Light Dependent Reaction

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

In this article, we will look at the light-dependent response examples of systemic reactions involved in relation to living beings.

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

The light dependent reaction is the first or primary stage of photosynthesis in which a photosynthetic organism receives a solar energy source or light source from the sun, processes it and converts it into chemical energy and uses them to ATP-adenosine triphosphate and NADPH-nicotinamide adenine dinucleotide phosphatase for their survival.

RSI internal structures assist in the conversion of crude photosynthetic substances present inside photosynthetic organisms and produce adenosine triphosphate and nicotinamide adenine dinucleotide phosphate.

RSI ATP or adenosine triphosphate is the vital energy molecule.

RSI NADPH or nicotinamide adenine dinucleotide phosphate is an electron donor for the organism that helps in the biosynthesis of all cell components.

Light Dependent Reaction

What is a light dependent reaction example?

Light dependent reaction is nothing but a reaction that occurs with the presence of light i.e. the reaction depends on light- sunlight.

The precise example of a light dependent reaction is the process of photosynthesis that occurs in the region of the chloroplast called the thylakoid.

The process of photosynthesis has a different light independent reaction s that occurs in the stroma of the organelle chloroplast for each series.

This article focuses entirely on the light dependent reaction example

Photosynthetic light dependent reaction example or detailed description on light dependent reaction of photosynthesis:

  • The purpose of a light-dependent reaction in photosynthesis is to trap solar energy from sunlight and break down or convert the water molecule (H2O) into ATP-adenosine triphosphate and NADPH-nicotinamide adenine dinucleotide phosphate.
  • The ATP molecule – adenosine triphosphate molecule and the NADPH molecule – nicotinamide adenine dinucleotide phosphate are molecules given off from the light dependent reaction process and further used in the light independent reaction process.
  • Chlorophyll is a pigment present inside the chloroplast. This pigment, chlorophyll, absorbs sunlight.
  • Thylakoids in RSI chloroplasts are membranes called thylakoid membranes that contain a protein complex called photosystem- I, photosystem-II.
  • It is the chlorophyll that absorbs sunlight and is stored in these two protein complexes- photosystem-I, photosystem-II.
  • When sunlight falls on the region the electrons of the chloroplasts present in the photosystem-II get excited and leave the region of the chloroplast and travel towards the thylakoid membrane.
  • RSI excited electrons travel along a range of thylakoid membrane carrier proteins commonly referred to as the electron transport chain.
  • RSI PHOTO SYSTEM-II breaks down the water molecule which is H2O 2 splits into hydrogen molecules and one oxygen molecule . Oxygen is released as oxygen gas.
  • The RSI hydrogen ion is filled by the above process into the lumen of the thylakoid thus they undergo the enzyme ATP synthase which gives the final phosphate molecule ADP (adenosine diphosphate) making it ATP-ATP-adenosine triphosphate.
  • Finally, the electron that comes from photosystem II reaches photosystem I, which also contains chlorophyll. Solar energy from the Sun re-excites the electron, providing enough energy to pass between the membrane and towards the stroma.
  • This combines with a hydrogen ion from a water molecule and splits from a NADP+ to form the energy-carrying molecule NADPH.
  • ATP and NADPH then move from the thylakoid to the stroma, where the energy molecule is used to drive the process of light-independent reactions.

The image represents that photosynthetic organisms obtain carbon-di-oxide from the air and water from the soil and use it for photosynthesis.

What is the cyclic light dependent reaction of photosynthesis?

The process by which solar energy is trapped and converted into a chemical energy so that organisms can use and survive is called photosynthesis.

The process of photosynthesis can be cyclic or acyclic. If it is cyclic phosphorylation, the electrons will flow in a unique way that they show circular or a loop-like flow and return back to photosystem-1.

So the important element or elements required to carry out the photosynthesis process are

  • Carbon dioxide
  • Water
  • Sunlight

Only a few organisms will have the capability . After undergoing this photosynthesis, they are called photosynthetic organisms.

These photosynthetic organisms obtain carbon-di-oxide from the air and water from the soil and use it for photosynthesis.

What is the noncyclic light dependent reaction of photosynthesis?

In the case of noncyclic phosphorylation, it is the exact opposite of cyclic phosphorylation.

In noncyclic phosphorylation, electrons are excited and they do not retract because both photosystems are involved (photosystems 1 and 2).

A brief description on what happens in the photosynthesis process:

  • The process of photosynthesis looks very simple but it involves many complex mechanisms.
  • Sunlight is harnessed and carbon dioxide is trapped in the air and s. gets converted into ugar (energy molecule).
  • Sunlight is harnessed and water from the soil is converted into oxygen.

Photosynthesis Equation:

6CO 2 + 6H 2 O → C 6 H 12 O 6 + 6O 2

Summary of the light dependent reaction process:

  • RSI sole purpose is to convert solar light energy to chemical energy.
  • The light-dependent reaction will be performed in the process of thylakoid chloroplast organelles.
  • The raw material used is NADP+, sunlight, H2O, ADP and the final products are NADPH, ATP, O2 .
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