What are Chloroplasts?

Meaning of Chloroplasts

Chloroplasts are typical membranous plant organelles, also found in green algae, which are variable in size, but usually deal with the main organelles.

They have their own genome, that is, the genetic material that exists within the chloroplasts is different from the genetic material of the cell itself.

For this reason, it is believed that, like mitochondria, the origin of chloroplasts was due to endosymbiosis.

The endosymbiosis theory says that the appearance of some organelles occurred with the installation of a prokaryotic cell inside some type of primitive eukaryotic cell that plays an important role in its functioning.

This interaction would have become beneficial for both organisms, perpetuating itself throughout evolutionary history.

Basic Structure

Chloroplasts can have different shapes or sizes, however, the basic configuration of these structures is made up of an outer membrane, an inner membrane, the intermembrane space, stroma, and thylakoids.

The outer membrane separates the organelle from the intracellular environment and the inner membrane, in turn, delimits the functional space of the organelle, its interior.

This area that appears between the two membranes is called the intermembrane space and the set of these three regions is commonly called the envelope.

These membranes mentioned in the previous paragraph are biological membranes, so it is important to point out that they exert some type of control on the entry and exit of molecules.

Inside the inner membrane, a region is formed that contains many enzymes and proteins responsible for the chemical reactions of chloroplasts and various other molecules. This region is called the stroma.

In a mature chloroplast, the stroma is filled with several flattened vesicles known as thylakoids, and it is exactly within these discs that the chlorophyll molecules are found.

The thylakoids are arranged stacked on top of each other as if they were stacks of coins, so the set of these stacks is called money. Although an analogy is always made with the stack of coins, the name money has nothing to do with money.

This name is given to it because it is the plural of the Latin word granum, which means grain.


Vegetables, however complex they may be, are beings that are not looking for food.

Therefore, another strategy is needed to obtain nutrients and energy. Some of these nutrients and water are obtained through the root because they are present in the substrate that the vegetable is on.

However, the energy comes from glucose and it is not free or present in the soil. In this sense, the strategy used by these organisms is based on a process called photosynthesis.

Photosynthesis is, broadly speaking, a chemical reaction that occurs in cells using sunlight, carbon dioxide, and water, resulting in the production of glucose and the release of oxygen.

This process is characteristic of beings called autotrophs, that is, they “produce” their own food and it only occurs due to the chloroplast.

Finally, analyzing living organisms as a whole, the importance of the chloroplast can be seen. You see, it is due to the pigment present in the chloroplasts that plants are able to synthesize their own energy source.

By synthesizing this organic nutrient – ​​sugar – vegetables become the base of the food chain, being able to transfer energy to the other trophic levels of this network made up of producers, consumers and decomposers.

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