You plastos, also called plastids, are structures found in plant cells that represent one of the main differences between these cells and animal cells. They are organelles that have their own DNA and are capable of replicating themselves. It is believed that the plastids, as well as the mitochondria, are the results of symbiotic relationships.
These double-membrane organelles come in a variety of shapes and sizes. The plastids have a matrix that is named stroma, where a complex membrane system called the thylakoids. They are related to several functions, such as photosynthesis and the production of amino acids and fatty acids.
They can be classified according to the pigment they have or according to the substance they accumulate. In general, we can classify plastids into three groups:
- Chloroplasts;
- Chromoplasts;
- Leukoplasts.
You chloroplasts are the best known plastids, after all, they are the site of photosynthesis. Furthermore, they are related to the synthesis of amino acids and fatty acids. They are able to move inside the cell, positioning themselves in the best way to capture the light. They are characterized by the presence of chlorophyll in their interior, in addition to carotenoids. They are green plastids, as the carotenoids end up masked by chlorophyll. This plastid has a discoid shape and, in its matrix, it is possible to see the organization of the discoid thylakoids into piles. This organization is called
granum, and its set is called money. There are also thylakoids that interconnect these cells (stromal thylakoid), thus forming a large and complex network.Do not stop now... There's more after the advertising ;)
You chromoplasts are those that accumulate carotenoids and usually lack chlorophyll. Its color varies from yellow to red. Its main function is not to carry out photosynthesis, as the chloroplasts, being related mainly with the attraction of pollinators and dispersers, since they are found giving color to the petals and fruits.
You leukoplasts they have no pigment, their internal membrane system is not very elaborate, and they work by storing substances. Its name changes according to the substance that is found inside:
- Amyloplasts: accumulate starch;
- Proteinoplasts: They accumulate proteins;
- Elaioplasts or oleoplasts: They accumulate lipophilic substances.
All of the plastids mentioned can originate from colorless organelles with a matrix with few thylakoids, the so-called proplastids. Furthermore, plastids exhibit considerable ease in converting into different types. A chromoplast can be formed from a chloroplast, for example.
It can be seen, therefore, that the plastids have important functions for the plant. Without them, plants would be unable to carry out the photosynthesis process, making it impossible, for example, for their survival.
By Ma. Vanessa dos Santos
Would you like to reference this text in a school or academic work? Look:
SANTOS, Vanessa Sardinha dos. "Plastos"; Brazil School. Available in: https://brasilescola.uol.com.br/biologia/plastos.htm. Accessed on June 27, 2021.
