Chloroplast: Definition, Structure, Function

Chloroplast: Definition, Structure, Funcution


The Chloroplast Is An Internal Organ Found Mostly In The Organism.


  1. Chloroplast Is First Identified By Engelmann In Spirogyra.
  2. It Is The Green Pigment Found In All Plant Cells.
  3. Chloroplast Provides Food For Plants.
  4. Chloroplast Was First Discovered By Schimper (1864).


It Consists Of The Pigment Like Chlorophyll And Is Responsible For Photosynthesis.


Chloroplast Contains Protein, Lipid And Chlorophyll.

It Contains-

Protein- 20-30%


Chlorophyll- 4-5%

Nuclic Acid- 2-3%



Image source:- Google By nature
  • It Is A Double Membrane Structure.
  • It Is Bounded By Two Membrane Outer Membrane & Inner Membrane.
  • In Their Grana, Stroma, And Thylakoids Are Present.
  • Each Granum Consist Of A Disc Called Thylakoid.
  • The Inner Membrane Is A Gelatinous Matrix Called Stroma.
  • Chloroplast May Be Spherical Ovoid Or Disc-Shaped.
  • There Is 20 To 40 Chloroplast In Each Cell.
  • In Higher Plants Its Number Is Large.
  • In Some Cells, There Is Only One Chloroplast.


Thylakoids Contain The Chlorophyll Pigments.

The Stroma Contains The Enzymes Required For The Synthesis Of Carbohydrates And Proteins.


  • The Chloroplast Is The Center Of the Synthesis And Metabolism Of Carbohydrates.
  • Light Energy Is Converted Into Chemical Energy.
  • Granum Is The Site Where Sunlight Energy Is Trapped.
  • Synthesis Of Organic Acid.
  • Oxygen Supply.
  • Food Supply

Others Components


Plastids Are Small Bodies Found In The Cytoplasm Of Most Plant Cells. They Are Absent In Bacteria, Certain Fungi And Algae.

There Are 3 Main Groups Of Plastid.





Amyloplast Is Non-Pigmented Organelles Found In Some Plants Cells. They Are Responsible For The Synthesis And Storage Of Starch Granules.


These Are Colored Plastids.

Responsible For The Orange And Yellow Color Of Fruits, Flower.


It Is Found In Algae, Leaves And Other Green Plant Organs.


Chlorophyll Is A Green Pigment Found In Algae And Plants In Cyanobacteria And Chloroplast.

Chlorophyll A (C55H72O5M4Mg)

Chlorophyll B (C55H70O6N4Mg)

Chlorophyll C (C35H32O5N4Mg)

Chlorophyll D (C55H70O6N4Mg)

Chlorophyll E

Xanthophyll (C40H50O2)

Carotin (C40H56)

Chlorophyll A

It Is A Bluish-Green Color And It Absorbs Red And Blue Light.

It Is A Universal Pigment Act As Both Antenna Molecule & PPRC.

Chlorophyll B

It Has An Aldehyde Group At 3rd Carbon Of Second Pyrol Ring.

It Can Be Found In Green Algae.

Chlorophyll B Mainly Absorb Blue & Orange And Reflect Yellow Light.

Chlorophyll C

It Is Present In A Member Of Brown Algae.

It As No Tail. It Absorbs Blue Light And Orange Color.

It Reflects A Yellow Color.

Chlorophyll D

It Is Present In A Member Of Red Algae.

It Contains Both Head And Tail.

It Has Formyl Group At 2 Carbon Of The First Pyroll Ring Where Venyl Group Present In Chlorophyll A.

Chlorophyll E

Its Formula And Structure Are Not Known.

It Is Found In Members Of Xenthophycea. (Yellow-Green Algae)


It Is Only Derivative Of Carotene.

It Is Yellow In Color And Absorbs Mainly Blue Light.


Obtain the First Time In Carrot.

Located In Chloroplast And Chromatoplast.

Soluble In The Organic Solvent And Insoluble In Water.


  1. Photosynthesis Occurs In Chloroplast Thylakoid Membrane.
  2. It Is The Ultimate Source Of Metabolic Energy For All Biological System.
  3. Photosynthesis Includes Light Reaction And Dark Reaction Take Place In Grana Of The Thylakoid Membrane And Dark Reaction Take Place In Stroma.

Each Photosystem Consists Of Two Complexes.

1.Core Complex

2.Antennae Complex


1. It Is Provides Food For Plant.

2. It Is The Green Pigment Necessary For Plant And Other Photosynthesis.


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