Chloroplasts: What are, structure and function

Chloroplasts are organelles typical of eukaryotic photosintetizer cellsboth algae and upper plants. Classify within the subcellular organelles called plastids or plastics.

Now, where are chloroplasts? They are found in the mesophilic cells of the leaves, or In cells that have photosynthesize capacity. In parts of the plant where the light does not reach, such as the roots, there are no chloroplasts.

At smaller scale, chloroplasts are willing In the cell cytoplasmand are not always in the same form or number, but vary from plant to plant. The upper plants have 10 thousand chloroplasts per cell on average, and are oval or circular. Algae have only 1 to 2 chloroplasts, and can be shaped like a star, tape, among other peculiar forms.

We recommend you read this other article about the plant cell: what is, parts, characteristics and functions.

So that the chloroplast is functional needs each of its structures. The chloroplast parts are:

• External membrane: It delimits to the chloroplast from abroad, and is permeable to small molecules that pass through porinas.
• Internal membrane: It is waterproof and is selective because it has specific proteins for the passage of molecules, both in and out of the chloroplast. As we can see, it has two membranes, so chloroplast in general is known as a double membrane laminar system.
• Intermembranal compartment: It is located between both membranes. It is very narrow.
• TILACOIDS: They are hollow bags containing chlorophyll molecules, and other pigments that capture the light. In addition, they contain enzymes and proteins. They also have a membrane that delimits them. These tilacoids have inserts in the membrane to photosystems I and II, which are complex pigment-protein.
• Lumen: It is the space that forms within the tilacoid.
• Cochineal: They are batteries formed by several tilacoids, with a function of maximizing space. They go from 10 to 100 per chloroplast.
• Laminar stroma: They connect to the granas only by a segment and without being stacked.
• Stroma: It is the internal space that surrounds the tilacoids. It is formed by a solution full of enzymes. It also contains DNA, RNA and Ribosomas. It is a dense aqueous solution. It has a high pH.

The most important function of chloroplasts is that They carry out the photosynthesis of eukaryotic organismsprocess that is divided into two phases and each one is completed in a different part of the chloroplast.

In the tilacoid membrane the light reactions that depend on sunlight for Form ATP and NADPH. That is to say, light energy is transformed into chemical energy usable for the plant, what is called transduction. This is possible thanks to photosystems I and II. Photosystem I is rich in chlorophyll ay the photosystem II in chlorophyll B, which vary from one to another for a small change in its structure.

Remember that photosynthesis not only has light phase, but also dark. Here, the energy produced in the luminous phase is used to fix CO2 to produce glucose, using the Calvin cycle. This dark phase occurs in chloroplast stroma. The manufactured glucose is a type of sugar, which will be used by the plant, or transferred to primary consumers who eat said plant.

In addition to carrying out photosynthesis there are other important activities that occur in chloroplast, especially aimed at its operation to be able to photosynthesize. Such are:

• Ion and metabolites regulation: It happens in the membrane, which has proteins that modulate the entry of metabolites and ions necessary for photosynthesis, and to transport the cell to the products that resulted from said process.
• RNA and protein synthesis: These components necessary for chloroplast are manufactured in part by their DNA, but also by the core of the plant cell. For this reason, it is said that chloroplast DNA has partial genetic autonomy, because nuclear DNA depends.
• Synthesize pigments: Chloroplast manufactures its own pigments, which are the essential part to capture the light.
• Accumulate reserve substances: It can accumulate substances that will be used later by the cell, such as starch.

At this point you have learned more about what chloroplasts, their structure and function are. As they are basic for the process of photosynthesis, we encourage you to learn more about it with these articles on photosynthesis: what is, phases and importance and the difference between photosynthesis and breathing of plants.

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