At the heart of almost everything genetic research lies the concept variations . This concept includes all types of DNA sequence changes ( mutations ), observed at the chromosomal or gene levels. On the one hand, genome variations explain interindividual diversity; on the other hand, mutations can lead to pathogenic changes in the functioning of the body, thus being the cause of a hereditary disease. You should also introduce several terms used to describe the process of mutational change in DNA: locus - a specific region of a chromosome containing specific DNA sequences or genes, allele - two or more alternative forms of a gene located at the same locus of a pair of homologous chromosomes. If a difference in the DNA sequence of two alleles of the same locus is observed with a frequency of more than 1% in the general population, then this type of variation is designated polymorphism . A change in DNA sequence that has a lower frequency is usually called mutation . There are two main types of mutations associated with hereditary pathology: chromosomal (change in the number and/or structure of chromosomes in a cell) and genetic (change in DNA sequence in a specific gene). Based on this classification, it is possible to identify areas of genetic research into DNA sequence violations leading to hereditary diseases, which are studied medical genetics , namely, the search for changes in the sequences of nucleic acids and proteins on molecular level (molecular genetics ) and the study of changes in the number, structure and organization of chromosomes ( medical cytogenetics ).
Molecular genetic research is based on modern ideas about the features of the DNA molecule and the biochemical processes of transcription and translation. Their main goal is to identify gene mutations leading to characteristic phenotypic manifestations. Gene mutations are changes in the location, loss and gain of DNA relative to its linear sequence found normally. The most common types of gene mutations are substitutions, losses and/or insertions of a single nucleotide. The latter are designated by the abbreviation SNP (single nucleotide polymorphsims) and are among the most common in the human genome. On average, SNPs leading to variation between alleles in one individual occur every 1500 base pairs. However, most of them are located in non-coding sequences and generally have no phenotypic consequences. If a change in the DNA sequence occurs in a gene encoding a protein, then it is highly likely to be associated with disorders of the body. There is the following classification of gene mutations:
Missense mutations- replacement of one nucleotide with another or nonsynonymous DNA sequence changes . Theoretically, two types of such mutations can be distinguished: conservative And non-conservative . Conservative missense mutations lead to the replacement of one codon with an equivalent one (codons encoding the same amino acid residue) or with a codon of another amino acid residue that does not change physicochemical characteristics protein encoded by the corresponding gene. Non-conservative missense mutations, as a rule, change the biochemical properties of the protein and, therefore, lead to disruption of its functional activity.
Nonsense mutation- changes in the coding sequence of DNA, leading to the formation of a stop codon, as a result of which a protein is synthesized in which some part of its sequence is missing.
Frameshift mutation- any changes in the DNA sequence of a gene (mainly losses or insertions of nucleotides) that lead to a shift in the reading of the sequence during transcription. The result of this is the synthesis of a completely new protein or the formation messenger RNA, which does not carry any information regarding the amino acid sequence.
Non-pathogenic DNA sequence changes- DNA sequence variations, including conservative missense mutations, or so-called synonymous mutations , which do not change the encoded information in the DNA of the gene or do not affect the functional activity of protein macromolecules.
Mutations also occur in non-coding DNA sequences (introns). This type of variation usually has no phenotypic consequences. However, with a shift in the reading frame or the formation of alternative forms of protein macromolecules ( alternative splicing ), these variations can lead to disruption of the functional activity of protein macromolecules and, as a consequence, phenotypic consequences. In this context, the identification of pathogenic mutations seems difficult, since the concept of “norm” in medical genetic research is quite relative, due to the fact that at the molecular level the human genome is largely unstable. In other words, only recurrent mutations (the most common recurrent mutations found in individuals with a known hereditary disease) may be considered pathogenic. In cases where a new mutation is discovered, there is a need for molecular genetic studies of the patient's close relatives to determine whether it is the cause of the disease.
Chromosomal mutations (abnormalities) are associated either with various structural rearrangements of chromosomes, or with a change in their number (n). Numerical changes in the set of chromosomes ( karyotype ) can be of two types: polyploidy - multiplication of the complete chromosome set (3n, 4n, etc.), or genome, a multiple of the haploid number of chromosomes (in the literature sometimes referred to as genomic mutations ); aneuploidy - an increase or decrease in the number of chromosomes in a set, not a multiple of the haploid one. These quantitative changes in the karyotype are usually caused by disorders of meiosis or mitosis. Numerical chromosomal abnormalities in the form of aneuploidy are divided into monosomy (loss of a chromosome or part of it - partial monosomy) and trisomy or polysomy (acquisition of one/several chromosomes or part thereof - partial trisomy). These karyotype changes are associated with a complex of congenital malformations and, as a rule, with diseases accompanied mental retardation, or severe mental disorders. Currently, cases of changes in the chromosome set involving sex chromosomes and some autosomes in schizophrenia and autism have been described. For example, up to 5-15% of children with autistic disorders have chromosomal abnormalities. This allows us to consider chromosomal imbalance in the body as one of possible reasons some cases of mental illness.
Structural changes can affect the entire chromosome, and can also be accompanied by a change in the amount of genetic material in the nucleus or its movement. Balanced chromosomal abnormalities are rearrangements due to which karyotypes arise with an unchanged set of genes, but their location within chromosomes or between chromosomes differs from normal. In most cases, carriers of balanced chromosomal abnormalities are phenotypically normal, but their offspring are at great risk of having an unbalanced karyotype, but in in some cases carriers of a balanced karyotype may have various congenital defects and/or microanomalies, as well as neuropsychological development disorders. If structural chromosomal mutations result in loss or gain of genetic material, then they are unbalanced chromosomal abnormalities .
Cytogenetically, structural rearrangements are classified according to the principle of linear sequence of gene arrangement: deletions (loss of chromosomal sections), duplications (doubling of chromosomal regions), inversions (inversion by 180° relative to the normal sequence of chromosomal regions), insertions (insertions of chromosomal regions) and translocations (change in the arrangement of chromosomal regions) of chromosomes.
Of great importance is the study of chromosomal mutations under the influence of factors external environment. It has been shown that human chromosomes are highly sensitive to the effects of radiation and chemicals, which are commonly called mutagenic factors ( mutagens ). When analyzing the impact of these factors, it is necessary to distinguish between disorders in somatic and germ cells. The former directly affect the vital activity of the organism under study, while the latter appear in subsequent generations. Chromosome mutations in germ cells lead to the formation of aberrant gametes, which can result in the death of zygotes, embryos in the early stages of intrauterine development, and the birth of children with specific or nonspecific chromosomal abnormalities, which manifest themselves in the form of a certain clinical picture or a certain phenotype. Mutations of chromosomes in somatic cells lead to the formation of nonspecific chromosomal abnormalities in the form of chromosomal or chromatid gaps, breaks, and exchanges in the karyotype, which do not lead to a specific phenotype characteristic of a particular disease. Such mutations are not inherited. It should be noted that when studying this type of impact of mutagenic factors, it is possible to evaluate qualitatively and quantitatively the effect ionizing radiation, chemicals, viruses, but the data obtained cannot be transferred to germ cells, the result of which is chromosomal diseases in children.
Chromosomal abnormalities can manifest themselves in so-called mosaic forms, which are caused by improper cell division at various stages of embryonic and postnatal development. This allows chromosomal abnormalities to be divided into mosaic And regular (an abnormal karyotype is observed in all cells of the body). Chromosomal mosaicism represents the presence of several populations of cells with various friends from each other to chromosome sets. As a rule, with mosaic forms of chromosomal abnormalities, there is an absence of individual clinical signs of a particular chromosomal syndrome and a milder course of the disease, but some symptoms are almost always present. Mosaic structural chromosomal anomalies are observed quite rarely, therefore, when we talk about mosaic chromosomal anomalies, we mainly mean numerical anomalies, the mosaic forms of which have a fairly high population frequency. It should also be noted the phenomenon tissue-specific chromosomal mosaicism - cells with an abnormal chromosome set are present only in a certain tissue of the body.
Mutations (from the Latin mutatio - to change) are inherited structural changes in genes.
Large mutations (genomic rearrangements) are accompanied by loss or changes in relatively large sections of the genome; such mutations are usually irreversible.
Small (point) mutations are associated with the loss or addition of individual DNA nucleotides. In this case, only a small number of characteristics change. Such altered bacteria can completely return to their original state (revert).
Bacteria with altered characteristics are called mutants. Factors that cause the formation of mutants are called mutagens.
Bacterial mutations are divided into spontaneous and induced. Spontaneous (spontaneous) mutations occur under the influence of uncontrolled factors, that is, without the intervention of an experimenter. Induced (directed) mutations appear as a result of the treatment of microorganisms with special mutagens (chemicals, radiation, temperature and
As a result of bacterial mutations, the following may be observed: a) changes in morphological properties b) changes in cultural properties c) the emergence of drug resistance in microorganisms d) loss of the ability to synthesize amino acids, utilize carbohydrates and other nutrients e) weakening of pathogenic properties, etc.
If a mutation leads to the fact that mutagenic cells acquire advantages over other cells of the population, then a population of mutant cells is formed and all acquired properties are inherited. If the mutation does not give the cell an advantage, then the mutant cells, as a rule, die.
Transformation. Cells that are able to accept the DNA of another cell during the transformation process are called competent.
Transduction is the transfer of genetic information (DNA) from a donor bacterium to a recipient bacterium with the participation of a bacteriophage. Temperate phages mainly have transducing properties. When multiplying in a bacterial cell, phages incorporate part of the bacterial DNA into their DNA and transfer it to the recipient.
There are three types of transduction: general, specific and abortive.
1 . General transduction is the transfer of various genes localized on different parts of the bacterial chromosome.
At the same time, donor bacteria can transfer various characteristics and properties to the recipient - the ability to form new enzymes, resistance to drugs, etc.
2. Specific transduction is the transfer by phage of only some specific genes localized in special regions of the bacterial chromosome. In this case, only certain characteristics and properties are transmitted.
3. Abortive transduction - transfer by phage of one fragment of the donor chromosome. Usually this fragment is not included in the chromosome of the recipient cell, but circulates in the cytoplasm. When a recipient cell divides, this fragment is transferred to only one of the two daughter cells, and the second cell receives the unchanged recipient chromosome.
With the help of transducing phages, a whole range of properties can be transferred from one cell to another, such as the ability to form a toxin, spores, flagella, produce additional enzymes, drug resistance, etc.
Conjugation is the transfer of genetic material from one bacterium to another through direct cell contact. Cells that transmit genetic material are called donors, and cells that receive it are called recipients. This process is one-way in nature - from the donor cell to the recipient cell.
The donor bacteria are designated F+ (male type), and the recipient bacteria are designated F- (female type). When F + and F - cells come close together, a cytoplasmic bridge appears between them. The formation of the bridge is controlled by factor F (Fertility). This factor contains genes responsible for the formation of sex pili. The donor function can only be performed by those cells that contain factor F. The recipient's cells lack this factor. During crossing, factor F is transferred from the donor cell to the recipient. Having received factor F, the female cell itself becomes a donor (F +).
The conjugation process can be interrupted mechanically, for example by shaking. In this case, the recipient receives incomplete information contained in the DNA.
Conjugation, like other types of recombination, can occur not only between bacteria of the same species, but also between bacteria different types. In these cases, recombination is called interspecific.
Plasmids are relatively small extrachromosomal DNA molecules bacterial cell. They are located in the cytoplasm and have a ring structure. Plasmids contain several genes that function independently of the genes contained in chromosomal DNA.
Prophages that cause a number of changes in a lysogenic cell that are inherited, for example, the ability to form a toxin (see transduction).
F-factor, which is in an autonomous state and takes part in the process of conjugation (see conjugation).
R-factor, which gives the cell resistance to drugs (R-factor was first isolated from Escherichia coli, then from Shigella). Studies have shown that the R factor can be removed from the cell, which is generally typical for plasmids.
K-factor has intraspecific, interspecific and even intergeneric transmissibility, which can cause the formation of atypical strains that are difficult to diagnose.
Bacteriocinogenic factors (col factors), which were first discovered in the culture of Escherichia coli (E. coli), are therefore called colicins. Later they were identified in other bacteria: Vibrio cholerae - Vibriocinae, staphylococci - Staphylocinae, etc.
The Co l factor is a small autonomous plasmid that determines the synthesis of protein substances that can cause the death of bacteria of their own species or closely related ones. Bacteriocins are adsorbed on the surface of sensitive cells and cause metabolic disturbances, which leads to cell death.
Under natural conditions, only a few cells in a population (1 in 1000) spontaneously produce colicin. However, with certain influences on the culture (treatment of bacteria with UV rays), the number of colicin-producing cells increases.
PRACTICAL SIGNIFICANCE OF VARIABILITY OF microorganisms
Pasteur artificially obtained irreversible changes in the causative agents of rabies and anthrax and prepared vaccines that protect against these diseases. Subsequent research in the field of genetics and variability of microorganisms made it possible to obtain a large number of bacterial and viral strains used to produce vaccines.
The results of studies of the genetics of microorganisms were successfully used to clarify the patterns of heredity of higher organisms.
It is also of great scientific and practical importance new section genetics - genetic engineering.
Methods genetic engineering allow you to change the structure of genes and include genes of other organisms responsible for the synthesis of important and necessary substances into the bacterial chromosome. As a result, microorganisms become producers of substances, the production of which by chemical means is a very difficult and sometimes even impossible task. This method is currently used to produce such medications as insulin, interferon, etc. Using mutagenic factors and selection, antibiotic-producing mutants have been obtained that are 100-1000 times more active than the original ones.
9. Genetics of immunity
Genetic determination of the immune response of higher animals
Mechanism of monospecific antibody synthesis and immune memory
Heritability of the level of the body's immune response and the possibility of selecting animals for resistance to infections.
Immunity is the body’s immunity to infectious agents and genetically foreign substances of an antigenic nature. The main function of immunity is immunological surveillance of the internal constancy (homeostasis) of the body.
The consequence of this function is the recognition and then blocking, neutralization or destruction of genetically foreign substances (viruses, bacteria, cancer cells, etc.). The body’s immune system, the totality of all lymphoid cells (a specific protective factor), is responsible for preserving genetically determined biological individuality. Nonspecific protective factors include skin and mucous membranes. Immune response, or immunological reactivity, is a form of the body’s reactions to foreign substances (antigens). The main function of antibodies is their ability to quickly react with an antigen in the form of glutination, precipitation, lysis, and neutralization reactions.
10. Blood groups and biochemical polymorphism.
Concept of blood groups
Heritability of blood groups
Practical application of blood groups in animal husbandry
Polymorphic protein systems and their relationship with animal productivity
Methods for determining blood groups and polymorphic protein systems.
Blood groups were discovered in 1900 (in humans) and explained in 1924. And in 1936 the term immunogenetics was used. Within a species, individuals differ in a number of chemical, genetically determined characteristics that can be detected immunogenetically in the form of antigens (genetically foreign substances that, when introduced into the body, cause immunogenetic reactions). Antibodies are immunoglobulins (proteins) formed in the body under the influence of antigens; differences in blood group are determined by antigens located on the surface of red blood cells. Antigenic factors are sometimes called blood factors, and the sum of all blood groups of one individual is called the blood type. After birth, the blood type of animals does not change. Genetic systems of blood groups and antigens are designated in upper and lowercase letters - A, B, C, etc. There are many antigens, so they are written with the symbols A, B, C, and with subscripts A1, A2, etc.
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GENOTYPICAL (INHERITABLE) VARIATION
Genotypic variation can result from mutations and genetic recombinations.
Mutations (from the Latin mutatio - to change) are inherited structural changes in genes.
Large mutations (genomic rearrangements) are accompanied by loss or changes in relatively large sections of the genome; such mutations are usually irreversible.
Small (point) mutations are associated with the loss or addition of individual DNA bases. In this case, only a small number of characteristics change. Such altered bacteria can completely return to their original state (revert).
Bacteria with altered characteristics are called mutants. Factors that cause the formation of mutants are called mutagens.
Bacterial mutations are divided into spontaneous and induced. Spontaneous (spontaneous) mutations occur under the influence of uncontrollable factors, i.e. without experimenter intervention. Induced (directed) mutations appear as a result of the treatment of microorganisms with special mutagens (chemicals, radiation, temperature, etc.).
As a result of bacterial mutations, the following may occur:
a) change in morphological properties
b) change in cultural properties
c) the emergence of drug resistance in microorganisms
d) loss of the ability to synthesize amino acids, utilize carbohydrates and other nutrients
e) weakening of pathogenic properties, etc.
If a mutation leads to the fact that mutagenic cells acquire advantages over other cells of the population, then a population of mutant cells is formed, and all acquired properties are inherited. If the mutation does not give the cell an advantage, then the mutant cells, as a rule, die. Genetic recombinations. Transformation. Cells that are able to accept the DNA of another cell during the transformation process are called competent. The state of competence often coincides with the logarithmic phase of growth.
Transduction is the transfer of genetic information from a donor bacterium to a recipient bacterium with the participation of a bacteriophage. Temperate phages mainly have transducing properties. When multiplying in a bacterial cell, phages incorporate part of the bacterial DNA into their DNA and transfer it to the recipient. There are three types of transduction: general, specific and abortive.
1. General transduction is the transfer of various genes localized on different parts of the bacterial chromosome. At the same time, donor bacteria can transfer various characteristics and properties to the recipient - the ability to form new enzymes, drug resistance, etc.
2. Specific transduction is transmission
a phage of only some specific genes localized on special sections of the bacterial chromosome. In this case, only certain characteristics and properties are transmitted.
3. Abortive transduction - transfer by phage of one enzyme from the donor chromosome. Usually this fragment is not included in the chromosome of the recipient cell, but circulates in the cytoplasm. When the recipient cell divides, this fragment is transferred to only one of the two daughter cells, and the second cell receives the unchanged recipient chromosome.
With the help of transducing phages, a whole range of properties can be transferred from one cell to another, such as the ability to form a toxin, spores, flagella, produce additional enzymes, drug resistance, etc.
Conjugation is the transfer of genetic material from one bacterium to another through direct cell contact. Cells that transmit genetic material are called donors, and cells that receive it are called recipients. This process is one-way in nature - from the donor cell to the recipient cell.
The donor bacteria are designated F+ (male type), and the recipient bacteria are designated F- (female type). When F+ and F- cells come close together, a cytoplasmic bridge appears between them. The formation of the bridge is controlled by factor F (from the English fertility - fertility). This factor contains genes responsible for the formation of sex villi (sex-pili). The donor function can only be performed by those cells that contain factor F. Recipient cells lack this factor. During crossing, factor F is transferred from the donor cell to the recipient. Having received factor F, the female cell itself becomes a donor (F+).
The conjugation process can be interrupted mechanically, for example by shaking. In this case, the recipient receives incomplete information contained in the DNA.
Transfer genetic information by conjugation is best studied in enterobacteria.
Conjugation, like other types of recombination, can occur not only between bacteria of the same species, but also between bacteria of different species. In these cases, recombination is called interspecific.
Genotypic variability is heritable
Plasmids are relatively small extrachromosomal DNA molecules of a bacterial cell. They are located in the cytoplasm and have a ring structure. Plasmids contain several genes that function independently of the genes contained in chromosomal DNA.
Fig.54 Plasmids (extrachromosomal DNA molecules)
A typical feature of plasmids is their ability to reproduce independently (replicate).
They can also move from one cell to another and include new genes from environment. Plasmids include:
Prophages. causing a number of changes in a lysogenic cell that are inherited, for example the ability to form a toxin (see transduction). F-factor, which is in an autonomous state and takes part in the process of conjugation (see conjugation).
R-factor, which gives the cell resistance to drugs (R-factor was first isolated from Escherichia coli, then from Shigella). Studies have shown that the R factor can be removed from the cell, which is generally typical for plasmids.
The R-factor has intraspecific, interspecific and even intergeneric transmissibility, which can cause the formation of atypical strains that are difficult to diagnose.
Bacteriocinogenic factors (col factors), which were first discovered in the culture of Escherichia coli (E. coli), are therefore called colicins. Subsequently, they were identified in other bacteria: Vibrio cholerae - vibriocins, staphylococci - staphylocins, etc.
Col factor is a small autonomous plasmid that determines the synthesis of protein substances that can cause the death of bacteria of their own species or closely related ones. Bacteriocins are adsorbed on the surface of sensitive cells and cause metabolic disturbances, which leads to cell death.
Under natural conditions, only a few cells in a population (1 in 1000) spontaneously produce colicin. However, with certain influences on the culture (treatment of bacteria with UV rays), the number of colicin-producing cells increases.
Changes in functional genes
In mutated cells, mutations can be somatic (for example, different eye colors in one person) and generative (or gametic). Generative mutations are transmitted to offspring, while somatic mutations manifest themselves in the individual. They are inherited only through vegetative propagation.
Based on the outcome (meaning) for the body, mutations are classified as positive, neutral and negative. Positive mutations appear rarely. They increase the vitality of the organism and are important for evolution (for example, mutations leading to the appearance of a four-chambered heart during the evolution of chordates). Neutral mutations have virtually no effect on vital processes (for example, mutations leading to the presence of freckles). Negative mutations are divided into semi-lethal and lethal. Semi-lethal mutations reduce the viability of the organism and shorten its lifespan (for example, mutations leading to Down's disease). Lethal mutations cause
death of the body before birth or at the time of birth (for example, mutations leading to the absence of a brain).
According to the change in phenotype, mutations can be morphological (for example, reduced eyeballs, six fingers on the hand) and biochemical (for example, albinism, hemophilia).
Based on changes in the genotype, mutations are distinguished into genomic, chromosomal and gene mutations.
Genomic mutations are changes in the number of chromosomes under the influence of environmental factors. Haploidy is a set of chromosomes 1n. In nature, it is found in drones (male) bees. The viability of such organisms is reduced, since all recessive genes appear in them.
Polyploidy is an increase in the haploid number of chromosomes (3n, 4n, 5n). Polyploidy is used in plant growing. It leads to increased productivity. For humans, haploidy and polyploidy are lethal mutations.
Aneuploidy is a change in the number of chromosomes in individual pairs (2n±1, 2n±2, and so on).
Trisomy. for example, if an X chromosome is added to a pair of sex chromosomes in a female body, trisomy X syndrome (47, XXX) develops; if it is added to the sex chromosomes of a male body, Klinefelter syndrome (47, XXY) develops. Monosomy. absence of one chromosome in a pair – 45, X0 – Shereshevsky-Turner syndrome. Nulisomy. absence of a pair of homologous chromosomes (for humans - a lethal mutation).
Chromosomal mutations (or chromosomal aberrations) are changes in the structure of chromosomes (interchromosomal or intrachromosomal). Rearrangements within one chromosome are called inversions, deficiencies (deficiencies and deletions), and duplications. Interchromosomal rearrangements are called translocations.
Examples: deletion – cry-the-cat syndrome in humans; duplication – the appearance of strip-shaped eyes in Drosophila; inversion – change in the order of genes.
Translocations can be: reciprocal - two chromosomes exchange segments; non-reciprocal - segments of one chromosome are transferred to another Robertsonian - two acrocentric chromosomes are connected by their centromeric sections.
Deficiencies and duplications always manifest themselves phenotypically, as the set of genes changes. Inversions and translocations do not always appear. In these cases, the conjugation of homologous chromosomes becomes difficult and the distribution of genetic material between daughter cells is disrupted.
Gene mutations are called point mutations, or transgenations. They are associated with changes in gene structure and cause the development of metabolic diseases (their frequency is 2-4%).
Changes in structural genes.
1. A reading frame shift occurs when one or more nucleotide pairs are dropped or inserted into a DNA molecule.
2. Transition - a mutation in which a purine base is replaced by a purine base or a pyrimidine base by a pyrimidine base (A G or C T). This replacement leads to a change in codons.
3. Transversion - replacement of a purine base with a pyrimidine or a pyrimidine with a purine (A C G T) - leads to a change in codons. Changing the meaning of codons leads to missense mutations. If nonsense codons are formed (UAA, UAG, UGA), they cause nonsense mutations. These codons do not specify amino acids, but are terminators - they determine the end of the information reading.
1. The repressor protein has been changed; it does not fit the operator gene. In this case, structural genes do not turn off and work constantly.
2. The repressor protein is tightly attached to the operator gene and is not “removed” by the inducer. Structural genes don't work all the time.
3. Violation of the alternation of the processes of repression and induction. If the inducer is absent, the specific protein is synthesized; in the presence of the inducer, it is not synthesized. Such disruptions in the functioning of transcriptons are observed with mutations in the regulator gene or operator gene.
Currently, about 5,000 metabolic diseases caused by gene mutations have been described. Examples of these include phenylketonuria, albinism, galactosemia, various hemophilias, sickle cell anemia, achondroplasia, etc.
In most cases, gene mutations manifest themselves phenotypically.
Heredity and variability. Chromosomal theory of heredity
Heredity is the most important feature of living organisms, which consists in the ability to transmit the properties and functions of parents to offspring. This transmission is carried out using genes.
A gene is a unit of storage, transmission and implementation of hereditary information. A gene is a specific section of a DNA molecule, the structure of which encodes the structure of a specific polypeptide (protein). It is likely that many sections of DNA do not code for proteins, but perform regulatory functions. In any case, in the structure of the human genome, only about 2% of DNA are sequences on the basis of which messenger RNA is synthesized (transcription process), which then determines the sequence of amino acids during protein synthesis (translation process). It is currently believed that there are about 30 thousand genes in the human genome.
Genes are located on chromosomes, which are located in the nucleus of cells and are giant DNA molecules.
Chromosome theory heredity was formulated in 1902 by Setton and Boveri. According to this theory, chromosomes are carriers of genetic information that determines the hereditary properties of the organism. In humans, each cell has 46 chromosomes, divided into 23 pairs. Chromosomes that form a pair are called homologous.
Sex cells (gametes) are formed using a special type of division - meiosis. As a result of meiosis, only one homologous chromosome from each pair remains in each sex cell, i.e. 23 chromosomes. Such a single set of chromosomes is called haploid. During fertilization, when the male and female reproductive cells fuse and form a zygote, the double set, which is called diploid, is restored. In a zygote, in the organism that develops from it, one chromosome from each chromosome is received from the paternal organism, the other from the maternal.
A genotype is a set of genes received by an organism from its parents.
Another phenomenon that genetics studies is variability. Variability is understood as the ability of organisms to acquire new characteristics - differences within a species. There are two forms of variability:
- hereditary
- modification (non-hereditary).
Hereditary variability is a form of variability caused by changes in the genotype, which can be associated with mutational or combinational variability.
Mutational variability.
Genes undergo changes from time to time, which are called mutations. These changes are random and appear spontaneously. The causes of mutations can be very diverse. There are a number of factors that increase the likelihood of a mutation occurring. This may be exposure to certain chemicals, radiation, temperature, etc. Using these means, mutations can be caused, but the random nature of their occurrence remains, and it is impossible to predict the appearance of a particular mutation.
The resulting mutations are passed on to descendants, i.e. they determine hereditary variability, which is associated with where the mutation occurred. If a mutation occurs in a reproductive cell, then it has the opportunity to be transmitted to descendants, i.e. be inherited. If the mutation occurs in a somatic cell, then it is transmitted only to those that arise from this somatic cell. Such mutations are called somatic; they are not inherited.
There are several main types of mutations.
- Gene mutations, in which changes occur at the level of individual genes, i.e. sections of the DNA molecule. This may be the waste of nucleotides, the replacement of one base with another, the rearrangement of nucleotides, or the addition of new ones.
- Chromosomal mutations associated with disruption of chromosome structure lead to serious changes that can be detected using a microscope. Such mutations include losses of chromosome sections (deletions), addition of sections, rotation of a chromosome section by 180°, and the appearance of repeats.
- Genomic mutations are caused by changes in the number of chromosomes. Extra homologous chromosomes may appear: in the chromosome set, trisomy appears in place of two homologous chromosomes. In the case of monosomy, there is a loss of one chromosome from a pair. With polyploidy, there is a multiple increase in the genome. Another variant of genomic mutation is haploidy, in which only one chromosome from each pair remains.
The frequency of mutations is influenced, as already mentioned, by a variety of factors. When a number of genomic mutations occur great importance has, in particular, the age of the mother.
Combinative variability.
This type of variability is determined by the nature of the sexual process. With combinative variation, new genotypes arise due to new combinations of genes. This type of variability manifests itself already at the stage of formation of germ cells. As already mentioned, in each sex cell (gamete) there is only one homologous chromosome from each pair. Chromosomes enter the gamete randomly, so the sex cells of one person can differ quite greatly in the set of genes on the chromosomes. An even more important stage for the emergence of combinative variability is fertilization, after which the newly emerged organism has 50% of its genes inherited from one parent and 50% from the other.
Modifying variability is not associated with changes in the genotype, but is caused by the influence of the environment on the developing organism.
The presence of modification variability is very important for understanding the essence of inheritance. Traits are not inherited. You can take organisms with absolutely the same genotype, for example, grow cuttings from the same plant, but place them in different conditions (lighting, humidity, mineral nutrition) and get quite different plants with different characteristics (growth, yield, leaf shape and so on.). To describe the actually formed characteristics of an organism, the concept of “phenotype” is used.
A phenotype is the entire complex of actually occurring characteristics of an organism, which is formed as a result of the interaction of the genotype and environmental influences during the development of the organism. Thus, the essence of inheritance lies not in the inheritance of a trait, but in the ability of a genotype to produce a certain phenotype as a result of interaction with developmental conditions.
Since modification variability is not associated with changes in the genotype, modifications are not inherited. Usually this position is difficult to accept for some reason. It seems that if, say, parents have trained in lifting weights for several generations and have developed muscles, then these properties must necessarily be passed on to their children. Meanwhile, this is a typical modification, and training is the environmental influence that influenced the development of the trait. No changes in the genotype occur during modification and the characteristics acquired as a result of modification are not inherited. Darwin called this type of variability non-hereditary.
To characterize the limits of modification variability, the concept of reaction norm is used. Some characteristics in humans cannot be changed due to environmental influences, for example, blood type, gender, eye color. Others, on the contrary, are very sensitive to environmental influences. For example, as a result of prolonged exposure to the sun, skin color becomes darker and hair becomes lighter. A person’s weight is greatly influenced by diet, illness, and the presence of bad habits, stress, lifestyle.
Environmental influences can lead not only to quantitative, but also to qualitative changes in the phenotype. In some species of primrose, red flowers appear at low air temperatures (15-20 C), but if the plants are placed in a humid environment with a temperature of 30 ° C, white flowers are formed.
Moreover, although the reaction norm characterizes a non-hereditary form of variability (modification variability), it is also determined by the genotype. This point is very important: the reaction rate depends on the genotype. The same environmental impact on a genotype can lead to a strong change in one of its traits and not affect another.
21. A gene is a functional unit of heredity. Molecular structure gene in prokaryotes and eukaryotes. Unique genes and DNA repeats. Structural genes. The “1 gene - 1 enzyme” hypothesis, its modern interpretation.
A gene is a structural and functional unit of heredity that controls the development of a certain trait or property. Parents pass on a set of genes to their offspring during reproduction. The term "gene" was coined in 1909 by the Danish botanist Vilhelm Johansen. The study of genes is the science of genetics, the founder of which is considered to be Gregor Mendel, who in 1865 published the results of his research on the inheritance of traits when crossing peas. Genes can undergo mutations - random or targeted changes in the sequence of nucleotides in the DNA chain. Mutations can lead to a change in the sequence, and therefore a change in the biological characteristics of a protein or RNA, which, in turn, can result in a general or local altered or abnormal functioning of the body. Such mutations in some cases are pathogenic, since they result in disease, or lethal at the embryonic level. However, not all changes in the nucleotide sequence lead to changes in the protein structure (due to the degeneracy effect genetic code) or to a significant change in sequence and are not pathogenic. In particular, the human genome is characterized by single nucleotide polymorphisms and copy number variations, such as deletions and duplications, which account for about 1% of the total human nucleotide sequence. Single nucleotide polymorphisms, in particular, define different alleles of a single gene.
In humans, as a result of deletion:
Wolf syndrome - a region is lost on large chromosome 4,
“Cry of the cat” syndrome - with a deletion in chromosome 5. Cause: chromosomal mutation, loss of a chromosome fragment in the 5th pair.
Manifestation: abnormal development of the larynx, cat-like cries in early childhood, retardation in physical and mental development.
The monomers that make up each DNA strand are complex organic compounds, including nitrogenous bases: adenine (A) or thymine (T) or cytosine (C) or guanine (G), pentaatomic sugar-pentose-deoxyribose, after which the DNA itself was named, as well as the residue phosphoric acid. These compounds are called nucleotides.
The chromosome of any organism, be it a bacterium or a human, contains a long, continuous strand of DNA. along which many genes are located. Different organisms differ dramatically in the amount of DNA that makes up their genomes. In viruses, depending on their size and complexity, the genome size ranges from several thousand to hundreds of nucleotide pairs. Genes in such simply arranged genomes are located one after another and occupy up to 100% of the length of the corresponding nucleic acid(RNA and DNA). For many viruses, the complete DNA nucleotide sequence has been established. Bacteria have a much larger genome size. E. coli has a single strand of DNA - the bacterial chromosome consists of 4.2x106 (degree 6) nucleotide pairs. More than half of this amount consists of structural genes, i.e. genes encoding certain proteins. The rest of the bacterial chromosome consists of nucleotide sequences that cannot be transcribed, the function of which is not entirely clear. The vast majority of bacterial genes are unique, i.e. presented once in the genome. The exception is the genes for transport and ribosomal RNAs, which can be repeated dozens of times.
The genome of eukaryotes, especially higher ones, sharply exceeds the size of the genome of prokaryotes and, as noted, reaches hundreds of millions and billions of nucleotide pairs. The number of structural genes does not increase very much. The amount of DNA in the human genome is sufficient to form approximately 2 million structural genes. The actual number is estimated at 50-100 thousand genes, i.e. 20-40 times less than what could be encoded by a genome of this size. Consequently, we have to admit the redundancy of the eukaryotic genome. The reasons for redundancy have now become largely clear: firstly, some genes and nucleotide sequences are repeated many times, secondly, there are many genetic elements in the genome that have a regulatory function, and thirdly, part of the DNA does not contain genes at all.
According to modern ideas, a gene encoding the synthesis of a specific protein, in eukaryotes consists of several essential elements. First of all, this is an extensive regulatory zone that has a strong influence on the activity of the gene in a particular tissue of the body at a certain stage of its individual development. Next, directly adjacent to the coding elements of the gene, there is a promoter - a DNA sequence up to 80-100 nucleotide pairs long, responsible for binding the RNA polymerase that transcribes the gene. Following the promoter lies the structural part of the gene, which contains information about primary structure the corresponding protein. For most eukaryotic genes, this region is significantly shorter than the regulatory zone, but its length can be measured in thousands of nucleotide pairs.
An important feature of eukaryotic genes is their discontinuity. This means that the protein-coding region of the gene consists of two types of nucleotide sequences. Some - exons - are sections of DNA that carry information about the structure of a protein and are part of the corresponding RNA and protein. Others - introns - do not encode the structure of the protein and are not part of the mature mRNA molecule, although they are transcribed. The process of cutting out introns - “unnecessary” sections of the RNA molecule and splicing exons during the formation of mRNA is carried out by special enzymes and is called Splicing (crosslinking, splicing).
The eukaryotic genome is characterized by two main features:
1) Repetition of sequences
2) Division by composition into various fragments characterized by a specific nucleotide content
Repeated DNA consists of nucleotide sequences of varying length and composition that occur several times in the genome, either in tandem repeated or dispersed form. DNA sequences that are not repeated are called unique DNA. The size of the portion of the genome occupied by repetitive sequences varies widely between taxa. In yeast it reaches 20%, in mammals up to 60% of all DNA is repeated. In plants, the percentage of repeated sequences can exceed 80%.
According to the mutual orientation in the DNA structure, direct, inverted, symmetric repeats, palindromes, complementary palindromes, etc. are distinguished. The length (in number of bases) of an elementary repeating unit, the degree of their repeatability, and the nature of distribution in the genome vary over a very wide range. The periodicity of DNA repeats can have a very complex structure, when short repeats are included in longer ones or border them, etc. In addition, mirror and inverted repeats can be considered for DNA sequences. The human genome is 94% known. Based on this material, the following conclusion can be drawn: repeats occupy at least 50% of the genome.
STRUCTURAL GENES - genes encoding cellular proteins with enzymatic or structural functions. These also include genes encoding the structure of rRNA and tRNA. There are genes that contain information about the structure of the polypeptide chain, and ultimately, structural proteins. Such sequences of nucleotides one gene long are called structural genes. Genes that determine the place, time, and duration of activation of structural genes are regulatory genes.
Genes are small in size, although they consist of thousands of nucleotide pairs. The presence of a gene is established by the manifestation of the gene trait (the final product). General scheme The structure of the genetic apparatus and its work were proposed in 1961 by Jacob and Monod. They proposed that there is a section of a DNA molecule with a group of structural genes. Adjacent to this group is a region of 200 nucleotide pairs - the promoter (the site adjacent to the DNA-dependent RNA polymerase). This region is adjacent to the operator gene. The name of the entire system is operon. Regulation is carried out by a regulatory gene. As a result, the repressor protein interacts with the operator gene, and the operon begins to work. The substrate interacts with the gene with regulators, the operon is blocked. Principle feedback. Expression of the operon is incorporated as a whole. 1940 - Beadle and Tatum proposed a hypothesis: 1 gene - 1 enzyme. This hypothesis played an important role - scientists began to consider the final products. It turned out that the hypothesis has limitations, because All enzymes are proteins, but not all proteins are enzymes. Typically, proteins are oligomers - i.e. exist in a quaternary structure. For example, the tobacco mosaic capsule has more than 1200 polypeptides. In eukaryotes, gene expression (manifestation) has not been studied. The reason is serious obstacles:
Organization of genetic material in the form of chromosomes
U multicellular organisms cells are specialized and therefore some genes are turned off.
The presence of histone proteins, while prokaryotes have “naked” DNA.
Histone and non-histone proteins take part in gene expression and participate in the creation of structure.
22. Classification of genes: structural genes, regulators. Properties of genes (discreteness, stability, lability, polyallelicity, specificity, pleiotropy).
Discreteness - immiscibility of genes
Stability - the ability to maintain structure
Lability - the ability to mutate repeatedly
Multiple allelism - many genes exist in a population in multiple molecular forms
Allelicity - in the genotype of diploid organisms there are only two forms of the gene
Specificity - each gene encodes its own trait
Pleiotropy - multiple gene effect
Expressiveness - the degree of expression of a gene in a trait
Penetrance - frequency of manifestation of a gene in a phenotype
Amplification is an increase in the number of copies of a gene.
23. Gene structure. Regulation of gene expression in prokaryotes. Operon hypothesis.
Gene expression is the process by which hereditary information from a gene (DNA nucleotide sequence) is converted into a functional product - RNA or protein. Gene expression can be regulated at all stages of the process: during transcription, during translation, and at the stage of post-translational modifications of proteins.
Regulation of gene expression allows cells to control their own structure and function and is the basis of cell differentiation, morphogenesis and adaptation. Gene expression is a substrate for evolutionary change, since control over the timing, location, and quantity of expression of one gene can have an impact on the functions of other genes throughout the organism. In prokaryotes and eukaryotes, genes are sequences of DNA nucleotides. Transcription occurs on the DNA matrix - the synthesis of complementary RNA. Next, translation occurs on the mRNA matrix - proteins are synthesized. There are genes encoding non-messenger RNA (eg, rRNA, tRNA, small RNA) that are expressed (transcribed) but not translated into proteins.
Studies on E. coli cells have revealed that bacteria have 3 types of enzymes:
constitutive, present in cells in constant quantities regardless of the metabolic state of the body (for example, glycolytic enzymes)
inducible, their concentration under normal conditions is low, but can increase 100Q times or more if, for example, a substrate of such an enzyme is added to the cell culture medium
repressed, i.e. enzymes of metabolic pathways, the synthesis of which stops when the end product of these pathways is added to the growing medium.
Based on genetic studies of the induction of β-galactosidase, which is involved in E. coli cells, in the hydrolytic breakdown of lactose, Francois Jacob and Jacques Monod in 1961 formulated the operon hypothesis, which explained the mechanism of control of protein synthesis in prokaryotes.
In experiments, the operon hypothesis was fully confirmed, and the type of regulation proposed in it began to be called control of protein synthesis at the transcription level, since in this case the change in the rate of protein synthesis is carried out due to changes in the rate of gene transcription, i.e. at the stage of mRNA formation.
In E. coli, like other prokaryotes, DNA is not separated from the cytoplasm by a nuclear envelope. During the transcription process, primary transcripts are formed that do not contain nitrones, and mRNAs lack a “cap” and a poly-A end. Protein synthesis begins before the synthesis of its matrix ends, i.e. transcription and translation occur almost simultaneously. Based on the genome size (4 × 106 base pairs), each E. coli cell contains information about several thousand proteins. But when normal conditions growth, it synthesizes about 600-800 different proteins, which means that many genes are not transcribed, i.e. inactive. Protein genes whose functions in metabolic processes are closely related are often grouped together in the genome into structural units (operons). According to the theory of Jacob and Monod, operons are sections of the DNA molecule that contain information about a group of functionally interrelated structural proteins and a regulatory zone that controls the transcription of these genes. The structural genes of an operon are expressed consistently, either they are all transcribed, in which case the operon is active, or none of the genes are “read,” in which case the operon is inactive. When an operon is active and all its genes are transcribed, a polycistronic mRNA is synthesized, which serves as a template for the synthesis of all proteins of this operon. Transcription of structural genes depends on the ability of RNA polymerase to bind to the promoter located at the 5" end of the operon before the structural genes.
The binding of RNA polymerase to the promoter depends on the presence of a repressor protein in a region adjacent to the promoter, which is called the “operator”. The repressor protein is synthesized in the cell with constant speed and has an affinity for the operator site. Structurally, the promoter and operator regions partially overlap, so the attachment of the repressor protein to the operator creates a steric hindrance for the attachment of RNA polymerase.
Most mechanisms regulating protein synthesis are aimed at changing the rate of binding of RNA polymerase to the promoter, thus influencing the stage of transcription initiation. Genes that synthesize regulatory proteins can be removed from the operon whose transcription they control.
A group of Russian researchers, Peter Garyaev, managed to use the modulation method to prove that it is possible to restore chromosomes damaged by X-ray radiation. Biophysicists have even been able to isolate information patterns from one DNA and superimpose them on another. Thus, they reprogrammed the cells of the second organism in the image of the first genome. Scientists are reported to have successfully transformed frog embryos into salamander embryos simply by irradiating them with waves that carried information patterns corresponding to other DNA. In other words, they rewrote the program and changed the waveform of the animal's body.
All this was done only by superimposing sound vibrations of specially selected words on a laser beam, and not by the outdated procedure of cutting out genes. This experiment scientifically explains "magic" when a magician uses a spell to transform one animal into another. However, scientists from Peter Garyaev’s group were far from the first to conduct successful experiments in DNA reprogramming.
For example, at the very beginning of the 60s of the last century, the Chinese researcher Jiang Kanzhen experimentally became convinced that all living beings emit energy that controls all processes in their bodies. cellular level. This energy contains all the information about his genetic code. And if a creature of another species comes into the zone of action of psychic energy, then the DNA of this creature changes. This is what Jiang Kanzhen writes about the amazing experiences Vladimir Babanin in his book “Time Machines”:
“The enhanced flow of psychic energy emerging through the top of the pyramid could be used for medicinal purposes, to change the code of DNA genes... No, this is not the fantasy of the author of this book. This discovery was made in the 60s of the twentieth century by Chinese medical scientist Jiang Kanzhen. As you know, in modern radio engineering all kinds of waveguides are widely used, with the help of which you can direct radiation energy or a signal, like water from a fire hose, in the desired direction. Previously, they were mainly metal tubes with a round or rectangular cross-section. Now other materials, including non-metallic ones, are also used as waveguides. Interest Ask : if light, acoustic, radio and other waves can be sent along a waveguide, then is it possible to send psychic energy with extremely high frequencies along it? Could waves of psychic energy be to some extent subject to the known laws of physics, refraction and reflection? A strange question... After all, psychic energy is more subtle than the microwave radio waves we know. Moreover, it is all-pervasive. But it has outstanding abilities for creativity and transformation into other types of energy, and therefore can manifest itself differently in different conditions. This will be clearly noticeable when a person masters the mental powers of his body. He will be subject to gravitational energy and will be able to fly. Electromagnetic energy will obey him, and he will be able to send striking lightning. He will be able to change the course of time and move to other, parallel worlds... Starships will be built on the same principle - vortex ships that will overcome space and time. And all these are the possibilities of psychic energy, its enormous ability to transform and manifest itself in other types of energy. So, can the psychic energy emitted through the top of the pyramids or emitted by the body of a living being be directed into a waveguide and used at its discretion? We should try... This is where Chinese medical researcher Jiang Kanzhen made his presence known. Already at the very beginning of the 60s of the 20th century, he was experimentally convinced that all living beings emit energy that controls all processes in their body at the cellular level and contains all the information about its genetic code. And if a growing embryo of a creature of another species came into the zone of action of this energy, then changes occurred at the genetic level! The result was a composite creature - the sphinx. Thus, by “irradiating” a chicken embryo developing in a chicken egg with the energy field of a duck’s body, a chicken duck was obtained. It contained signs of both chicken and duck. And this is without surgical intervention in the DNA of the chicken egg embryo! Then experiments were carried out on other animals and new sphinx monsters were created. When the first article with the results of the experiments was published in 1963, it produced the effect of an exploding bomb in China. Only a few scientists expressed their admiration for this discovery and saw in it the future of genetic engineering that could transform the world. Other scientists and, accordingly, the public had a different opinion. They saw in the discovery a threat to the evolution of humanity and the animal world, the possibility of creating psychotronic weapons capable of subjugating a person in the interests of ambitious people, remaking his nature. In the end, no one wanted to end up as a chicken duck, a saber-toothed monster, or some other sphinx as a result of someone’s experiments. The reaction was immediate: research laboratories were closed. The powerful wave of the cultural revolution that swept China at that time put a barrier to further research. Jiang was sent to a village for re-education, where he tended pigs, and after attempting to escape, he was sent to prison, where he spent several years. And only in 1971 he secretly crossed the Soviet-Chinese border and settled in Khabarovsk, where he later became an employee of the medical institute. By a strange coincidence, he himself became a “composite” Russian-Chinese: his surname Jiang Kanzhen remained Chinese, but his first and patronymic became Russian: Yuri Vladimirovich. Soviet scientists subsequently became interested in Jiang's discovery and continued their research in this direction. What are the results? They are very important, but they do not become public knowledge. We are now interested in how, with the help of what technical means, Jiang managed to concentrate and transmit psychic energy in a strictly defined direction, and what he used it for. From the outside, its entire design seemed quite simple. In one of the rooms there was a spacious closed volumetric circuit chamber made of a non-magnetic material - sheet copper. Several hollow copper cones are soldered into the walls of the chamber with a bell inside - analogues of pyramid cap models. The tops of the cones are cut off, and long thin copper tubes - waveguides - are soldered to them. They stretched into the next room and ended in another volumetric contour chamber. That's the whole structure. As we understand, the first chamber with its outer cones was modeled in principle as an ordinary pyramid with a cut off top and a chamber inside. How then did this strange installation work? In the first chamber - the "pyramid" - there was a "donor" - a "generator" of psychic energy. There was no need to invent any technical means that would generate waves of psychic energy. Yes, this is difficult at our level of scientific development. The best generator of psychic energy was a living creature - a person, animal or plant. Their aura—an energy-information field—was the carrier and source of this energy. It contained all the information about the processes occurring in a living organism at the cellular level, about the signals and commands to which the cells obeyed. These commands and programs of all processes of one organism were to be transmitted via “bio-microwave communication” to another organism located at a distance. The cones in the installation served as pyramids. The vortex flow inside them seemed to “suck in” the energy of a living being—the “donor”—and directed it into the waveguide, and along it into another chamber. It contained a living object of the same or a different species. He was subject to “irradiation”. He had to accept the commands and orders received and carry them out, even if they destroyed his entire body. Which organism best fulfilled the received, often alien, commands and orders? As the famous Russian breeder I.V. Michurin once noted, a young growing organism adapted best to new conditions. Therefore, in order to obtain a quick effect, growing animal specimens, eggs of birds, snakes, crocodiles with developing embryos, and germinating plant grains could be placed in the second chamber. Under normal, familiar conditions, the embryos of plants and living beings develop in accordance with the genetic program embedded in their cells. But along the waveguide, signals with a different genetic program, even a completely different species of living creature, came from the “donor”. And then a struggle began between the programs, the outcome of which was unpredictable. As a rule, a compromise was found, as a result of which the genetic code of the developing embryo was changed. So in the second chamber a plant or living creature grew, containing the signs of two creatures - the one who was in the first chamber, and the one who was in the second. But it was already a monster, a freak, a sphinx! It would be good if plants were involved in the experiment. But when it came to different types of animals, it was not only not funny, but even criminal, especially when there was a person in one cell and an animal in the other. By the way, Jiang also conducted the following experiments: in the first chamber he himself was the “donor”, and in the second – a chicken egg in an incubator. As a result of irradiation, a chicken grew up, whose body, instead of feathers, was covered with... hair! But it could have been even worse - a bird with a human head. Such creatures are favorite characters in many ancient legends. Perhaps they reflect facts that actually took place as a result of careless experiments by ancient geneticists? And most importantly: the produced sphinxes could reproduce and produce offspring of sphinxes! In fact, Jiang Kanzhen’s installation was a kind of psychotronic generator. As you know, every stick has two ends. Jiang's invention had the same two ends. It is useful, but within acceptable limits: for creating new types of plants that give us food, for treating incurable diseases, for many other purposes that do not cause harm. But it can also pose a great threat to human nature if the capabilities of such a psychotronic generator are used by an individual or groups of people, or even an entire state in political purposes».
Our esoteric and spiritual teachers have long known that the human body can be programmed not only with the help of pyramids, but also with the help of certain sounds, rhyming sentences or concentrated thought. This has now been scientifically proven by DNA researchers and explained
. Of course, DNA reprogramming must be performed at the appropriate frequency, and that is why not every scientist or esotericist is able to constantly obtain equally successful and profound results. The soul embodied in the body must constantly work on its internal processes, it must strive to establish a conscious connection with its DNA and bring it to harmony. For the spiritual consciousness of a person can and should rewrite the DNA program. The same work of DNA reprogramming can be performed by a regular golden section pyramid if a person meditates in it for about one hour every day.
However, the higher a person’s consciousness is developed, the more his mental and spiritual qualities are revealed, the less he feels the need for any external device to reprogram his DNA.
Two years ago, the CRISPR/Cas9 genome modification technology was invented. In 2015, she made a real revolution in genetic engineering. The technology is based on the molecular defense mechanism of microorganisms, thanks to which DNA fragments can be edited and cut out with increased precision. Moreover, this can be done directly in living cells of any organism!
Of course, today manipulation of genes will not surprise anyone, but work with them was previously carried out in specially equipped laboratories at major institutes. But CRISPR/Cas9 technology can become available to everyone. NASA molecular biologist Josiah Zayner intends to develop a kit that would allow experiments with gene modification at home. He will allow him to change the genome of yeast and microorganisms in his kitchen.
How the technology works
The abbreviation CRISPR can be literally translated into Russian as “clustered regularly interspaced short palindromic repeats”; they were first found in the genes of archaea and bacteria. Then it was discovered that microorganisms that managed to survive the attack of the virus inscribe a portion of the enemy’s gene into their own DNA. Thanks to this, the cells formed by the body will be able to recognize such a strain. If the “database” of genes contains information about an enemy, then when they encounter him, microorganisms use a special molecular mechanism. It attaches to the viral DNA in the place that corresponds to the preserved region. Next, Cas group proteins are used to cut it and destroy the virus. Scientists have determined that similar scissors for cutting molecules can be used for any part of the genetic code of mammals, and humans are no exception. With their help, you can replace or edit various genes.
The ODIN online store will begin selling gene code editing kits
According to Mr. Zayner, CRISPR/Cas9 should become publicly available, and even novice researchers and amateurs should be able to conduct experiments with this method. For this purpose, the online store The ODIN was developed. Its goal is to help conduct home experiments with artificially created bacteria. Today, Zayner’s company is raising funds on the Indiegogo crowdfunding platform, offering complete kits and reagents for gene editing as a “reward.”
Available sets
The products sold are similar to educational kits for conducting chemical experiments by schoolchildren and students. For $75, you can buy a kit here that allows you to add a fluorescent protein to the genome of bacteria, causing them to glow in the dark. To create a genetically modified strain of bacteria that can survive in extreme conditions, you need to buy a kit for $130. But a kit for 160 US dollars will allow you to make changes to the gene code of yeast, adding red pigment to it.
The company also offers more expensive sets. For example, for $200 you can get a kit that gives bacteria the ability to fertilize soil and break down plastic. For $500 you can buy a classroom kit - the client can specify the type of kits that will be sent in quantities of 20 for group use. The tools in this set can give bacteria the ability to glow in the dark or change color.
A $3,000 kit will allow you to create a real home laboratory for conducting experiments in molecular and synthetic biology. It includes: centrifuges, pipettes, reagents, electrophoresis gel, chemicals and much more. The kit comes with a set that allows you to use the CRISPR system for various studies.
The most incredible is the offer for $5,000: the authors of the project promise the opportunity to create a new, unique living organism. With its help, you can isolate the desired characteristic of yeast or bacteria and change it. The owner of such a kit can independently breed genetically modified organisms. The company helps you determine the parameters that will help you achieve your goals! Detailed instructions included with each kit will help you carry out experiments without outside help, although the authors readily promise to provide consultation if necessary.
Future plans
CRISPR technology is capable of making changes to human genes. However, Zayner does not plan to sell kits that would help fight baldness or grow an additional kidney.
To achieve his goal, Zayner launched a crowdfunding campaign on the Indiegogo website. You can view the company. Thanks to growing interest in the CRISPR method, the company's authors managed to obtain the $10,000 needed to create portable kits ahead of schedule. According to Investtok.ru experts, by the end of the campaign, the project’s authors can raise ten times more funds than originally planned, since audience interest in new technology huge.
Mutation ( lat. mutatio - change) - a persistent transformation of the genotype that occurs under the influence of the external or internal environment.
Genomic mutations - These are mutations that lead to the addition or loss of one, several or a complete haploid set of chromosomes. Different types of genomic mutations are called heteroploidy and polyploidy.
Polyploidy– multiple changes (several times, for example, 12 → 24). It does not occur in animals; in plants it leads to an increase in size.
Aneuploidy– changes on one or two chromosomes. For example, one extra twenty-first chromosome leads to Down syndrome (the total number of chromosomes is 47)
26.Change in the number and order of genes (chromosomal rearrangements)
Chromosomal rearrangements(also called aberrations) occur when there are two or more chromosomal breaks.
· Deletion, or shortage. A section of a chromosome is lost.
· Duplication, or doubling. One of the chromosome regions is represented more than once in the chromosome set.
· Inversion occurs as a result of two breaks in one chromosome, but provided that the internal fragment of the chromosome rotates 180 degrees, i.e. its polarity will reverse.
The inverted region of the chromosome may or may not include a centromere. In the first case, the inversion is called pericentric(i.e., covering the centromere), and in the second - paracentric(pericentromeric).
Translocations . If breaks occur in two chromosomes, then during reunification an exchange of fragments is possible. With symmetric reunification, new chromosomes are formed in which the distal sections of non-homologous chromosomes have been exchanged. Such translocations are called reciprocal.
A section of a chromosome can also change its position without reciprocal exchange, remaining in the same chromosome or being included in some other one. Such non-reciprocal translocations are sometimes called transpositions .
In the case of the connection of two acrocentric chromosomes in the region of their centromeres with the loss of short arms, a centric fusion is observed - Robertsonian translocation.
27.Change in individual genes (gene mutation)
Mutations(from Latin mutatio - change) is a change in genes and chromosomes, phenotypically manifested in changes in the properties and characteristics of organisms.
Gene (point) mutations- these are changes in the number and/or sequence of nucleotides in the DNA structure (insertions, deletions, movements, substitutions of nucleotides) within individual genes, leading to a change in the quantity or quality of the corresponding protein products.
Transfer of gene mutation.
It occurs according to the usual laws of heredity. The risk to the offspring is more or less great, depending on whether the “sick” gene is dominant or recessive and where it is located - in the regular chromosome or in the sex chromosome. Just keep in mind that if the gene turns out to be recessive, a person can pass it on to his offspring.
A typical example is hemophilia, a blood disease (blood clotting disorder). This disease is different in that it is transmitted only by women, but causes impairment only in men; in other words, a woman who is apparently healthy can pass this disease on to one of her sons.
