Most widespread in the 20th century. received the theory of biochemical evolution, proposed independently of each other by two outstanding scientists: the Russian chemist A. I. Oparin (1894-1980) and the English biologist John Haldane (1892-1964). This theory is based on the assumption that in the early stages of the development of the Earth there was a long period during which organic compounds were formed abiogenically. The source of energy for these processes was the ultraviolet radiation of the Sun, which at that time was not retained by the ozone layer, because there was no ozone or oxygen in the atmosphere of the ancient Earth. Synthesized organic compounds accumulated in the ancient ocean over tens of millions of years, forming the so-called “primary broth”, in which life probably arose in the form of the first primitive organisms - probionts.
This hypothesis was accepted by many scientists from different countries, and on its basis, in 1947, the English researcher John Desmond Bernal (1901-1971) formulated a modern theory of the origin of life on Earth, called the theory of biopoiesis.
Bernal identified three main stages of the origin of life: 1) abiogenic
the appearance of organic monomers; 2) formation of biological polymers; 3) formation of membrane structures and primary organisms (probionts). Let's take a closer look at what happened at each of these stages.
Abiogenic occurrence of organic monomers. Our planet originated about 4.6 billion years ago. The gradual densification of the planet was accompanied by the release of a huge amount of heat, radioactive compounds decayed, and a stream of hard ultraviolet radiation came from the Sun. After 500 million years, the Earth began to slowly cool. The formation of the earth's crust was accompanied by active volcanic activity. Gases accumulated in the primary atmosphere - products of reactions occurring in the bowels of the Earth: carbon dioxide (CO2), carbon monoxide (CO), ammonia (NH3), methane (CH4), hydrogen sulfide (H2S) and many others. Such gases are still released into the atmosphere during volcanic eruptions.
Water, constantly evaporating from the surface of the Earth, condensed in the upper layers of the atmosphere and again fell in the form of rain on the hot earth's surface. The gradual decrease in temperature led to downpours, accompanied by continuous thunderstorms, hitting the Earth. Reservoirs began to form on the earth's surface. Atmospheric gases and those substances that were washed out of the earth's crust dissolved in hot water. In the atmosphere, simple organic substances (formaldehyde, glycerin, some amino acids, urea, lactic acid, etc.) were formed from its components under the influence of frequent and strong electrical lightning discharges, powerful ultraviolet radiation, active volcanic activity, which was accompanied by emissions of radioactive compounds. Since there was no free oxygen in the atmosphere yet, these compounds, entering the waters of the primary ocean, were not oxidized and could accumulate, becoming more complex in structure and forming a concentrated “primary broth.” This went on for dozens
million years (Fig. 49).
In 1953, the American scientist Stanley Miller carried out an experiment in which he simulated the conditions that existed on Earth 4 billion years ago (Fig. 50). Instead of lightning discharges and ultraviolet radiation, the scientist used a high-voltage electrical discharge (60 thousand volts) as an energy source. The discharge of the discharge for several days corresponded in the amount of energy to a period of 50 million years on the ancient Earth. After the end of the experiment, organic compounds were discovered in the constructed installation: urea, lactic acid and some simple amino acids. 
Rice. 50. S. Miller’s experiment simulating the conditions of the Earth’s primary atmosphere
The essence of this theory is that biological evolution - i.e. The emergence, development and complication of various forms of living organisms was preceded by chemical evolution - a long period in the history of the Earth associated with the emergence, complication and improvement of the interaction between elementary units, the “building blocks” of which all living things are composed - organic molecules.
According to most scientists (primarily astronomers and geologists), the Earth was formed as a celestial body about 5 billion years ago by the condensation of particles of a gas and dust cloud rotating around the Sun.
During this period, the Earth was a hot ball, the surface temperature of which reached 4000-8000°C.
Gradually, due to the radiation of thermal energy into outer space, the Earth begins to cool. About 4 billion years ago, the Earth cooled so much that a solid crust formed on its surface; at the same time, light, gaseous substances erupt from its depths, rising upward and forming the primary atmosphere. The composition of the primary atmosphere was significantly different from the modern one. There was no free oxygen in the atmosphere of the ancient Earth, and its composition included hydrogen (H 2), methane (CH 4), ammonia (NH 3), water vapor (H 2 O), nitrogen (N 2), carbon monoxide and carbon dioxide ( CO and C0 2).
The absence of free oxygen in the atmosphere of the primordial Earth is an important prerequisite for the emergence of life, since oxygen easily oxidizes and thereby destroys organic compounds. Therefore, in the presence of free oxygen in the atmosphere, the accumulation of significant amounts of organic substances on the ancient Earth would have been impossible.
When the temperature of the primary atmosphere reaches 100°C, the synthesis of simple elements begins in it. organic molecules such as amino acids, nucleotides, fatty acids, etc.hot sugars, polyhydric alcohols, organic acids, etc. Energy for synthesis is supplied by lightning discharges, volcanic activity, hard cosmic radiation and, finally, ultraviolet radiation from the Sun, from which the Earth is not yet protected by an ozone shield, and scientists consider ultraviolet radiation to be the main source of energy for abiogenic (i.e. taking place without the participation of living organisms) synthesis of organic substances.
When the temperature of the primary atmosphere is below 100°C, the primary ocean is formed, synthesis begins simple organic molecules, and thencomplex biopolymers. The prototypes of living organisms are coacervate drops that appeared in the primordial ocean and formed an organic broth.Coacervate drops have some semblance of metabolism:
- can selectively absorb certain substances from solution and release their decay products into the environment and grow;
- upon reaching a certain size, they begin to “multiply”, budding small droplets, which, in turn, can grow and “bud”;
- in the process of mixing under the influence of waves and wind, they can become covered with a shell of lipids: a single shell, reminiscent of soap micelles (when a drop is lifted from the surface of water covered with a lipid layer once), or a double shell, reminiscent of a cell membrane (when a drop covered with a single-layer lipid membrane falls again, on the lipid film covering the surface of the reservoir).
The processes of the emergence of coacervate droplets, their growth and “budding”, as well as their “dressing” with a membrane of a lipid bilayer are easily simulated in laboratory conditions.
Thus, the processes of abiogenic synthesis of organic molecules were reproducibleed in model experiments.In 1828, the outstanding German chemist F. Wöhler synthesized an organic substance, urea, from an inorganic substance, ammonium cyanate.
In 1953 a young American researcher, a graduate student at the University of Chicago, Stanley Miller, reproduced in a glass flask with electrodes sealed into it the primary atmosphere of the Earth, which, according to scientists of that time, consisted of hydrogen methane CH 4, ammonia NH 3, and water vapor H 2 0. S. Miller passed electric discharges through this gas mixture for a week, simulating thunderstorms. At the end of the experiment, α-amino acids (glycine, alanine, asparagine, glutamine), organic acids (succinic, lactic, acetic, glycolic), y-hydroxybutyric acid and urea were found in the flask. By repeating the experiment, S. Miller was able to obtain individual nucleotides and short polynucleotide chains of five to six units.
J. Oro, by moderately heating a mixture of hydrogen, carbon, nitrogen, NH 3, H 2 O, obtained adenine, and by reacting an ammonia solution of urea with compounds arising from gases under the influence of electrical discharges, he obtained uracil.
L. Orgel (1980s) synthesized nucleotide chains six monomer units long in similar experiments.
S. Akabyuri obtained polymers of the simplest proteins.
Abiogenic synthesis of organic molecules can occur on Earth at the present time (for example, in the process of volcanic activity). At the same time, in volcanic emissions one can find not only hydrocyanic acid HCN, which is a precursor of amino acids and nucleotides, but also individual amino acids, nucleotides and even such complex organic substances as porphyrins. Abiogenic synthesis of organic substances is possible not only on Earth, but also in outer space. The simplest amino acids are found in meteorites and comets.
Theory abiogenic molecular evolution of life from inorganic substances was created by the Russian scientist A.I. Oparin (1924) and the English scientist J. Haldane (1929). According to natural scientists, the Earth appeared approximately 4.5–7 billion years ago. At first, the Earth was a dust cloud, the temperature of which fluctuated between 4000-8000°C. Gradually, during the cooling process, heavy elements began to be located in the center of our planet, and lighter ones - along the periphery.
It is assumed that the simplest living organisms on Earth appeared 3.5 billion years ago. Life is the result first chemical, and then biological evolution.
Protobionts are also not yet a complete form of life. It is assumed that they gradually acquired compounds similar to enzymes (coenzymes, enzymes themselves), and ATP, through abiogenic means.
Emergence of the cell (matrix synthesis)
The emergence of matrix synthesis as a result of mutual adaptation and fusion of the functions of proteins and nucleic acids played a major role in the transformation of protobionts into real cells.
Matrix synthesis is the biological synthesis of protein molecules based on information contained in nucleic acids.
With the emergence of the matrix synthesis process, chemical evolution gave way to biological evolution. The development of life now continued through biological evolution.
A.I. Oparin was the first to put forward the idea of experimentally studying the origin of life. Indeed, S. Miller (1953) created an experimental model of the primary conditions of the Earth. By influencing heated methane, ammonia, hydrogen and water vapor with an electric discharge, he synthesized amino acids such as asparagine, glycine, glutamine (in such a system, the gases imitated the atmosphere, the electric discharge imitated lightning; Fig. 57).
D. Oro, by heating hydrogen cyanide, ammonia and water, carried out the synthesis of adenine. Ribose and deoxy-ribose were synthesized by exposing methane, ammonia and water to ionizing radiation. The results of such experiments have been confirmed by numerous studies. In the process of evolution, monomers gradually turned into biological polymers (polypeptides, polynucleotides), which was also confirmed experimentally. Thus, in the experiments of S. Fox, proteinoids (protein-like substances) were synthesized by heating a mixture of amino acids. Subsequently, polymers of nucleotides were synthesized in experiments.
Compounds similar to coacervates were synthesized experimentally and thoroughly studied by A.I. Oparin and his students. Material from the site
However, it was unknown which came first in the biochemical evolution of life: proteins or nucleic acids. According to the theory of A.I. Oparin, protein molecules appeared first. Proponents of the genetic hypothesis, on the contrary, believed that nucleic acids arose first. This assumption was put forward in 1929 by G. Miller. Laboratory studies have proven the possibility of replication of nucleic acids without the influence of enzymes. According to scientists, the primary ribosomes consisted only of RNA, and the ability to synthesize protein could have appeared later. Later, new data were obtained confirming this assumption. Replication of ribonucleic acid without the participation of enzymes, reverse transcription, i.e. the possibility of DNA synthesis based on RNA - all this is evidence of the genetic hypothesis.
Evolution of life on Earth
The problem of the origin of life on Earth is one of the greatest problems of natural science. This problem has attracted human attention since time immemorial. However, in different eras and at different stages of development of human culture, this problem was solved in different ways. Theories concerning the origin of the Earth, and indeed the entire universe, are varied and far from reliable. Here are the main ones:
1. Creationism. According to this idea, life was created by a creator (from the Latin word create - to create).
2. Steady state hypothesis. Life, like the Universe itself, has not always existed and will exist forever, since it has no beginning and end.
3. The spontaneous generation hypothesis, according to which life arises spontaneously from inanimate matter.
4. The theory of panspermia is the idea that life was brought to Earth from the outside, from outer space. It must be said that this theory is still popular among scientists.
All these theories are mostly speculative and have no direct evidence. Currently, there is no consensus on the origin of life among scientists. The most widely recognized hypothesis in modern science is the one formulated by the Soviet scientist Acad. A.I. Oparin and the English scientist J. Haldane.
Theory of biochemical evolution
(biochemical theory of the origin of life)
In 1923, the Soviet scientist Oparin expressed the opinion that the Earth's atmosphere was not the same as it is now. Based on theoretical considerations, he suggested that life arose gradually from inorganic substances through long molecular evolution.
1. It is believed that the Earth and other planets of the solar system were formed from a gas and dust cloud about 4.5 billion years ago. In the first stages of its existence, the Earth had a very high temperature. As the planet cooled, heavy elements moved toward the center, while lighter elements remained on the surface. For example, iron atoms were concentrated in the center (according to scientists, currently the core of the earth consists of molten iron, heated to several thousand degrees C, and is 2 times smaller in size than the Moon). Less heavy atoms of silicon and aluminum form the earth's crust. The lightest remained in the outer layers of the cloud and formed the primary atmosphere of the Earth. It consisted of free H2 and its compounds: water, methane, ammonia and HCN and therefore was of a reducing nature (hydrogen compounds easily enter into chemical reactions, giving up hydrogen and at the same time oxidizing themselves).
Atmospheric components were exposed to various energy sources:
· Hard, close to X-ray short-wave radiation from the Sun
· Lightning discharges
High temperature in areas of lightning and volcanic activity (i.e. hot lava, hot springs, geysers)
· Shock waves from meteorites entering the earth's atmosphere.
As a result of these impacts, the chemically simple components of the atmosphere interacted, changing and becoming more complex. Molecules of sugars, amino acids, nitrogenous bases, organic acids (acetic, formic, lactic) and other simple organic compounds appeared.
The absence of oxygen in the atmosphere and a reducing environment were a necessary condition for the emergence of organic molecules by non-biological means. Oxygen interacts with organic substances and destroys them or deprives them of those properties that would be useful for prebiological systems. Therefore, if organic molecules on the primitive Earth came into contact with oxygen, they would not exist for long and would not have time to form more complex structures.
In 1953, Stanley Miller, in a series of experiments, simulated conditions that supposedly existed on the primitive Earth. Atmospheric conditions were created in a sealed flask (water vapor, ammonia, methane, hydrocyanic acid, carbon dioxide). The colorless contents of the flask were exposed to high temperatures and electrical discharges and as a result acquired a red tint due to the formation of fatty acids, urea, sugars and amino acids.
Other scientists have conducted similar experiments using different energy sources. In all experiments, in the absence of oxygen, it was possible to obtain a wide range of different organic products. Researchers were particularly interested in the possibility of the formation of amino acids - after all, they are the building blocks of protein molecules. Later it turned out that many simple compounds that are part of biological polymers - proteins, nucleic acids and polysaccharides - can be synthesized abiogenically.
The possibility of abiogenic synthesis of organic compounds is proven by the fact that they are also found in outer space. Hydrogen cyanide, formaldehyde, formic acid, methyl and ethyl alcohols and other simple organic compounds have been found in space. Some meteorites contain fatty acids, sugars, and amino acids. These compounds are formed today when gaseous products of volcanic eruptions and lava react with water.
All this indicates that organic compounds could have arisen purely chemically under the conditions that existed on Earth about 4 billion years ago. The necessary conditions for this are:
· Reductive nature of the atmosphere (lack of O 2)
· Heat
Energy sources (UV radiation from the Sun, lightning, etc.)
2. The next step was the formation of polymers from monomers.
As the Earth cooled, the water vapor contained in the atmosphere condensed, and rain fell on the Earth's surface, forming large expanses of water. The polymerization reaction of the primary units does not occur in an aqueous solution, since when two amino acids or two nucleotides are combined with each other, a water molecule is split off. The reaction in water will go in the opposite direction. The rate of breakdown (hydrolysis) of biopolymers will be greater than the rate of their synthesis. It is clear that biopolymers could not have arisen on their own in the primordial ocean.
Perhaps the primary synthesis of biopolymers occurred when the primary ocean was frozen or when its dry residue was heated.
American researcher Sydney Fox, heating a dry mixture of amino acids to 130C, showed that in this case the polymerization reaction occurs (the released water evaporates) and artificial proteinoids are obtained, similar to proteins with up to 200 or more amino acids in the chain. Dissolved in water, they had the properties of proteins, provided a nutrient medium for bacteria, and even catalyzed (accelerated) some chemical reactions, like real enzymes.
Perhaps they arose in the pre-biological era on the hot slopes of volcanoes, and then rains washed them into the primordial ocean. There is also a point of view that the synthesis of biopolymers took place directly in the primary atmosphere and the resulting compounds fell into the primary ocean in the form of dust particles.
This is how the prototypes of modern proteins and nucleic acids arose. Among the randomly formed polypeptides there could be those that had catalytic activity and could accelerate the processes of polynucleotide synthesis.
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Presentation - Biochemical evolution
Text of this presentation
Theory of abiogenesis (biochemical evolution). Model A. Oparin -J. Haldane. Experiments by S. Miller. Problems and contradictions of the theory
In 1923, the Soviet biochemist Alexei Oparin developed the theory of biochemical evolution.
A. I. Oparin, Russian biochemist, academician, published his first book on this problem of the origin of life through biochemical evolution back in 1924
March 2, 1894 – April 21, 1980
Billions of years ago, during the formation of the planet, the first organic substances were hydrocarbons, which were formed in the ocean from simpler compounds.
The basis of this theory was the idea:
A. Oparin considered the emergence of life as a single natural process, which consisted of the initial chemical evolution that took place under the conditions of the early Earth, which gradually moved to a qualitatively new level - biochemical evolution.
The essence of the hypothesis:
The origin of life on Earth is a long evolutionary process of the formation of living matter in the depths of nonliving matter.
This happened through chemical evolution, as a result of which the simplest organic substances were formed from inorganic ones under the influence of strong physicochemical factors.
Oparin identifies three stages of transition from inanimate to living matter:
1) the stage of synthesis of initial organic compounds from inorganic substances under the conditions of the primary atmosphere of the early Earth; 2) the stage of formation of biopolymers, lipids, hydrocarbons from accumulated organic compounds in the primary reservoirs of the Earth; 3) the stage of self-organization of complex organic compounds, the emergence on their basis and evolutionary improvement of the processes of metabolism and reproduction of organic structures, culminating in the formation of the simplest cell.
First stage (about 4 billion years ago)
As the planet cooled, water vapor in the atmosphere condensed and rained down on the Earth, forming huge expanses of water.
As the Earth's surface remained hot, the water evaporated and then, cooling in the upper atmosphere, fell back onto the planet's surface.
Thus, various salts and organic compounds were dissolved in the waters of the primary ocean
These processes continued for many millions of years
Second phase
Conditions on Earth are softening; under the influence of electrical discharges, thermal energy and ultraviolet rays on the chemical mixtures of the primary ocean, it has become possible to form complex organic compounds - biopolymers and nucleotides, which gradually combine and become more complex.
The result of the evolution of complex organic substances was the appearance of coacervates, or coacervate drops.
Coacervates are complexes of colloidal particles, the solution of which is divided into two layers:
layer rich in colloidal particles
liquid almost free of them
Coacervates turned out to be able to absorb various organic substances from the external environment, which provided the possibility of primary metabolism with the environment.
preserved coacervate drops had the ability to undergo primary metabolism
Third stage
Natural selection began to act
as a result, only a small part of the coacervates was preserved
Having reached a certain size, the mother drop could break up into daughter drops, which retained the features of the mother structure
Later, the theory of biochemical evolution was developed in the works of the English scientist John Haldane
J. Haldane, an English geneticist and biochemist, since 1929 developed ideas consonant with the ideas of A.I. Oparin.
Life was the result of long evolutionary carbon compounds. Substances similar in their chemical composition to proteins and other organic compounds that form the basis of living organisms arose on the basis of hydrocarbons.
John Haldane formulated a hypothesis
Subsequently, absorbing protein substances from the environment, the structure of the coacervates became more complex, and they became similar to primitive, but already living cells, and the chemical compounds of their internal composition allowed them to grow, mutate, metabolize and multiply.
Coacervate (from the Latin coacervātus - “gathered in a heap”) or “Primary broth” is a multimolecular complex, drops or layers with a higher concentration of diluted substance than in the rest of the solution of the same chemical composition.
The theory of biochemical evolution and the origin of life on Earth, expressed by Alexei Oparin, is recognized by many scientists, however, due to the large number of assumptions and assumptions, it raises some doubts.
Postulates that life arose on Earth precisely from inanimate matter, under conditions that existed on the planet billions of years ago. These conditions included the presence of energy sources, a certain temperature regime, water and other inorganic substances - precursors of organic compounds. The atmosphere then was oxygen-free (the source of oxygen today is plants, but then there were none).
"Oparin-Haldane hypothesis"
Stages of the development of life on Earth according to the Oparin-Haldane hypothesis
Time period Stages of the origin of life Events occurring on Earth
From 6.5 to 3.5 billion years ago 1 Formation of the primary atmosphere containing methane, ammonia, carbon dioxide, hydrogen, carbon monoxide and water vapor
2 Cooling of the planet (below the temperature of +100 °C on its surface); condensation of water vapor; formation of the primary ocean; dissolution of gases and minerals in its water; powerful thunderstorms Synthesis of simple organic compounds - amino acids, sugars, nitrogenous bases - as a result of the action of powerful electrical discharges (lightning) and ultraviolet radiation
3 Formation of the simplest proteins, nucleic acids, polysaccharides, fats; coacervates
From 3.5 to 3 billion years ago 4 Formation of protobionts capable of self-reproduction and regulated metabolism as a result of the emergence of membranes with selective permeability and interactions of nucleic acids and proteins
3 billion years ago 5 The emergence of organisms with a cellular structure (primary prokaryotes-bacteria)
Very convincing evidence of the possibility of implementing the 2nd and 3rd stages of life development was obtained as a result of numerous experiments on the artificial synthesis of biological monomers.
For the first time in 1953, S. Miller (USA) created a fairly simple installation in which he managed to synthesize a number of amino acids and other organic compounds from a mixture of gases and water vapor under the influence of ultraviolet irradiation and electrical discharges
A publication in the journal Science describes data that eluded scientists more than 50 years ago.
A young employee at the University of Chicago, Stanley Miller, conducts his famous experiments on the synthesis of biological molecules. 1953 //Archives of the Department of Chemistry of the University of California at San Diego
Then Nobel laureate Harold Urey, who received a prestigious prize for the discovery of heavy water and subsequently became interested in the problems of cosmochemistry,
inspired one of his students, Stanley Miller, with the theory of a prehistoric abiotic soup, from which, under the influence of external factors, the first organic molecules emerged.
April 29, 189 – January 5, 1981 (age 87)
In order to recreate reactions in the laboratory under conditions similar to those that prevailed on Earth billions of years ago, Miller developed an original chemical device.
The device consists of a large reaction flask containing vapors of methane, ammonia and hydrogen, into which hot water vapor is pumped from below. On top are tungsten electrodes that generate a spark discharge. By simulating the conditions of a thunderstorm in the vicinity of an active coastal volcano in this way, Miller hoped to obtain biological molecules through synthesis.
Boiling water (1) creates a stream of steam, which is amplified by the aspirator nozzle (inset), a spark jumping between two electrodes (2) starts a set of chemical transformations, the refrigerator (3) cools the stream of water vapor containing reaction products that settle in a trap ( 4).// Ned Shaw, Indiana University.
In his experiment, Miller used a gas mixture consisting of:
ammonia
methane
hydrogen
water vapor
According to Miller's assumption, it was this mixture that predominated in the Earth's primary atmosphere.
Since these gases could not react under natural conditions, Miller exposed them to electrical energy, simulating lightning discharges from which energy was supposed to be obtained in the early atmosphere
At a temperature of 100 ° C, the mixture was boiled for a week, systematically exposed to electrical discharges.
An analysis of chemosynthesis carried out at the end of the week showed that out of the twenty amino acids that form the basis of any protein, only three were formed
After the death of Stephen Miller, while sorting through his diaries and archives, relatives and colleagues discovered notes related to the works of the 50s, as well as several bottles with signatures.
The signatures indicated that the contents of the flasks were nothing more than synthesis products in Miller’s apparatus, preserved by the author in an inviolable form.
The experiments of Stanley Miller, who tried to replicate the origin of life on Earth in a test tube, were much more successful than Miller himself believed. Modern methods have made it possible to find not five, but all 22 amino acids in chemical vessels sealed by scientists many decades ago.
Over the next 20 years it was established:
The atmosphere in Miller's experience was fictitious
The Earth's early atmosphere was not made of methane and ammonia, but of nitrogen, carbon dioxide and water vapor, and Miller's experiment was nothing more than an outright lie.
In the experiments, to obtain amino acids, they took ready-made ammonia, and by itself, in an abiogenic way, it is formed only at high pressure and temperatures from an equimal mixture of hydrogen and nitrogen, in the presence of a catalyst
Miller used the “cold trap” mechanism in the experiment, that is, the resulting amino acids were immediately isolated from the external environment.
Without this mechanism, atmospheric conditions would immediately destroy these molecules.
Miller, using the “cold trap” method, himself crushed his own assertion about the possibility of the free formation of amino acids in the atmosphere.
As a result, all efforts showed that even under ideal laboratory conditions it is impossible to synthesize amino acids without a “cold trap” mechanism to prevent the breakdown of amino acids already under the influence of their own environment, so there can be no question of their accidental occurrence in nature.
Scientific problems of Miller's experiments
The resulting amino acids turned out to be “non-living”: they were in the wrong direction of rotation – the “chirality” effect. As a result of the experiment, many D-amino acids were obtained. D-amino acids are absent in the structure of a living organism.
“problems of chirality” As a result of the experiment, amino acids were obtained with different rotations (orientations) from the imaginary axis, which makes it almost impossible to combine them into proteins (b-ok)
chirality
The term "chirality" comes from the Greek word "chiros" - hand.