule:

Water molecule is splitted into oxygen, protons and electrons in the presence of manganese protein.
These splitted electrons are taken up by the photosystem II (PS II) that is absorbed at 700nm wavelength.
Due to this reaction protons are released into thylakoid space whereas oxygen released into the intra thylakoid space.

3. Proton pumping:

In this process of proton pumping, protons are diffused by special protein channels that are present in photosystem II (PS II).
Due to this transportation, formation of ATP initiates.

4. Formation of ATP

Formation of ATP takes place in the presence of ATP synthase enzyme.
Here, protons are back transported to the intra thylakoid space from the inner thylakoid space through ATP synthase.
This potential energy is used in the formation of ATP from ADP and inorganic molecule.

The end products of the light reaction are ATP and NADPH.