Photosynthesis In Cytoplasm: 7 Facts You Should Know

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Plants manufacture oxygen and sugar-based energy through a process referred to as photosynthesis, which uses sunlight, water, and CO2 . Let us see more.

Photosynthesis take place within the chloroplast in the cytoplasm. Chloroplast is a double membranous body with complex internal membrane system organised into flattened sacs or thylakoids.

In higher plants, leaves are the main photosynthetic organ, although young stems of some herbaceous plant also act as an organ of photosynthesis.

Let us discuss if photosynthesis occur in cytoplasm, why and how it occurs in cytoplasm, its classifications and many other related facts in this article.

Does photosynthesis occur in cytoplasm?

Photosynthesis is the process by which plants capture photons and convert it into chemical energy locked in organic compound. Let us see if it occurs in cytoplasm or not.

Photosynthesis occurs in the chloroplast inside the cytoplasm of green plants. During the day, photosynthesis is carried out by chloroplasts. The photosynthetic cells use NADPH and ATP, the direct results of photosynthesis, to make a variety of chemical compounds.

Photosynthesis is the only natural process by which oxygen is liberated in the atmosphere to be used by other organism.

What part of photosynthesis occurs in cytoplasm?

The process of photosynthesis consist of two successive series of reaction- the light reaction and the dark reaction. Let us see which part of photosynthesis occurs in cytoplasm.

The second series of photosynthetic reaction that is the dark reaction or Blackman reaction takes place in the cytoplasm. In this reaction, carbon fixation occurs by a series of enzyme catalyzed steps.

C4 photosynthesis
Photosynthesis from Wikipedia

Molecules of ATP and NADPH2 produced in light reaction provide the energy needed to fix CO2 and to synthesize the carbohydrate.

Why does photosynthesis occur in the cytoplasm?

Photosynthesis occurs in the chloroplast within the cytoplasm in green plants and bacteria. Let us see why photosynthesis occurs in the cytoplasm.

Cytoplasm contains all essential components, that is enzymes and other chemicals and nutrients which are required for photosynthesis. Other than that cytoplsmic streaming is essential to optimize photosynthesis and for distributing nutrients through the cell.

How does photosynthesis occur in the cytoplasm?

Photosynthesis is light dependent oxidative reductive reaction in which chlorophyll oxidizes water into 02 forming NADPH+ and ATP which reduces CO2 into carbohydrate. Let us see more.

The process of photosynthesis is divided into two phases listed below –

  • Light or Hill’s reaction
  • Dark reaction or Blackman reaction

Light or Hill’s reaction:

The light reaction or photochemical reactions can be studied in the following heads:

  • Absorption of light energy by photosystems.
  • Photolysis of water and evolution of O2.
  • Reduction of NADP and formation of NADPH2
  • Photophosphorylation.

1. Absorption of light energy by photosystems:

There are two photosystems involved in photosynthesis. The function of the two photosystem is to trap light energy and convert it to the chemical energy i.e. ATP.

2. Photolysis of water and evolution of O2:

Splitting of water molecules occurs in this phase. Electrons are then released and oxygen is liberated at photosystem II (PS-II).

3. Reduction of NADP and formation of NADPH2:

Like PS-II, photosystem-I (PS-I) is excited on absorbing light and get oxidized. It transfer its electron to the electron acceptors, which in turns get reduced. NADP is reduced to NADPH2 by accepting electrons from PS-1 and H+ released during photolysis of water.

4. Photophosphorylation:

The process of ATP formation from ADP and Pi in the presence of sunlight in chloroplast is called photophosphorisation.

Dark reaction or Blackman reaction:

Molecules of ATP and NADPH2 produce in the light reaction provide the energy needed to fix CO2 and to synthesize carbohydrate in the dark reaction.

The various steps in the dark reaction may be described in the steps given below:

  • Fixation of CO2 / Carboxylation
  • Reduction of PGA
  • Synthesis of glucose
  • Regeneration of RuBP

1. Fixation of CO2 / Carboxylation:

In the first phase C02 is accepted by a 5- carbon compound, ribulose 1,5 bisphosphatase (RuBP) to form a 6 carbon intermediate. This intermediate compound then split up in presence of water into 2 molecule of phosphoglyceric acid (PGA).

2. Reduction of PGA:

PGA is immediately phosphorylated by taking phosphate from ATP produce during light reaction to diphosphoglyceric Acid(DPGA). The DPGA is reduced to phosphoglyceraldehyde( PGAld) by taking H2 from NADPH2 produce in photochemical reaction.

3. Synthesis of glucose:

The reactions occurs in this phase are as follows:

  1. One molecule of PGAld converted into Dihydroxy acetone phosphate(DHAP)
  2. PGAld and DHAP condense to for fructose bisphosphatase (FBP).
  3. FBP by dephoshphorylation produces fructose monophosphate(FMP)
  4. FMP by isomeric change converted to glucose monophosphate (GMP)
  5. GMP by dephoshphorylation is converted to glucose

4. Regeneration of RuBP:

For the continuous functioning of photosynthesis they must be regular supply of ATP, NADPH2 and also sufficient amount of RuBP which is the primary acceptor of CO2.

Where does photosynthesis occur in the cytoplasm?

Photosynthesis generally takes place in all the green parts of the plant body. Let us see where exactly it occurs inside the cytoplasm.

Photosynthesis occur in chloroplasts :- a kind of plastid, present in the cytoplsm. This plastid contains DNA, RNA, chlorophyll a, chlorophyll b etc. This type of plastids are present in the green parts of plants’ leaves.

What does cytoplasm do in photosynthesis?

Cytoplasm is essential for most of the reactions occuring inside the cell. Let us see in details the role of cytoplasm in photosynthesis.

The role of cytoplasm in photosynthesis is listed below.

  • All internal chemical reactions take place in the cytoplasm of the cell.
  • It offers a foundation for other organelles to function within the cell.
  • Cytoplasm provides the nutrients and enzymes necessary for the photosynthesis to occurs.
  • Chloroplast distribution for optimal light absorption for photosynthesis can be accomplished through cytoplasmic streaming.

Conclusion:

Chlorophyll and other pigments that are light-sensitive and absorb solar power are found in photosynthetic cells’ cytoplasm. Such cells have the capacity to rework solar energy into organic molecules with high energy content such as glucose, within the presence of CO2. Additionally, to power the global carbon cycle, these cells also generate a big amount of oxygen found in the Earth’s atmosphere.

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