Research of the genetic code. The concept of a gene, genetic code

Thanks to the process of transcription in the cell, information is transferred from DNA to protein: DNA - mRNA - protein. The genetic information contained in DNA and mRNA is contained in the sequence of nucleotides in the molecules. How is information transferred from the “language” of nucleotides to the “language” of amino acids? This translation is carried out using the genetic code. A code, or cipher, is a system of symbols for translating one form of information into another. The genetic code is a system for recording information about the sequence of amino acids in proteins using the sequence of nucleotides in messenger RNA. How important exactly the sequence of arrangement of the same elements (four nucleotides in RNA) is for understanding and preserving the meaning of information can be seen in a simple example: by rearranging the letters in the word code, we get a word with a different meaning - doc. What properties does the genetic code have?

1. The code is triplet. RNA consists of 4 nucleotides: A, G, C, U. If we tried to designate one amino acid with one nucleotide, then 16 out of 20 amino acids would remain unencrypted. A two-letter code would encrypt 16 amino acids (from four nucleotides, 16 different combinations can be made, each of which contains two nucleotides). Nature has created a three-letter, or triplet, code. This means that each of the 20 amino acids is encoded by a sequence of three nucleotides, called a triplet or codon. From 4 nucleotides you can create 64 different combinations of 3 nucleotides each (4*4*4=64). This is more than enough to encode 20 amino acids and, it would seem, 44 codons are superfluous. However, it is not.

2. The code is degenerate. This means that each amino acid is encrypted by more than one codon (from two to six). The exceptions are the amino acids methionine and tryptophan, each of which is encoded by only one triplet. (This can be seen in the genetic code table.) The fact that methionine is encoded by a single OUT triplet has a special meaning that will become clear to you later (16).

3. The code is unambiguous. Each codon codes for only one amino acid. In all healthy people, in the gene carrying information about the beta chain of hemoglobin, the triplet GAA or GAG, I in sixth place, encodes glutamic acid. In patients with sickle cell anemia, the second nucleotide in this triplet is replaced by U. As can be seen from the table, the triplets GUA or GUG, which are formed in this case, encode the amino acid valine. You already know what such a replacement leads to from the section on DNA.

4. There are “punctuation marks” between genes. In printed text there is a period at the end of each phrase. Several related phrases make up a paragraph. In the language of genetic information, such a paragraph is an operon and its complementary mRNA. Each gene in the operon encodes one polypeptide chain - a phrase. Since in some cases several different polypeptide chains are sequentially created from the mRNA matrix, they must be separated from each other. For this purpose, there are three special triplets in the genetic code - UAA, UAG, UGA, each of which indicates the termination of the synthesis of one polypeptide chain. Thus, these triplets function as punctuation marks. They are found at the end of every gene. There are no "punctuation marks" inside the gene. Since the genetic code is similar to a language, let us analyze this property using the example of a phrase composed of triplets: once upon a time there was a quiet cat, that cat was dear to me. The meaning of what is written is clear, despite the absence of punctuation marks. If we remove one letter in the first word (one nucleotide in the gene), but also read in triplets of letters, then the result will be nonsense: ilb ylk ott ilb yls erm ilm no otk Violation of the meaning also occurs when one or two nucleotides are lost from a gene.The protein that will be read from such a damaged gene will have nothing in common with the protein that was encoded by the normal gene.

6. The code is universal. The genetic code is the same for all creatures living on Earth. In bacteria and fungi, wheat and cotton, fish and worms, frogs and humans, the same triplets encode the same amino acids.

Chemical composition and structural organization of the DNA molecule.

Nucleic acid molecules are very long chains consisting of many hundreds and even millions of nucleotides. Any nucleic acid contains only four types of nucleotides. The functions of nucleic acid molecules depend on their structure, the nucleotides they contain, their number in the chain and the sequence of the compound in the molecule.

Each nucleotide consists of three components: a nitrogenous base, a carbohydrate and a phosphoric acid. IN compound each nucleotide DNA includes one of four types of nitrogenous bases (adenine - A, thymine - T, guanine - G or cytosine - C), as well as deoxyribose carbon and a phosphoric acid residue.

Thus, DNA nucleotides differ only in the type of nitrogenous base.
The DNA molecule consists of a huge number of nucleotides connected in a chain in a certain sequence. Each type of DNA molecule has its own number and sequence of nucleotides.

DNA molecules are very long. For example, to write down the sequence of nucleotides in DNA molecules from one human cell (46 chromosomes) in letters would require a book of about 820,000 pages. The alternation of four types of nucleotides can form an infinite number of variants of DNA molecules. These structural features of DNA molecules allow them to store a huge amount of information about all the characteristics of organisms.

In 1953, the American biologist J. Watson and the English physicist F. Crick created a model of the structure of the DNA molecule. Scientists have found that each DNA molecule consists of two chains interconnected and spirally twisted. It looks like a double helix. In each chain, four types of nucleotides alternate in a specific sequence.

Nucleotide DNA composition varies among different types of bacteria, fungi, plants, and animals. But it does not change with age and depends little on environmental changes. Nucleotides are paired, that is, the number of adenine nucleotides in any DNA molecule is equal to the number of thymidine nucleotides (A-T), and the number of cytosine nucleotides is equal to the number of guanine nucleotides (C-G). This is due to the fact that the connection of two chains to each other in a DNA molecule is subject to a certain rule, namely: adenine of one chain is always connected by two hydrogen bonds only with Thymine of the other chain, and guanine - by three hydrogen bonds with cytosine, that is, the nucleotide chains of one molecule DNA is complementary, complementing each other.

Nucleic acid molecules - DNA and RNA - are made up of nucleotides. DNA nucleotides include a nitrogenous base (A, T, G, C), the carbohydrate deoxyribose and a phosphoric acid molecule residue. The DNA molecule is a double helix, consisting of two chains connected by hydrogen bonds according to the principle of complementarity. The function of DNA is to store hereditary information.

Properties and functions of DNA.

DNA is a carrier of genetic information recorded in the form of a sequence of nucleotides using a genetic code. DNA molecules are associated with two fundamental properties of living things organisms - heredity and variability. During a process called DNA replication, two copies of the original strand are formed, which are inherited by daughter cells when they divide, so that the resulting cells are genetically identical to the original.

Genetic information is realized during gene expression in the processes of transcription (synthesis of RNA molecules on a DNA template) and translation (synthesis of proteins on an RNA template).

The sequence of nucleotides “encodes” information about different types of RNA: messenger or template (mRNA), ribosomal (rRNA) and transport (tRNA). All these types of RNA are synthesized from DNA during the process of transcription. Their role in protein biosynthesis (translation process) is different. Messenger RNA contains information about the sequence of amino acids in a protein, ribosomal RNA serves as the basis for ribosomes (complex nucleoprotein complexes, the main function of which is the assembly of proteins from individual amino acids based on mRNA), transfer RNAs deliver amino acids to the site of protein assembly - to the active center of the ribosome, " crawling" on mRNA.

Genetic code, its properties.

Genetic code- a method characteristic of all living organisms of encoding the amino acid sequence of proteins using a sequence of nucleotides. PROPERTIES:

1. Triplety- a meaningful unit of code is a combination of three nucleotides (triplet, or codon).
2. Continuity- there are no punctuation marks between triplets, that is, the information is read continuously.
3. Non-overlapping- the same nucleotide cannot simultaneously be part of two or more triplets (not observed for some overlapping genes of viruses, mitochondria and bacteria, which encode several frameshift proteins).
4. Uniqueness (specificity)- a specific codon corresponds to only one amino acid (however, the UGA codon has Euplotes crassus encodes two amino acids - cysteine ​​and selenocysteine)
5. Degeneracy (redundancy)- several codons can correspond to the same amino acid.
6. Versatility- the genetic code works the same in organisms of different levels of complexity - from viruses to humans (genetic engineering methods are based on this; there are a number of exceptions, shown in the table in the section “Variations of the standard genetic code” below).
7. Noise immunity- mutations of nucleotide substitutions that do not lead to a change in the class of the encoded amino acid are called conservative; nucleotide substitution mutations that lead to a change in the class of the encoded amino acid are called radical.

5. Autoreproduction of DNA. Replicon and its functioning .

The process of self-reproduction of nucleic acid molecules, accompanied by the inheritance (from cell to cell) of exact copies of genetic information; R. carried out with the participation of a set of specific enzymes (helicase<helicase>controlling the unwinding of the molecule DNA, DNA-polymerase<DNA polymerase> I and III, DNA-ligase<DNA ligase>), proceeds in a semi-conservative manner with the formation of a replication fork<replication fork>; on one of the circuits<leading strand> the synthesis of the complementary chain is continuous, and on the other<lagging strand> occurs due to the formation of Dkazaki fragments<Okazaki fragments>; R. - a high-precision process, the error rate of which does not exceed 10 -9; in eukaryotes R. can occur at several points of one molecule at once DNA; speed R. eukaryotes have about 100, and bacteria have about 1000 nucleotides per second.

6. Levels of eukaryotic genome organization .

In eukaryotic organisms, the mechanism of transcription regulation is much more complex. As a result of cloning and sequencing of eukaryotic genes, specific sequences involved in transcription and translation were discovered.
A eukaryotic cell is characterized by:
1. The presence of introns and exons in the DNA molecule.
2. Maturation of mRNA - excision of introns and stitching of exons.
3. The presence of regulatory elements that regulate transcription, such as: a) promoters - 3 types, each of which is occupied by a specific polymerase. Pol I replicates ribosomal genes, Pol II replicates protein structural genes, Pol III replicates genes encoding small RNAs. The Pol I and Pol II promoter are located in front of the transcription initiation site, the Pol III promoter is within the structural gene; b) modulators - DNA sequences that enhance the level of transcription; c) amplifiers - sequences that enhance the level of transcription and act regardless of their position relative to the coding part of the gene and the state of the starting point of RNA synthesis; d) terminators - specific sequences that stop both translation and transcription.
These sequences differ from prokaryotic sequences in their primary structure and location relative to the start codon, and bacterial RNA polymerase does not “recognize” them. Thus, for the expression of eukaryotic genes in prokaryotic cells, the genes must be under the control of prokaryotic regulatory elements. This circumstance must be taken into account when constructing expression vectors.

7. Chemical and structural composition of chromosomes .

Chemical chromosome composition - DNA - 40%, Histone proteins - 40%. Non-histone - 20% some RNA. Lipids, polysaccharides, metal ions.

The chemical composition of a chromosome is a complex of nucleic acids with proteins, carbohydrates, lipids and metals. The chromosome regulates gene activity and restores it in the event of chemical or radiation damage.

STRUCTURAL????

Chromosomes- nucleoprotein structural elements of the cell nucleus, containing DNA, which contains the hereditary Information of the organism, are capable of self-reproduction, have structural and functional individuality and retain it over a number of generations.

in the mitotic cycle the following features of the structural organization of chromosomes are observed:

There are mitotic and interphase forms of the structural organization of chromosomes, mutually transforming into each other in the mitotic cycle - these are functional and physiological transformations

8. Levels of packaging of hereditary material in eukaryotes .

Structural and functional levels of organization of hereditary material of eukaryotes

Heredity and variability provide:

1) individual (discrete) inheritance and change of individual characteristics;

2) reproduction in individuals of each generation of the entire complex of morphofunctional characteristics of organisms of a particular biological species;

3) redistribution in species with sexual reproduction in the process of reproduction of hereditary inclinations, as a result of which the descendant has a combination of characteristics that is different from their combination in the parents. The patterns of inheritance and variability of traits and their sets follow from the principles of the structural and functional organization of genetic material.

There are three levels of organization of the hereditary material of eukaryotic organisms: gene, chromosomal and genomic (genotype level).

The elementary structure of the gene level is the gene. The transfer of genes from parents to offspring is necessary for the development of certain characteristics. Although several forms of biological variability are known, only a violation of the structure of genes changes the meaning of hereditary information, in accordance with which specific characteristics and properties are formed. Thanks to the presence of the gene level, individual, separate (discrete) and independent inheritance and changes in individual characteristics are possible.

Genes in eukaryotic cells are distributed in groups along chromosomes. These are the structures of the cell nucleus, which are characterized by individuality and the ability to reproduce themselves with the preservation of individual structural features over generations. The presence of chromosomes determines the identification of the chromosomal level of organization of hereditary material. The placement of genes on chromosomes affects the relative inheritance of traits and makes it possible for the function of a gene to be influenced by its immediate genetic environment - neighboring genes. The chromosomal organization of hereditary material serves as a necessary condition for the redistribution of the hereditary inclinations of parents in offspring during sexual reproduction.

Despite the distribution on different chromosomes, the entire set of genes functionally behaves as a whole, forming a single system representing the genomic (genotypic) level of organization of the hereditary material. At this level, there is a wide interaction and mutual influence of hereditary inclinations, localized both in one and in different chromosomes. The result is the mutual correspondence of genetic information of different hereditary inclinations and, consequently, the development of traits balanced in time, place and intensity in the process of ontogenesis. The functional activity of genes, the mode of replication and mutational changes in the hereditary material also depend on the characteristics of the genotype of the organism or cell as a whole. This is evidenced, for example, by the relativity of the property of dominance.

Eu - and heterochromatin.

Some chromosomes appear condensed and intensely colored during cell division. Such differences were called heteropyknosis. The term " heterochromatin" There are euchromatin - the main part of mitotic chromosomes, which undergoes the usual cycle of compaction and decompaction during mitosis, and heterochromatin- regions of chromosomes that are constantly in a compact state.

In most species of eukaryotes, chromosomes contain both ew- and heterochromatic regions, the latter making up a significant part of the genome. Heterochromatin located in pericentromeric, sometimes in peritomeric regions. Heterochromatic regions were discovered in the euchromatic arms of chromosomes. They look like inclusions (intercalations) of heterochromatin into euchromatin. Such heterochromatin called intercalary. Chromatin compaction. Euchromatin and heterochromatin differ in compaction cycles. Euhr. goes through a full cycle of compaction-decompaction from interphase to interphase, hetero. maintains a state of relative compactness. Differential stainability. Different areas of heterochromatin are stained with different dyes, some areas with one, others with several. By using various dyes and using chromosomal rearrangements that break up heterochromatic regions, it has been possible to characterize many small regions in Drosophila where the affinity for the stains is different from neighboring regions.

10. Morphological features of the metaphase chromosome .

The metaphase chromosome consists of two longitudinal strands of deoxyribonucleoprotein - chromatids, connected to each other in the region of the primary constriction - the centromere. A centromere is a specially organized region of a chromosome that is common to both sister chromatids. The centromere divides the chromosome body into two arms. Depending on the location of the primary constriction, the following types of chromosomes are distinguished: equal-armed (metacentric), when the centromere is located in the middle and the arms are approximately equal in length; unequal arms (submetacentric), when the centromere is displaced from the middle of the chromosome, and the arms are of unequal length; rod-shaped (acrocentric), when the centromere is shifted to one end of the chromosome and one arm is very short. There are also point (telocentric) chromosomes; they lack one arm, but they are not present in the human karyotype (chromosome set). Some chromosomes may have secondary constrictions that separate a region called a satellite from the chromosome body.

Ecology of life. Psychology: At all times, people were interested in their future, so they often turned to fortune-tellers and soothsayers. Influential people in power were especially worried about what fate had in store for them, so they could keep personal prophets with them. In more ancient times, for example, among the Greeks, even the gods themselves depended on fate and obeyed the goddesses of fate.

At all times, people were interested in their future, so they often turned to fortune-tellers and soothsayers. Influential people in power were especially worried about what fate had in store for them, so they could keep personal prophets with them. In more ancient times, for example, among the Greeks, even the gods themselves depended on fate and obeyed the goddesses of fate. In modern times, science and scientists are already concerned with fate; there are many interesting discoveries that help us understand our essence and future.

Science has found that indeed, there is a certain scenario of fate based on a person’s genetic code, which determines what kind of temperament he will have and what abilities he will have.

The genetic code is formed by our parents and contains qualities and capabilities. But their presence does not always mean their embodiment - they can develop under favorable conditions or not develop at all.

Abilities are realized in maximum quantities in psychologically healthy people who constantly try to develop spiritually and physically. They are always learning and reaching new stages of development. People suffering from various neurotic disorders find many excuses and reasons why they cannot achieve success, blaming fate and life for this.

If temperament is a physiological characteristic and depends on the gene set, then character is formed in the process of education, with the help and direct participation of parents. While the child is still not independent, mom and dad and how they behave play a big role in his life. Education plays a very important role; it is like a sculptor - it creates a finished work from the foundation.

Two children raised in the same family will differ in character and behavior, because they have different genetic codes and temperaments, so in the end the siblings may not be alike at all. Character is a system of persistent, almost permanent individual properties of a person that reflect her attitude and behavior towards herself, people and work. Character has several basic qualities - integrity, activity, hardness, stability and plasticity.

Quantitative parameters

Integrity– this is the absence of contradictions in relation to people, oneself, the world around us and work. Integrity is expressed in balance, in the totality of all personality traits and interests, in the compatibility of attitudes towards different aspects of life. I believe that most characters are holistic, in the sense that a person's outer behavior reflects his inner system of relationships.

This means that if a person behaves duplicitously, then inside he has sharp contradictions in his content. This is how women often choose their partners unsuccessfully, being psychologically unprepared and not knowing what compliments and declarations of love from their chosen ones mean.

You must listen carefully and weigh every word. If a man tells a girl that there is no one more beautiful than her, that she is kinder and better than everyone else, it means that he is a womanizer. He has someone to compare with, and he can soon become carried away by another, and each next one will also be the most beautiful.

If a young man insists that he does not see the meaning of life without his beloved, that without her he will be lost and completely lost, then most likely he is an alcoholic or someone who will definitely become one in the future. It is extremely important to know these behavioral points; the broader your horizons, the less likely it is that unhappy personal stories will appear in your life.

Activity is expressed in the ability to counteract unfavorable circumstances and the amount of energy that goes into fighting obstacles. Depending on the activity, characters are strong and weak. Strength of character directly depends on the sociogene - the personal complex. A person with a weak character can also fulfill the requirements dictated by the sociogene, because the implementation of activity is determined by character. And if the direction of activity is combined with fate, then the person will have enough energy.

Hardness manifests itself in the persistence and perseverance of a person in the process of achieving a goal and defending his opinion. Sometimes excessive strength of character can become stubbornness. Resilience determines the immutability of our character, despite the variability of the world, events and our position in society. Character is a fairly stable characteristic, so it is extremely difficult to change it. Individuals with an unstable character are likely to have many psychological problems in general, and one of the main ones is instability.

Plastic– the ability to adapt to a changed world, the ability to change and adapt to a completely unusual reality, in stressful situations. If even with fundamental changes the character remains unchanged, this indicates its rigidity.

Quantitative parameters

The famous psychotherapist Berne, taking into account the huge variety of character qualities, identified three main parameters by which character can be determined: relationships with oneself are “I”, relationships with loved ones are “You”, relationships with all people in general are “They” .

Berne suggested that these qualities, instilled in a person by parents in childhood, can have both a positive and negative connotation, and determine his future behavior and life path, which he called the “scenario”. Often people do not understand why such events happen to them and do not connect them with their childhood. I added a fourth parameter to Bern’s system – “Labor”.

If a person’s childhood went well and he received a good upbringing, then all the parameters will be positive, with a plus sign. But if the parents made mistakes in their upbringing, then, accordingly, some or all of the parameters acquire a minus sign, and a complex - a sociogene - can be formed, which will greatly influence the behavior and fate of a person.

The individual is harmonious and healthy personality with the parameter “I” with “+”. This means he has the right upbringing, he adequately evaluates himself and recognizes himself as successful. Position should not be confused with self-esteem. The position is practically not realized by the person and is formed under the influence of parents in childhood; its direction is quite difficult to change.

Self-esteem may depend on the situation. If a person has too high demands on himself and on events, then self-esteem is low. No amount of success or luck will satisfy a person; he will always want to do better, always see shortcomings and disadvantages.

At positions "You" with "+" relationships with loved ones and surrounding people are prosperous, friendly, and bring joy. A person is always ready to help and support his loved ones; he considers them successful people. If “-” predominates in the “You” parameter, this means that the person’s mood is initially hostile and conflictual with respect to close people. Often such individuals are distinguished by caustic humor, criticism of everything and everyone, pickiness and dissatisfaction. To build relationships with such people, you have to constantly give in to them.

When communicating, they often choose the role of the Persecutor, but there are also Deliverers. This role hides aggression that is not visible at first glance. For example, these are managers who take on all the important issues and complex tasks, thereby hindering the growth of their colleagues.

When the parameter “They” has the value “+”- a person loves to communicate with people, meet people and make new friends. He sees a lot of positive, interesting and worthy things in people. If the parameter “They” is “-”, then the person first notices shortcomings in people, and only then their advantages. At the same time, he himself is extremely shy, difficult to communicate and is reluctant to make contact and make new acquaintances.

When “Labor” for an individual in “+”, then he enjoys the process of work, prefers to solve complex problems for self-development and professional growth, and he enjoys finding creative solutions to issues. The material component is not so important for him, but he achieves high performance and success.

If “Labor” has a “-” sign, then the person has a clear focus on material gain. Money, and not development, worries him primarily in any work. Therefore, he is constantly chasing larger sums and a better life, in the pursuit forgetting to live here and now.

If “-” is present in one of the parameters, then the positive value of the others is doubly enhanced, for example, if “You” is with “-”, then the positive value of “I” may be too hypertrophied.

Now it is clear to us that a person can be harmonious, healthy and prosperous only with all the positive meanings. Only such a person will correctly and adequately perceive himself, his victories and defeats, his loved ones and their shortcomings and advantages. He will successfully contact people, expand his circle of acquaintances, succeed in work and his favorite activities, and experience life's upheavals with wisdom and calm.

This might interest you:

There are such people and there are many of them. And so that there are more and more such individuals, young parents should raise their children more carefully, without interfering with their development and exploration of the world. Support, but do not interfere, do not dictate your own rules and do not break the psyche of children.

After all, no one bothers the tree to grow and it grows strong and healthy, and so do children - you just need a little help, but not try to impose your life plan. The child himself knows what he wants and what is interesting to him, and it is best not to interfere with his choice, because this is his destiny. published

In any cell and organism, all anatomical, morphological and functional features are determined by the structure of the proteins that comprise them. The hereditary property of the body is the ability to synthesize certain proteins. Amino acids are located in a polypeptide chain, on which biological characteristics depend.
Each cell has its own sequence of nucleotides in the polynucleotide chain of DNA. This is the genetic code of DNA. Through it, information about the synthesis of certain proteins is recorded. This article describes what the genetic code is, its properties and genetic information.

A little history

The idea that there might be a genetic code was formulated by J. Gamow and A. Down in the mid-twentieth century. They described that the nucleotide sequence responsible for the synthesis of a particular amino acid contains at least three units. Later they proved the exact number of three nucleotides (this is a unit of genetic code), which was called a triplet or codon. There are sixty-four nucleotides in total, because the acid molecule where RNA occurs is made up of four different nucleotide residues.

What is genetic code

The method of encoding the sequence of amino acid proteins due to the sequence of nucleotides is characteristic of all living cells and organisms. This is what the genetic code is.
There are four nucleotides in DNA:

• adenine - A;
• guanine - G;
• cytosine - C;
• thymine - T.

They are denoted by capital Latin or (in Russian-language literature) Russian letters.
RNA also contains four nucleotides, but one of them is different from DNA:

• adenine - A;
• guanine - G;
• cytosine - C;
• uracil - U.

All nucleotides are arranged in chains, with DNA having a double helix and RNA having a single helix.
Proteins are built on twenty amino acids, where they, located in a certain sequence, determine its biological properties.

Properties of the genetic code

Tripletity. A unit of genetic code consists of three letters, it is triplet. This means that the twenty amino acids that exist are encoded by three specific nucleotides called codons or trilpets. There are sixty-four combinations that can be created from four nucleotides. This amount is more than enough to encode twenty amino acids.
Degeneracy. Each amino acid corresponds to more than one codon, with the exception of methionine and tryptophan.
Unambiguity. One codon codes for one amino acid. For example, in a healthy person's gene with information about the beta target of hemoglobin, a triplet of GAG and GAA encodes A in everyone who has sickle cell disease, one nucleotide is changed.
Collinearity. The sequence of amino acids always corresponds to the sequence of nucleotides that the gene contains.
The genetic code is continuous and compact, which means that it has no punctuation marks. That is, starting at a certain codon, continuous reading occurs. For example, AUGGGUGTSUUAAUGUG will be read as: AUG, GUG, TSUU, AAU, GUG. But not AUG, UGG and so on or anything else.
Versatility. It is the same for absolutely all terrestrial organisms, from humans to fish, fungi and bacteria.

Table

Not all available amino acids are included in the table presented. Hydroxyproline, hydroxylysine, phosphoserine, iodine derivatives of tyrosine, cystine and some others are absent, since they are derivatives of other amino acids encoded by m-RNA and formed after modification of proteins as a result of translation.
From the properties of the genetic code it is known that one codon is capable of encoding one amino acid. The exception is the genetic code, which performs additional functions and encodes valine and methionine. The mRNA, being at the beginning of the codon, attaches t-RNA, which carries formylmethione. Upon completion of the synthesis, it is cleaved off and takes the formyl residue with it, transforming into a methionine residue. Thus, the above codons are the initiators of the synthesis of the polypeptide chain. If they are not at the beginning, then they are no different from the others.

Genetic information

This concept means a program of properties that is passed down from ancestors. It is embedded in heredity as a genetic code.
The genetic code is realized during protein synthesis:

• messenger RNA;
• ribosomal rRNA.

Information is transmitted through direct communication (DNA-RNA-protein) and reverse communication (medium-protein-DNA).
Organisms can receive, store, transmit it and use it most effectively.
Passed on by inheritance, information determines the development of a particular organism. But due to interaction with the environment, the reaction of the latter is distorted, due to which evolution and development occur. In this way, new information is introduced into the body.

Decoding the human code

In the nineties, the Human Genome Project was launched, as a result of which genome fragments containing 99.99% of human genes were discovered in the 2000s. Fragments that are not involved in protein synthesis and are not encoded remain unknown. Their role remains unknown for now.

Last discovered in 2006, chromosome 1 is the longest in the genome. More than three hundred and fifty diseases, including cancer, appear as a result of disorders and mutations in it.

The role of such studies can hardly be overestimated. When they discovered what the genetic code is, it became known according to what patterns development occurs, how the morphological structure, psyche, predisposition to certain diseases, metabolism and defects of individuals are formed.

Today it is no secret to anyone that the life program of all living organisms is written on a DNA molecule. The easiest way to imagine a DNA molecule is as a long ladder. The vertical posts of this staircase are made up of molecules of sugar, oxygen and phosphorus. All the important operating information in the molecule is written on the rungs of the ladder - they consist of two molecules, each of which is attached to one of the vertical posts. These molecules—the nitrogenous bases—are called adenine, guanine, thymine, and cytosine, but they are usually simply designated by the letters A, G, T, and C. The shape of these molecules allows them to form bonds—complete ladders—only of a certain type. These are connections between the bases A and T and between the bases G and C (the pair thus formed is called "base pair"). There cannot be any other types of connections in a DNA molecule.

By going down the steps along one strand of a DNA molecule, you get a sequence of bases. It is this message in the form of a sequence of bases that determines the flow of chemical reactions in the cell and, consequently, the characteristics of the organism possessing this DNA. According to the central dogma of molecular biology, the DNA molecule encodes information about proteins, which, in turn, act as enzymes ( cm. Catalysts and enzymes) regulate all chemical reactions in living organisms.

The strict correspondence between the sequence of base pairs in a DNA molecule and the sequence of amino acids that make up protein enzymes is called the genetic code. The genetic code was deciphered soon after the discovery of the double-stranded structure of DNA. It was known that the newly discovered molecule informational, or matrix RNA (mRNA, or mRNA) carries information written on DNA. Biochemists Marshall W. Nirenberg and J. Heinrich Matthaei of the National Institutes of Health in Bethesda, near Washington, D.C., conducted the first experiments that led to clues to the genetic code.

They began by synthesizing artificial mRNA molecules consisting only of the repeating nitrogenous base uracil (which is an analogue of thymine, "T", and forms bonds only with adenine, "A", from the DNA molecule). They added these mRNAs to test tubes with a mixture of amino acids, and in each tube only one of the amino acids was labeled with a radioactive label. The researchers discovered that the mRNA they artificially synthesized initiated protein formation in only one test tube, which contained the labeled amino acid phenylalanine. So they established that the sequence “—U—U—U—” on the mRNA molecule (and, therefore, the equivalent sequence “—A—A—A—” on the DNA molecule) encodes a protein consisting only of the amino acid phenylalanine. This was the first step towards deciphering the genetic code.

Today it is known that three base pairs of a DNA molecule (this triplet is called codon) code for one amino acid in a protein. By performing experiments similar to those described above, geneticists eventually deciphered the entire genetic code, in which each of the 64 possible codons corresponds to a specific amino acid.