Scientists know what plant pigments are - green and purple, yellow and red. Plant pigments are called organic molecules that are found in tissues, cells of a plant organism - it is thanks to such inclusions that they acquire color. In nature, chlorophyll is found more often than others, which is present in the body of any higher plant. Orange, reddish tone, yellowish shades are provided by carotenoids.
And more details?
Plant pigments are found in chromo-, chloroplasts. In total, modern science knows several hundred varieties of compounds of this type. An impressive percentage of all discovered molecules are required for photosynthesis. As tests have shown, pigments are sources of retinol. Pink and red shades, variations of brown and bluish colors are provided by the presence of anthocyanins. Such pigments are observed in plant cell sap. When the days get shorter during the cold season,pigments react with other compounds present in the body of the plant, causing the color of the previously green parts to change. The foliage of the trees becomes bright and colorful - the same autumn we are used to.
The most famous
Perhaps almost every high school student knows about chlorophyll, a plant pigment necessary for photosynthesis. Due to this compound, a representative of the plant world can absorb the light of the sun. However, on our planet, not only plants cannot exist without chlorophyll. As further studies have shown, this compound is absolutely indispensable for humanity, as it provides natural protection against cancer processes. It has been proven that the pigment inhibits carcinogens and guarantees DNA protection from mutations under the influence of toxic compounds.
Chlorophyll is the green pigment of plants, chemically representing a molecule. It is localized in chloroplasts. It is due to such a molecule that these areas are colored green. In its structure, the molecule is a porphyrin ring. Due to this specificity, the pigment resembles heme, which is a structural element of hemoglobin. The key difference is in the central atom: in heme, iron takes its place; for chlorophyll, magnesium is the most significant. Scientists first discovered this fact in 1930. The event occurred 15 years after Willstatter discovered the substance.
Chemistry and Biology
First, scientists found that the green pigment in plants comes in two varieties, which were given names for twothe first letters of the Latin alphabet. The difference between the varieties, although small, is still there, and is most noticeable in the analysis of side chains. For the first variety, CH3 plays their role, for the second type - CHO. Both forms of chlorophyll belong to the class of active photoreceptors. Due to them, the plant can absorb the energy component of solar radiation. Subsequently, three more types of chlorophyll were identified.
In science, the green pigment in plants is called chlorophyll. Investigating the differences between the two main varieties of this molecule inherent in higher vegetation, it was found that the wavelengths that can be absorbed by the pigment are somewhat different for types A and B. In fact, according to scientists, the varieties effectively complement each other, thereby providing the plant with the ability to maximize absorb the required amount of energy. Normally, the first type of chlorophyll is usually observed in a three times higher concentration than the second. Together they form a green plant pigment. Three other types are found only in ancient forms of vegetation.
Features of molecules
Studying the structure of plant pigments, it was found that both types of chlorophyll are fat-soluble molecules. Synthetic varieties created in laboratories dissolve in water, but their absorption in the body is possible only in the presence of fatty compounds. Plants use pigment to generate energy for growth. In the diet of people, it is used for the purpose of recovery.
Chlorophyll, likehemoglobin can function normally and produce carbohydrates when connected to protein chains. Visually, the protein seems to be a formation without a clear system and structure, but it is actually correct, and that is why chlorophyll can stably maintain its optimal position.
Activity Features
Scientists, studying this main pigment of higher plants, found that it is found in all greens: the list includes vegetables, algae, bacteria. Chlorophyll is a completely natural compound. By nature, it has the qualities of a protector and prevents the transformation, mutation of DNA under the influence of toxic compounds. Special research work was organized in the Indian Botanical Garden at the Research Institute. As scientists have discovered, chlorophyll obtained from fresh herbs can protect against toxic compounds, pathological bacteria, and also calms the activity of inflammation.
Chlorophyll is short-lived. These molecules are very fragile. The sun's rays lead to the death of the pigment, but the green leaf is able to generate new and new molecules that replace those who have served their comrades. In the autumn season, chlorophyll is no longer produced, so the foliage loses its color. Other pigments come to the fore, previously hidden from the eyes of an external observer.
There is no limit to variety
The variety of plant pigments known to modern researchers is exceptionally large. From year to year, scientists discover more and more new molecules. Relatively recently conductedstudies have made it possible to add three more types to the two varieties of chlorophyll mentioned above: C, C1, E. However, type A is still considered the most important. But carotenoids are even more diverse. This class of pigments is well known to science - it is due to them that carrot roots, many vegetables, citrus fruits, and other gifts of the plant world acquire shades. Additional tests have shown that canaries have yellow feathers due to carotenoids. They also give color to the egg yolk. Due to the abundance of carotenoids, Asian residents have a peculiar skin tone.
Neither man nor representatives of the animal world have such features of biochemistry that would allow the production of carotenoids. These substances appear on the basis of vitamin A. This is proved by observations on plant pigments: if the chicken did not receive vegetation with food, the egg yolks will be of a very weak shade. If a canary has been fed a large amount of food enriched with red carotenoids, its feathers will take on a bright shade of red.
Curious Features: Carotenoids
The yellow pigment in plants is called carotene. Scientists have found that xanthophylls provide a red tint. The number of representatives of these two types known to the scientific community is constantly increasing. In 1947, scientists knew about seven dozen carotenoids, and by 1970 there were already more than two hundred. To some extent, this is akin to the progress of knowledge in the field of physics: first they knew about atoms, then electrons and protons, and subsequently revealedeven smaller particles, for the designation of which only letters are used. Is it possible to speak about elementary particles? As the tests of physicists have shown, it is too early to use such a term - science has not yet been developed to the extent that it was possible to find them, if any. A similar situation has developed with pigments - every year new species and types are discovered, and biologists are only surprised, unable to explain the many-sided nature.
About Functions
Scientists involved in the pigments of higher plants cannot yet explain why and why nature has provided such a wide variety of pigment molecules. The functionality of some individual varieties has been revealed. It has been proven that carotene is necessary to ensure the safety of chlorophyll molecules from oxidation. The protection mechanism is due to the features of singlet oxygen, which is formed during the photosynthesis reaction as an additional product. This compound is highly aggressive.
Another feature of the yellow pigment in plant cells is its ability to increase the wavelength interval required for the photosynthesis process. At the moment, such a function has not been proven exactly, but a lot of research has been done to suggest that the final proof of the hypothesis is not far off. The rays that the green plant pigment cannot absorb are absorbed by the yellow pigment molecules. The energy is then directed to chlorophyll for further transformation.
Pigments: so different
Except for somevarieties of carotenoids, pigments called aurones, chalcones have a yellow color. Their chemical structure is in many ways similar to flavones. Such pigments do not occur very often in nature. They were found in leaflets, inflorescences of oxalis and snapdragons, they provide the color of coreopsis. Such pigments do not tolerate tobacco smoke. If you fumigate a plant with a cigarette, it will immediately turn red. Biological synthesis occurring in plant cells with the participation of chalcones leads to the generation of flavonols, flavones, aurones.
Both animals and plants have melanin. This pigment provides a brown tint to the hair, it is thanks to it that the curls can turn black. If the cells do not contain melanin, representatives of the animal world become albinos. In plants, the pigment is found in the skin of red grapes and in some inflorescences in the petals.
Blue and more
Vegetation gets its blue tint thanks to phytochrome. It is a protein plant pigment responsible for controlling flowering. It regulates seed germination. It is known that phytochrome can accelerate the flowering of some representatives of the plant world, while others have the opposite process of slowing down. To some extent, it can be compared with a clock, but biological. At the moment, scientists do not yet know all the specifics of the mechanism of action of the pigment. It was found that the structure of this molecule is adjusted by time of day and light, transmitting information about the level of light in the environment to the plant.
Blue pigment inplants - anthocyanin. However, there are several varieties. Anthocyanins not only give a blue color, but also pink, they also explain the red and lilac colors, sometimes dark, rich purple. Active generation of anthocyanins in plant cells is observed when the ambient temperature drops, the generation of chlorophyll stops. The color of the foliage changes from green to red, red, blue. Thanks to anthocyanins, roses and poppies have bright scarlet flowers. The same pigment explains the shades of geranium and cornflower inflorescences. Thanks to the blue variety of anthocyanin, bluebells have their delicate color. Certain varieties of this type of pigment are observed in grapes, red cabbage. Anthocyanins provide coloring of sloes, plums.
Bright and dark
Known yellow pigment, which scientists called anthochlor. It was found in the skin of primrose petals. Anthochlor is found in primroses, ram inflorescences. They are rich in poppies of yellow varieties and dahlias. This pigment gives a pleasant color to toadflax inflorescences, lemon fruits. It has been identified in some other plants.
Anthofein is relatively rare in nature. This is a dark pigment. Thanks to him, specific spots appear on the corolla of some legumes.
All bright pigments are conceived by nature for the specific color of representatives of the plant world. Thanks to this coloring, the plant attracts birds and animals. This ensures the spread of seeds.
About cells and structure
Trying to determinehow strongly the color of plants depends on pigments, how these molecules are arranged, why the whole process of pigmentation is necessary, scientists have discovered that plastids are present in the plant body. This is the name given to small bodies that may be colored, but are also colorless. Such little bodies are only and exclusively among representatives of the plant world. All plastids were divided into chloroplasts with a green tint, chromoplasts stained in different variations of the red spectrum (including yellow and transitional shades), and leucoplasts. The latter do not have any shades.
Normally, a plant cell contains one variety of plastids. Experiments have shown the ability of these bodies to transform from type to type. Chloroplasts are found in all green-stained plant organs. Leukoplasts are more often observed in parts hidden from the direct rays of the sun. There are many of them in rhizomes, they are found in tubers, sieve particles of some types of plants. Chromoplasts are typical for petals, ripe fruits. Thylakoid membranes are enriched in chlorophyll and carotenoids. Leucoplasts do not contain pigment molecules, but can be a location for synthesis processes, accumulation of nutrient compounds - proteins, starch, occasionally fats.
Reactions and transformations
Studying the photosynthetic pigments of higher plants, scientists have found that chromoplasts are colored red, due to the presence of carotenoids. It is generally accepted that chromoplasts are the final step in the development of plastids. They probably appear during the transformation of leuko-, chloroplasts when they age. Largelythe presence of such molecules determines the color of foliage in autumn, as well as bright, eye-pleasing flowers and fruits. Carotenoids are produced by algae, plant plankton, and plants. They can be generated by some bacteria, fungi. Carotenoids are responsible for the color of living representatives of the plant world. Some animals have systems of biochemistry, due to which carotenoids are transformed into other molecules. The feedstock for such a reaction is obtained from food.
According to observations of pink flamingos, these birds collect and filter spirulina and some other algae to obtain a yellow pigment, from which canthaxanthin, astaxanthin then appear. It is these molecules that give bird plumage such a beautiful color. Many fish and birds, crayfish and insects have a bright color due to carotenoids, which are obtained from the diet. Beta-carotene is transformed into some vitamins that are used for the benefit of a person - they protect the eyes from the effects of ultraviolet radiation.
Red and green
Speaking of the photosynthetic pigments of higher plants, it should be noted that they can absorb photons of light waves. It is noted that this applies only to the part of the spectrum visible to the human eye, that is, for a wavelength in the range of 400-700 nm. Plant particles can absorb only quanta that have sufficient energy reserves for the photosynthesis reaction. The absorption is solely the responsibility of the pigments. Scientists have studied the oldest forms of life in the plant world - bacteria, algae. It has been established that they contain different compounds that can accept light in the visible spectrum. Some species can receive light waves of radiation that is not perceived by the human eye - from a block near infrared. In addition to chlorophylls, such functionality is assigned by nature to bacteriorhodopsin, bacteriochlorophylls. Studies have shown the importance for the reactions of synthesis of phycobilins, carotenoids.
The diversity of plant photosynthetic pigments differs from group to group. Much is determined by the conditions in which the form of life lives. Representatives of the higher plant world have a smaller variety of pigments than evolutionarily ancient varieties.
What is it about?
Studying the photosynthetic pigments of plants, we found that higher plant forms have only two varieties of chlorophyll (mentioned earlier A, B). Both of these types are porphyrins that have a magnesium atom. They are predominantly included in light-harvesting complexes that absorb light energy and direct it to reaction centers. The centers contain a relatively small percentage of the total chlorophyll of the first type present in the plant. Here the primary interactions characteristic of photosynthesis take place. Chlorophyll is accompanied by carotenoids: as scientists have found, there are usually five varieties of them, no more. These elements also collect light.
Being dissolved, chlorophylls, carotenoids are plant pigments that have narrow light absorption bands that are quite far apart from each other. Chlorophyll has the ability to most effectivelyabsorb blue waves, they can work with red ones, but they capture green light very weakly. Spectrum expansion and overlap is provided by chloroplasts isolated from the leaves of the plant without much difficulty. Chloroplast membranes differ from solutions, since the coloring components are combined with proteins, fats, react with each other, and energy migrates between collectors and accumulation centers. If we consider the light absorption spectrum of a leaf, it will turn out to be even more complex, smoothed than a single chloroplast.
Reflection and absorption
Studying the pigments of a plant leaf, scientists have found that a certain percentage of the light that hits the leaf is reflected. This phenomenon was divided into two varieties: mirror, diffuse. They say about the first if the surface is shiny, smooth. The reflection of the sheet is predominantly formed by the second type. Light seeps into the thickness, scatters, changes direction, since both in the outer layer and inside the sheet there are separating surfaces with different refractive indices. Similar effects are observed when light passes through cells. There is no strong absorption, the optical path is much greater than the thickness of the sheet, measured geometrically, and the sheet is able to absorb more light than the pigment extracted from it. Leaves also absorb much more energy than chloroplasts studied separately.
Because there are different plant pigments - red, green and so on - respectively, the absorption phenomenon is uneven. The sheet is able to perceive light of different wavelengths, but the efficiency of the process is excellent. The highest absorption capacity of green foliage is inherent in the violet block of the spectrum, red, blue and blue. The strength of absorption is practically not determined by how concentrated the chlorophylls are. This is due to the fact that the medium has a high scattering power. If pigments are observed in high concentration, absorption occurs near the surface.
