After light has been absorbed by pigments it has to be turned into chemical energy which is stored in ATP(adenosine triphosphate)and
NADPH( nicotinamide adenine dinucleotide phosphate). During this process chlorophyll are grouped in clusters called photosystems.The
two different photosystems involved in photosynthesis are Photosystem I and Photosystem II. These are the five major steps
of the light reactions.
1.Light energy raises the electrons found in chlorophyll a to a higher en ergy level. The electrons then leave
the chlorophyll a molecules and since chlorophyll a lost it is called and oxidation reaction.
2.The electrons lost from chlorophyll a are accepted in a part of the thylakoid membrane called the primary electron
acceptor.
3.The primary electron acceptor donates electrons to the electron transport train.It is called the electron transport
chain because it transports electrons from one molecule to the next. When the molecules are moved they lose energy and
are used too move protons(H+) into the thylakoid.
4.Light is absorbed by photosystem I. Electrons move from chlorophyll a molecues in photosystem I to another primary
electron acceptor. These electrons are replaced by electrons from photosystem II.
The primary electron acceptor of photosystem I donates electrons to a different electron transport chain. This chain
brings electrons to the side of the electron by the stroma.
5.Electrons combine with a proton and NADP+. As a result NADP+ is reduced to NADPH
