Light Dependent Reaction Example: Detailed Facts

Photosynthesis is an exclusive mechanism in which the photosynthetic organisms prepare their food for survival. They undergo complex processes and one of them is the light dependent reaction.

In this article, we will see the systemic reactions of the light dependent reaction example involved with respect to living beings

Before we enter into the process we need to know, what is the light dependent reaction?

The Light dependent reaction is the first or the primary stage of the photosynthesis in which the photosynthetic organism obtains the solar energy source or the light source from the sun, processes it and converts it into chemical energy and utilizes them as ATP-Adenosine triphosphate and NADPH- Nicotinamide Adenine Dinucleotide Phosphate for their survival.

The internal structures present inside the photosynthetic organisms aid in the conversion of the raw photosynthetic materials and produce the Adenosine triphosphate and Nicotinamide Adenine Dinucleotide Phosphate.

light dependent reaction example
Photosynthetic Organism
Image Credits- Wikimedia

The ATP or Adenosine triphosphate is the vital energy molecule.

The NADPH or the Nicotinamide Adenine Dinucleotide Phosphate is an electron donor to the organism which helps in the biosynthesis of all the cell components.

Image Credits- Pixabay

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What is the Light dependent reaction example?

Light dependent reaction is nothing but a reaction which happens with the presence of light that is the reaction depends on light- Sunlight.

The accurate light dependent reaction example is the process of photosynthesis which takes place in the region of the chloroplast called thylakoid .

There is a light independent reaction in the process of photosynthesis that takes place in the stroma of the organelle chloroplast.

This article completely focuses on the light dependent reaction example.

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Detailed explanation on Photosynthetic light dependent reaction example or the Light dependent reaction of photosynthesis:

  • The aim of the light dependent reaction in photosynthesis is to trap the solar energy from the sunlight and break or convert the water molecule (H2O) into ATP-Adenosine triphosphate and NADPH- Nicotinamide Adenine Dinucleotide Phosphate.
  • The ATP molecule –Adenosine triphosphate molecule and NADPH molecule- Nicotinamide Adenine Dinucleotide Phosphate molecule given out from the light dependent reaction process and is further utilized in the light independent reaction process.
  • Chlorophyll is a pigment present inside the chloroplast. This pigment, chlorophyll absorbs the sunlight.
  • The thylakoids in the chloroplast have few membranes called the thylakoid membranes which have a protein complex called the Photo System- I, Photo System- II.
  • This chlorophyll that absorbs the sunlight is stored in these two protein complexes- Photo System- I, Photo System- II.
  • When the sunlight falls on the region of the chloroplast that is present in the Photo System- II, the electrons get excited and travel towards the thylakoid membranes leaving the region of the chloroplast.
  • The excited electrons travel along the thylakoid membranes along with the range of carrier proteins which are usually called the electron transport chain.
  • The Photo system- II breaks the water molecule that is H2O splits to 2 hydrogen molecules and one oxygen molecule. The oxygen escapes as oxygen gas.
  • The hydrogen ion gets flooded in the lumen of the thylakoid from the above process thus as they pass through the enzyme ATP synthase which give the final phosphate molecule to ADP(Adenosine diPhosphate) making it ATP- ATP-Adenosine triphosphate.
  • Finally, the electron that comes from the photosystem II reaches to the photosystem I, which also has chlorophyll. The solar energy from the sun makes the electron excited again, providing enough energy to pass in between the membrane and towards the stroma.
  • This combines with a hydrogen ion from the split up water molecule and an NADP+ to manufacture the energy holding molecule NADPH.
  • ATP and NADPH then go towards stroma from the thylakoid, where the energy molecule is used to proceed with the process of the light-independent reactions.

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Image credits- Flickr

The image represents that the photosynthetic organisms procure the Carbon- di- oxide from air and water from the soil and utilize it for the photosynthesis.

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What is the cyclic light dependent reaction of photosynthesis?

The process by which the solar energy is trapped and transformed into a chemical energy so that the organisms utilize and survive is called photosynthesis.

The method that the photosynthesis process takes up can be cyclic or non cyclic. If it is cyclic phosphorylation, the flow of electrons will be in a unique manner that is they show up circular or a loop like flow and returns back to the Photosystem-1

So the vital ingredients or the elements required to perform the photosynthesis process are

  • Carbon- di- oxide
  • Water
  • Sunlight

Only certain organisms will have the capacity to undergo this photosynthesis, they are called the photosynthetic organisms.

These photosynthetic organisms procure the Carbon- di- oxide from air and water from the soil and utilize it for the photosynthesis.

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What is the Non cyclic light dependent reaction of photosynthesis?

In case of non cyclic phosphorylation it’s just the opposite of the cyclic phosphorylation one.

In non cyclic phosphorylation, the electrons excite and they do not return as both the photosystem (photosystem-1 and 2) are involved.

A Brief Account on what happens in the photosynthesis process:

  • The process of photosynthesis looks very simple but it involves many complex mechanisms.
  • The sunlight is utilized and the carbon- di- oxide in the air is trapped and gets converted to sugar (energy molecule).
  • The sunlight is utilized and the water from the soil is converted to oxygen.

The photosynthesis equation:

6CO2 + 6H2O → C6H12O6 + 6O2

Summary of the light dependent reaction process:

  • The ultimate goal is to convert the solar light energy to chemical energy.
  • The light dependent reaction process will be performed in the thylakoid of the chloroplast organelle.
  • The raw materials used is NADP+, Sunlight, H2O, ADP and the final products are NADPH, ATP, O2.
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