Scientists know what plant pigments exist - green and purple, yellow and red. Organic molecules that are found in tissues, cells of a plant organism are called plant pigments - it is thanks to such inclusions that they acquire color. In nature, more often than others, chlorophyll is present in the body of any higher plant. Orange, reddish tone, yellowish shades provided by carotenoids.
And if more?
Plant pigments are in chromo-, chloroplasts. In total, modern science knows several hundred varieties of compounds of this type. An impressive percentage of all detected molecules is necessary for photosynthesis. As tests have shown, pigments are sources of retinol. Pink and red shades, variations of brown and bluish tones are provided by the presence of anthocyanins. Such pigments are observed in plant cell juice. When the days become shorter during the cooling period, the pigments react with other compounds present in the body of the plant, which makes the color of the previously green parts change. The foliage of the trees becomes bright and colorful - the very autumn that we are used to.
The most famous
Perhaps almost every high school student knows about chlorophyll - the 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 completely indispensable for humanity, as it provides natural protection against cancer processes. It has been proven that pigment inhibits carcinogens and guarantees DNA protection against mutations under the influence of toxic compounds.
Chlorophyll is a 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 in the central atom: in heme, iron takes its place, for chlorophyll the most significant is magnesium. Scientists first discovered this fact in 1930. The event occurred 15 years after the discovery of the substance by Willstatter.
Chemistry and biology
First, scientists found that the green pigment in plants is of two varieties, which were given the names by the first two 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, their role is played by CH3, for the second type - CHO. Both forms of chlorophyll belong to the class of active photoreceptors. At their expense, the plant can absorb the energy component of solar radiation. Subsequently, three more types of chlorophyll were identified.
In science, the green pigment of plants is called chlorophyll. Investigating the differences between the two main varieties of this molecule inherent in higher vegetation, it was found that the wavelength that can be absorbed by the pigment is somewhat different for types A and B. In fact, scientists believe, the varieties effectively complement each other, thereby providing the plant with the ability to maximize qualitatively absorb the necessary amounts of energy. Normally, usually the first type of chlorophyll is observed in three times higher concentration than the second. In total, they form a green plant pigment. Three other types were found only in ancient forms of vegetation.
Studying the structure of plant pigments, it was found that both varieties of chlorophyll are molecules soluble in fat. Synthetic varieties created in laboratories are soluble in water, but their absorption in the body is possible only in the presence of fatty compounds. Pigment is used by plants to produce energy that provides growth. In the diet of people, it is used to improve health.
Chlorophyll, as well as hemoglobin, can function normally and produce carbohydrates if 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.
Scientists, studying this basic pigment of higher plants, found that it is in all greens: the list includes vegetables, algae, bacteria. Chlorophyll is a completely natural compound. By nature, it has the properties of a tread and prevents the transformation, DNA mutation under the influence of toxic compounds. Special research works were organized in the Indian Botanical Garden at the Research Institute. As scientists were able to detect, chlorophyll obtained from fresh herbs can protect against poisonous compounds, pathological bacteria, and also soothes the activity of foci 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 their old comrades. In the fall 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 diversity
The variety of plant pigments known to modern researchers is exceptionally large. From year to year, scientists are discovering new molecules. More recently, studies have made it possible to add three more types to the two types of chlorophyll mentioned above: C, C1, E. However, the 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 they acquire shades of carrot root vegetables, many vegetables, fruits of citrus trees and other gifts of the plant world. As additional tests have shown, canaries have feathers painted yellow, precisely because of the carotenoids. They 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 biochemistry features 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 with food did not receive vegetation, the yolks of the eggs will be very faint. If the canary received a large amount of food enriched in red carotenoids, its feathers will acquire a bright shade of red.
Curious Features: Carotenoids
The yellow pigment of 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: at first they knew about atoms, then - about electrons and protons, and then even smaller particles were revealed, for which they are used only letters. Can we talk about elementary particles? As the tests of physicists have shown, it is too early to use such a term - science is not yet developed to the extent that it was possible to find them, if any. A similar situation has developed with pigments - from year to year they open up new species and types, and biologists are only surprised, unable to explain the many-sided nature.
Scientists involved in the pigments of higher plants can not yet explain why and why nature has provided such a wide variety of pigment molecules. The functionality of some individual varieties is revealed. It was proved that carotene is necessary to ensure the preservation of chlorophyll molecules from oxidation. The protection mechanism is due to the characteristics 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 necessary for the photosynthesis process. At the moment, such a function is not proved exactly, but a lot of research has been conducted to suggest that the final proof of the hypothesis is "just around the corner". Rays that the green plant pigment cannot absorb are absorbed by the yellow pigment molecules. Then the energy is sent to chlorophyll for further transformation.
What is chlorophyll?
Chlorophyll is a group of green pigments present in plants and other photosynthetic organisms. In fact, chlorophylls are the main pigments of photosynthetic organisms, including plants and algae. These pigments are able to capture the energy of light from sunlight and produce carbohydrates. Typically, there are several types of chlorophyll pigments in this family, such as chlorophyll a, b, c, and d.
Among several types of chlorophyll pigments, chlorophyll A and B are the most common pigments, which are mainly involved in photosynthesis. Chlorophylls absorb yellow and blue electromagnetic waves and reflect green. Consequently, they are visible to us in reflective green.
Structurally, the chlorophyll molecule contains a porphyrin ring, consisting of carbon, hydrogen, nitrogen and oxygen molecules surrounding the central metal ion, magnesium.
What are carotenoids?
The yellow, orange, and red colors that we see everywhere are due to pigments called carotenoids. These are chemical compounds that reflect these colors. In addition, there are two main types of carotenoids, namely, they are carotenes and xanthophylls. Carotenes are orange or yellow pigments, and xanthophylls are yellow pigments. The typical color of carrots is due to the beta-carotenes contained in it. On the other hand, the typical color of the tomato is due to lycopene, which is another carotenoid pigment.
Structurally, carotenoids contain two small six carbon rings and a long carbon chain. Therefore, they are not soluble in water. Instead, they are fat soluble. In addition, carotenoids play the role of additional pigments in photosynthetic organisms. Although carotenoids cannot directly absorb absorbed light through photosynthesis, they can transmit their light to chlorophylls and promote photosynthesis. Consequently, they are present in chloroplasts and even in cyanobacteria as well.
What are the similarities between chlorophyll and carotenoids?
- Chlorophylls and carotenoids are pigments.
- These are plant pigments.
- They are also present in chloroplasts.
- In addition, they are also present in cyanobacteria.
- In addition, both types of pigments can absorb light.
- In addition, both can absorb certain wavelengths of light and reflect certain other wavelengths that are visible to us.
What is the difference between chlorophyll and carotenoids?
Chlorophylls are plant pigments of green color, and carotenoids - from plant pigments of yellow to red. Therefore, this is the key difference between chlorophyll and carotenoids. In addition, there are several types of chlorophylls, chlorophyll a, b, c and d while there are only two types of carotenoids. These are carotenes and xanthophylls. Therefore, this is another difference between chlorophyll and carotenoids.
Moreover, both types of pigments can absorb light. But, unlike carotenoids, only chlorophylls can directly transmit light to the path of photosynthesis. In addition, there is also a structural difference between chlorophyll and carotenoids. Chlorophylls contain porphyrin rings in their structure, while carotenoids contain two small six carbon rings and a long carbon chain.
Summary - Chlorophyll vs Carotenoids
Chlorophylls and carotenoids are two types of plant pigments. The main difference between chlorophyll and carotenoids is reflective colors. Chlorophylls reflect the wavelength of green, therefore, visible in green, while carotenoids reflect wavelengths from yellow to red, therefore, visible in yellow, orange and red. In addition, chlorophylls are primary photosynthetic pigments that are directly involved in photosynthesis, while carotenoids are additional pigments that transfer absorbed light to chlorophylls due to the inability to transmit directly to the photosynthesis pathway. There are several types of chlorophylls, namely chlorophyll a, b, c and d, while there are two main types of carotenoids, namely carotenes and xanthophylls. Thus, this sums up the difference between chlorophyll and carotenoids.
Pigments: so different
In addition to some varieties of carotenoids, pigments called aurons, chalcones, are yellow. Their chemical structure is much like flavones. Such pigments in nature are not too common. They were found in leaflets, inflorescences of sour and snapdragons, they provide the color of coreopsis. Such pigments do not tolerate tobacco smoke. If you smoke a plant with a cigarette, it immediately turns red. Biological synthesis in plant cells involving chalcones leads to the generation of flavonols, flavones, aurons.
Both animals and plants have melanin. This pigment provides a brown shade of 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 was found in the peel of red grapes and in some inflorescences in the petals.
Blue and more
Vegetation receives a blue tint thanks to phytochrome. It is a protein plant pigment responsible for controlling flowering. It regulates the germination of a seed. It is known that phytochrome can accelerate the flowering of some representatives of the plant world, while others have the opposite process of deceleration. To some extent, it can be compared to a clock, but biological. At the moment, scientists do not yet know the specifics of the mechanism of action of the pigment. It was found that the structure of this molecule is corrected by the time of day and illumination, transmitting information about the level of light in the medium to the plant.
The blue pigment in plants is 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, saturated violet. Active generation of anthocyanins in plant cells is observed when the temperature of the surrounding space decreases, the generation of chlorophyll stops. The color of the foliage changes from green to red, red, blue. Thanks to anthocyanin, roses and poppies have bright scarlet flowers. The same pigment explains the shades of inflorescences of geraniums and cornflowers. Thanks to the blue variety of anthocyanin, the bells have a delicate color. Certain varieties of this type of pigment are found in grapes, red cabbage. Anthocyanins provide coloring of thorns, plums.
In summer, most trees have green leaves because they contain the chlorophyll pigment. This pigment is also used to convert sunlight to energy. In summer, chlorophyll is constantly in the leaves, but when it gets cold, plants stop producing chlorophyll, and it breaks down into other molecules. Trees can reuse nitrogen, which is in the chlorophyll molecule.
That's why leaves change color, and before they fall from the tree, important nutrients that can be reused are removed from the leaf. The time when the leaves begin to change color depends more on light than on temperature, so the leaves begin to change color at about the same time every year. When deciduous trees reach this light threshold, carbohydrates are transferred from leaves to branches, and new minerals no longer enter the foliage. Trees are preparing for separation from them.
Rainbow of Autumn Colors
The green color of chlorophyll is so strong that it masks any other pigment. The lack of green in the fall allows other colors to dominate. Leaves also contain pigments called carotenoids, xanthophylls are yellow (for example, in corn), and carotenes are orange (as in carrots). Anthocyanins (also found in blueberries and cherries) are pigments that are produced only in the fall, when cold days begin. Since at this stage the trees cut off most of the contacts with their leaves, the captured sugar in the leaf veins promotes the formation of anthocyanins, which are used to protect plants and create a reddish color.
However, in autumn, trees are not only yellow and red: they are brown, golden-bronze, golden yellow, purple-red, light brown, raspberry and orange-red. Different trees have different proportions of these pigments. The amount of chlorophyll remaining and the proportions of other pigments determine the color of the sheet. The combination of anthocyanins and chlorophyll gives a brown color, while anthocyanins and carotenoids create orange leaves.
Low temperatures, which are just above the freezing point, contribute to the formation of anthocyanin, which gives a bright red color. Early frost weakens colors because anthocyanin production ceases. But, for example, drought can lead to falling leaves without changing color.
There is a special mechanism for dropping leaves from trees. In the place of attachment of the leaf, a special layer of cells forms; they ultimately cut the tissue that attaches the leaf to the tree. Subsequently, the sheet can fall freely with a gust of wind, from gravity or rain. When the leaves begin to dry out, their chloroplasts completely collapse, changing their color to dirty brown.
Bright and dark
The yellow pigment is known, which scientists called antochlor. It was found in the skin of primrose petals. Antochlor found in primrose, ram inflorescences. They are rich in poppies of yellow varieties and dahlias. This pigment gives a pleasant color to the inflorescences of flax, lemon fruits. It is found in some other plants.
Antofein 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 a specific coloring of representatives of the plant world. Thanks to this coloring, the plant attracts birds, animals. This ensures the distribution of seeds.
About cells and structure
Trying to determine how much the color of plants depends on pigments, how these molecules are arranged, why the whole process of pigmentation is necessary, scientists found that plastids are present in the plant body. So called small bodies, which may have a color, but are also colorless. Such bodies are only and exclusively among representatives of the plant world. All plastids were divided into chloroplasts with a green tint, chromoplasts colored in different variations of the red spectrum (including yellow and transition shades), and leukoplasts. The latter are not inherent in 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 plant organs stained green. Leukoplasts are more often observed in parts hidden from direct sunlight. There are many of them in rhizomes, they are found in tubers, sieve particles of some types of plants. Chromoplasts are typical of petals of ripened fruits. Thylakoid membranes are enriched in chlorophyll and carotenoids. Leukoplasts do not contain pigment molecules, but can be the location of the processes of synthesis, accumulation of nutrient compounds - proteins, starch, and occasionally fat.
Reactions and Transformations
Studying the photosynthetic pigments of higher plants, scientists found that chromoplasts are colored red, 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. In many ways, the presence of such molecules determines the color of foliage in the fall, as well as bright, pleasing flowers and fruits. Carotenoids are produced by algae, plant plankton, and plants. Some bacteria and fungi can generate them. Carotenoids are responsible for coloring the living representatives of the plant world. Some animals have biochemistry systems, due to which carotenoids are transformed into other molecules. The feedstock for such a reaction is obtained with food.
As observations of pink flamingos have shown, these birds collect and filter spirulina and some other algae to produce yellow pigment, from which canthaxanthin and 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 with food. Beta-carotene is transformed into some vitamins that are used for the benefit of humans - they protect the eyes from ultraviolet radiation.
Red and green
Speaking about the photosynthetic pigments of higher plants, it should be noted that such can absorb light-wave quanta. 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 only absorb quanta, which have a sufficient energy reserve for the photosynthesis reaction. Responsibility for absorption rests solely with pigments. Scientists have studied the oldest life forms of the plant world - bacteria, algae. It was established that they have different compounds that can accept the light of the visible spectrum. Some varieties can receive light waves of radiation that is not perceived by the human eye - from a block close to infrared. In addition to chlorophylls, such functionality is naturally assigned to bacteriorhodopsin, bacteriochlorophylls. Studies have shown the importance for the synthesis of phycobilins, carotenoids.
The variety of photosynthetic plant pigments differs from group to group. Much is determined by the conditions in which the life form lives. Representatives of the higher plant world have less pigment diversity than evolutionarily ancient varieties.
What is it about?
Studying the photosynthetic pigments of plants, we found that in higher plant forms there are only two varieties of chlorophyll (the previously mentioned A, B). Both of these types are porphyrins, in which there is a magnesium atom. Mostly they enter light-harvesting complexes, which 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. Primary interactions characteristic of photosynthesis occur here. Chlorophylls are accompanied by carotenoids: they, as scientists have found, are usually observed in five varieties, no more. These elements also collect light.
Being dissolved, chlorophylls, carotenoids are plant pigments that have narrow light absorption bands that are quite distant from each other. Chlorophylls are inherently able to absorb blue waves as efficiently as possible, they can work with red ones, but they very poorly capture green light. The expansion of the spectrum and overlapping is ensured by chloroplasts secreted from the leaves of the plant without much difficulty. Chloroplast membranes differ from solutions, since the coloring components are connected with proteins, fats, react with each other, and energy migrates between the collectors and the accumulation centers. If we consider the spectrum of light absorption of the sheet, it will be even more complex, smoothed than a single chloroplast.
Reflection and absorption
Studying the pigments of a plant leaf, scientists found that a certain percentage of the light incident on the leaf is reflected. This phenomenon was divided into two varieties: mirror, diffuse. About the first they say if the surface is shiny, smooth. The reflection of the sheet is mainly formed by the second type. Light seeps into the thickness, scatters, changes direction, since there are separating surfaces with different refractive indices both in the outer layer and inside the sheet. Similar effects are observed when light passes through cells. There is no strong absorption, the optical path is much larger than the thickness of the sheet, measured geometrically, and the sheet is able to absorb more light than the pigment extracted from it. Leaves absorb much more energy and in comparison with separately studied chloroplasts.
Since there are different plant pigments — red, green, and others — 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 with respect to the violet block of the spectrum, red, blue and blue. The strength of absorption is practically not determined by how concentrated chlorophylls are. This is due to the fact that the environment is characterized by high scattering ability. If pigments are observed in high concentration, absorption occurs near the surface.