Meaning of Chloroplasts

What are Chloroplasts:

chloroplasts are the cell organelles of plants and green algae that are responsible for carrying out photosynthesis.

chloroplasts found in eukaryotic organismsare found in large numbers and their sizes are variable, usually oval or spherical.


Likewise, chloroplasts fulfill different roles in plants, which is why they are evenly distributed in the cytoplasm of cells.

On the other hand, chloroplasts are characterized by having an envelope made up of two concentric membranes that have thylakoid vesicles, which contain photosynthetic pigments, such as chlorophyll, and other substances that transform light energy into chemical energy.

Therefore, the importance of chloroplasts lies in the transformation of light energy into chemical energy for vegetables, plants and green algae, that is, in photosynthesis.

See also Photosynthesis.

Chloroplast structure

The structure of chloroplasts is presented below.


The chloroplast has two membranes, one internal and one external.

  • outer membrane: It delimits the chloroplast, it is permeable, therefore it has transporter proteins, and it separates it from the cytoplasm.
  • inner membrane: it folds into the chloroplast and contains the thylakoids, whose appearance resembles a flattened sac.
  • Thylakodial membrane: It is located in the stroma and is where the thylakoids are grouped in the form of a grana.


The stroma is the aqueous part found in the inner membrane, which contains circular DNA molecules, RNA, ribosomes, lipids, cottonseed granules, among other substances. In the stroma the genetic process of the chloroplast and the reactions of photosynthesis are carried out.

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Also, within the stroma is the thylakoid membrane.


The thylakoids are flattened sacs bounded by the thylakoid membrane and can be found singly, overlapping, and interconnected. The thylakoids are arranged in a stacked fashion, and each of these stacks is called a grana.

It is in the thylakoids that the processes of plant photosynthesis are carried out.

Chloroplast function

The main function of chloroplasts is to carry out photosynthesis, a process in which the light phase that occurs in the thylakoid membrane (ATP and NADPH production) and the dark phase that occurs in the stroma (CO is fixed) are carried out.two through the Calvin Cycle and carbohydrates are formed).

In addition, chloroplasts carry out the biosynthesis of fatty acids through carbohydrates, ANDPH and ATP, and also reduce nitrates to synthesize amino acids.

See also Calvin Cycle.