Chloroplast is a green cell organelle

Chloroplast is one of the permanent cell organelles. It carries out the most important process of planetary importance - photosynthesis.

General plan of the structure of two-membrane organelles

Each organelle consists of a surface apparatus and internal contents. Chloroplasts and mitochondria are the structures of prokaryotic cell organisms that have a nucleus. The surface apparatus of these organelles consists of two membranes, between which there is free space. Spatially and anatomically, they are not connected with other structural parts of the cell and take part in the energy exchange. Mitochondria are organelles of most species of fungi, plants and animals. They serve for the synthesis of ATP - a substance that is a kind of reserve of energy cells. Chloroplast is also a two-membrane organelle that belongs to the plastid group.

Variety of plastids

In cells of living organisms there are three types of plastids. These are chloroplasts, chromoplasts and leukoplasts. They differ in color, structure and function. Chloroplast is a plastid of green color, containing pigment chlorophyll. Although often, thanks to the presence of other colorants, they can be brown and red. For example, in cells of various algae. At the same time, chromoplasts are always colorless. Their main function is the storage of nutrients. So, potato tubers contain starch. Chromoplasts are plastids that have carotenoid pigments. They impart color to different parts of plants. Brightly colored roots of carrots and beets, petals of flowers are a vivid example of this.

Plastids can be transformed. Initially, they arise from the cells of the educational tissue, which are small bubbles, surrounded by two membranes. In the presence of solar energy, they are converted into chloroplasts. With aging of leaves and stems, chlorophyll begins to break down. As a result, green plastids are converted into chromoplasts.

Here are a few more examples. Everyone saw that the leaves change their color in autumn. This is due to the fact that the chloroplasts turn into red, yellow, bard plastids. The same transformation occurs when the fruit ripens. In the light potato tubers become green: chlorophyll begins to form in leukoplasts. The final stage of development of plastids are chromoplasts, since they do not form other types of similar structures.

What are pigments?

The color, functions and structure of chloroplast are due to the presence of certain substances - pigments. By nature, they are organic compounds that stain different parts of the plant. Chlorophylls are the most common of them. They are found in cells of algae and higher plants. In nature, carotenoids also often occur. They are found in most known living things. In particular, in all plants, certain species of microorganisms, insects, fish and birds. In addition to the fact that they impart color to different organs, carotenoids are the main visual pigments, providing visual and color perception.

The structure of the membrane

Chloroplasts of plants have a double membrane. And the outside is smooth. And the inner forms outgrowths. They are directed inside the contents of the chloroplasts, which is called the stroma. With the internal membrane are connected and special structures - thylakoids. Visually they are flat single-membrane cisterns. They can be placed alone or collected in stacks of 5-20 pieces. They are called grains. Pigments are located on the structures of the thylakoids. The main ones are chlorophylls, and the auxiliary role is played by carotenoids. They are necessary for the realization of photosynthesis. The stroma also contains DNA and RNA molecules, starch grains and ribosomes.

Chloroplast functions

The main function of green plastids is the synthesis of organic substances from inorganic substances due to the energy of light. Its products are polysaccharide glucose and oxygen. Without this gas, the realization of the breathing of all beings on Earth will be impossible. So, photosynthesis is a vital process of planetary importance.

The structure of the chloroplast determines its other functions. Synthesis of ATP occurs on the membrane of these plastids. The significance of this process is the accumulation and storage of a certain amount of energy. This occurs during the onset of favorable environmental conditions: the availability of sufficient amounts of water, solar energy, food. During the course of vital processes, ATP splits with the release of a certain amount of energy. It is spent during the implementation of growth, development, movement, reproduction and other processes of life. Functions of chloroplasts consist also in the fact that in these plastids some lipids, membrane proteins and enzymes involved in the process of photosynthesis are synthesized.

The importance of the process of photosynthesis

Chloroplast is the link between the plant and the environment. As a result of photosynthesis, not only the formation of oxygen occurs, but also the cycling in nature of carbon, hydrogen, the maintenance of a constant composition of the atmosphere. This process limits the content of carbon dioxide, which prevents the occurrence of a greenhouse effect, overheating of the earth's surface and the death of many living beings on the planet. Plastids of chloroplasts, which are organelles of cells, carry out the most important functions, determining the existence of life on Earth.