Biology is a very voluminous science that covers all aspects of the life of every living being, from the structure of its microstructures inside the body to its connection with the external environment and space. That is why there are so many sections in this discipline. However, one of the youngest, but promising and of particular importance today is genetics. It originated later than the others, but managed to become the most relevant, important and voluminous science, having its own goals, objectives and object of study. Consider what is the history of the development of genetics and what this branch of biology is.

Genetics: subject and object of study

Science received its name only in 1906 at the suggestion of the Englishman Batson. It can be defined as follows: it is a discipline that studies the mechanisms of heredity, its variability in different types of living beings. Consequently, the main goal of genetics is to elucidate the structure of the structures responsible for the transmission of hereditary traits, and to study the very essence of this process.

The objects of study are:

• plants;
• animals;
• bacteria;
• mushrooms;
• Human.

Thus, it covers with attention all the kingdoms of living nature, without forgetting any of the representatives. However, to date, the research of single-celled protozoa is the most focused on the flow of research, all experiments in genetics are carried out on them, as well as on bacteria.

To arrive at the results now available, the history of the development of genetics has come a long and thorny path. In different periods of time, it was subjected to either intensive development or complete oblivion. However, in the end, she nevertheless received a worthy place among the whole family of biological disciplines.

The history of the development of genetics briefly

In order to characterize the main milestones in the formation of the branch of biology under consideration, one should turn to the not so distant past. After all, genetics originates from the 19th century. And the official date of its birth as a completely separate discipline is 1900.

By the way, if we talk about the origins, then we should note the attempts of plant breeding, crossing animals for a very long time. After all, this was done by farmers and pastoralists in the 15th century. It just happened not from a scientific point of view.

The table "History of the development of genetics" will help to master its main historical moments of formation.

Development period	Major discoveries	Scientists
Initial (second half of the 19th century)	Hybridological research in the field of plants (study of generations on the example of a pea species)	Gregory Mendel (1866)
	Discovery of the process of studying sexual reproduction and its significance for fixing and transmitting traits from parents to offspring	Strasburger, Gorozhankin, Hertwig, Van Benevin, Flemming, Chistyakov, Waldeyr and others (1878-1883)
Middle (early-mid XX century)	This is the period of the most intensive growth in the development of genetic research, if we consider the historical era as a whole. A number of discoveries in the field of the cell, its meaning and mechanisms of work, deciphering the structure of DNA, development and crossing, laying all the theoretical foundations of genetics fall precisely on this period of time	Many domestic scientists and geneticists from all over the world: Thomas Morgan, Navashin, Serebryakov, Vavilov, de Vries, Correns, Watson and Crick, Schleiden, Schwann and many others
Modern period (second half of the 20th century to the present day)	This period is characterized by a number of discoveries in the field of microstructures of living beings: a detailed study of the structure of DNA, RNA, protein, enzymes, hormones, and so on. Elucidation of the deep mechanisms of encoding traits and their transmission by inheritance, the genetic code and its decoding, the mechanisms of translation, transcription, replication, and so on. Subsidiary genetic sciences are of great importance, many of which were formed during this period.	V. Elving, Noden and others

In the table above, the history of the development of genetics is briefly displayed. Next, we consider in more detail the main discoveries of different periods.

Major discoveries of the 19th century

The main works of this period were the work of three scientists from different countries:

• in Holland, G. de Vries - the study of the inheritance of traits in hybrids of different generations;
• in Germany, K. Korrens did the same with corn;
• in Austria, K. Chermak - repeated Mendel's experiments on sowing peas.

All these discoveries were based on the works of Gregory Mendel written 35 years earlier, who conducted many years of research and recorded all the results in scientific papers. However, these data did not arouse interest among his contemporaries.

In the same period, the history of the development of genetics includes a number of discoveries on the study of human and animal germ cells. It has been proven that some traits that are inherited are fixed unchanged. Others are individual for each organism and are the result of adaptation to environmental conditions. The work was carried out by Strasburger, Chistyakov, Flemming and many others.

The development of science in the XX century

Since the official date of birth is considered, it is not surprising that it was in the 20th century that the history of the development of genetics was made. research created by this time, allows you to slowly but surely get amazing results.

The creation of the latest advances in technology makes it possible to look into microstructures - this further advances genetics in development. Yes, we have installed:

• structures of DNA and RNA;
• mechanisms of their synthesis and replication;
• protein molecule;
• features of inheritance and consolidation;
• localization of individual traits in chromosomes;
• mutations and their manifestations;
• access to the control of the genetic apparatus of the cell.

Perhaps one of the most important discoveries of this period was the deciphering of DNA. This was done by Watson and Crick in 1953. In 1941, it was proved that signs are encoded in protein molecules. From 1944 to 1970, maximum discoveries were made in the field of the structure, replication and significance of DNA and RNA.

Modern genetics

The history of the development of genetics as a science at the present stage is manifested in the intensification of its various directions. After all, today there are:

• molecular genetics;
• medical;
• population;
• radiation and others.

The second half of the 20th century and the beginning of the 21st century are considered to be the genomic era for the discipline under consideration. After all, modern scientists interfere directly with the entire genetic apparatus of the body, learn to change it in the right direction, control the processes occurring there, reduce pathological manifestations, stop them in the bud.

History of the development of genetics in Russia

In our country, the science in question began its intensive development only in the second half of the 20th century. The thing is that for a long time there was a period of stagnation. These are the reigns of Stalin and Khrushchev. It was during this historical era that a split occurred in scientific circles. T. D. Lysenko, who had power, declared that all research in the field of genetics was invalid. And she herself is not a science at all. Having enlisted the support of Stalin, he sent all the famous geneticists of that time to their deaths. Among them:

• Vavilov;
• Serebrovsky;
• Koltsov;
• Chetverikov and others.

Many were forced to adapt to Lysenko's demands in order to avoid death and continue research. Some emigrated to the US and other countries.

Only after the departure of Khrushchev, genetics in Russia received freedom in development and intensive growth.

Domestic genetic scientists

The most significant discoveries that the science in question can be proud of were those that were realized by our compatriots. The history of the development of genetics in Russia is associated with such names as:

• Nikolay Ivanovich Vavilov (the doctrine of plant immunity, etc.);
• Nikolai Konstantinovich Koltsov (chemical mutagenesis);
• N. V. Timofeev-Resovsky (the founder of radiation genetics);
• V. V. Sakharov (nature of mutations);
• M. E. Lobashev (author of manuals on genetics);
• A. S. Serebrovsky;
• K. A. Timiryazev;
• N. P. Dubinin and many others.

This list can be continued for a long time, because at all times Russian minds were great in all branches and scientific fields of knowledge.

Directions in science: medical genetics

The history of the development of medical genetics originates much earlier than general science. After all, back in the XV-XVIII centuries, the phenomena of inheritance of such diseases as:

• polydactyly;
• hemophilia;
• progressive chorea;
• epilepsy and others.

The negative role of incest in maintaining the health and normal development of offspring was established. Today, this branch of genetics is a very important area of ​​medicine. After all, it is he who allows you to control the manifestations and stop many genetic mutations even at the stage of embryonic development of the fetus.

human genetics

The history of development originates much later than general genetics. After all, it became possible to look inside the chromosome apparatus of people only with the use of the most modern technical devices and research methods.

Man has become an object of genetics primarily from the point of view of medicine. However, the basic mechanisms of inheritance and transmission of traits, their fixation and manifestation in offspring for humans are no different from those in animals. Therefore, it is not necessary to use a person as an object of research.

>Biology abstracts

Genetics

Genetics is one of the most important areas of biology. This is the science of the laws of heredity and variability. The word "genetics" is of Greek origin and means "coming from someone". The objects of research can be plants, animals, people, microorganisms. Genetics is closely related to such sciences as genetic engineering, medicine, microbiology and others.

Initially, genetics was considered as a pattern of heredity and variability based on external and internal signs of an organism. To date, it is known that genes exist and are specially marked sections of DNA or RNA, that is, molecules in which all genetic information is programmed.

Judging by the archaeological evidence, people have known for over 6,000 years that some physical traits can be passed down from generation to generation. Man has even learned to create improved varieties of plants and animal breeds by selecting certain populations and crossing them with each other. However, the importance of genetics became fully known only in the XIX-XX centuries with the advent of modern microscopes. A great contribution to the development of genetics was made by the Austrian monk Gregor Mendel. In 1866 he presented his work on the foundations of modern genetics. He proved that hereditary inclinations do not mix, but are transmitted from generation to generation in the form of separate units. In 1912, the American geneticist Thomas Morgan proved that these units are found in the chromosomes. Since then, classical genetics has taken a scientific step forward and achieved great success in explaining heredity not only at the level of the organism, but also at the level of the gene.

The era of molecular genetics began in the 1940s and 1950s. There is evidence of the leading role of DNA in the transmission of hereditary information. The discovery was the deciphering of the structure of DNA, the triplet code and the description of the mechanisms of protein biosynthesis. Also, the amino acid or nucleotide sequence of DNA and RNA was found.

The first experiments in Russia appeared in the 18th century and were associated with the hybridization of plants. In the 20th century, important work appeared in the field of experimental botany and zoology, as well as at experimental agricultural stations. By the end of the 1930s, a network of organized research institutes, experimental stations, and university departments of genetics appeared in the country. In 1948, genetics was declared a pseudoscience. The restoration of science occurred after the discovery and decoding of the structure of DNA, around the 1960s.

* This work is not a scientific work, is not a final qualifying work and is the result of processing, structuring and formatting the collected information, intended to be used as a source of material for self-preparation of educational work.

Genetics is the science of heredity and variation in organisms. Genetics is a discipline that studies the mechanisms and patterns of heredity and variability of organisms, methods for managing these processes. It is designed to reveal the laws of reproduction of the living by generations, the emergence of new properties in organisms, the laws of individual development of an individual and the material basis of the historical transformations of organisms in the process of evolution. The first two problems are solved by the theory of the gene and the theory of mutations. Elucidation of the essence of reproduction for a particular variety of life forms requires the study of heredity in representatives at different stages of evolutionary development. The objects of genetics are viruses, bacteria, fungi, plants, animals and humans. Against the background of species and other specificity, general laws are found in the phenomena of heredity for all living beings. Their existence shows the unity of the organic world. The history of genetics begins in 1900, when, independently of each other, Correns, Herman and de Vries discovered and formulated the laws of inheritance of traits, when G. Mendel's work Experiments on plant hybrids was republished. Since that time, genetics has gone through three well-defined stages in its development - the era of classical genetics (1900-1930), the era of neoclassicism (1930-1953) and the era of synthetic genetics, which began in 1953. At the first stage, the language of genetics was formed, research methods were developed, fundamental provisions were substantiated, and basic laws were discovered. In the era of neoclassicism, it became possible to intervene in the mechanism of variability, the study of the gene and chromosomes was further developed, the theory of artificial mutagenesis was being developed, which allowed genetics to move from a theoretical discipline to an applied one. A new stage in the development of genetics became possible thanks to the deciphering of the structure of the UzolotoyF DNA molecule in 1953 by J. Watson and F. Crick. Genetics is moving to the molecular level of research. It became possible to decipher the structure of the gene, to determine the material foundations and mechanisms of heredity and variability. Genetics has learned to influence these processes, direct them in the right direction. There are ample opportunities to combine theory and practice. BASIC METHODS OF GENETICS. The main method of genetics for many years is the hybridological method. Hybridization is the process of crossing to produce hybrids. A hybrid is an organism obtained by crossing genetically heterogeneous parental forms. Hybridization can be intraspecific, when individuals of the same species are crossed, and distant, if individuals from different species or genera are crossed. In the study of the inheritance of traits, the methods of monohybrid, dihybrid, polyhybrid crossing are used, which were developed by G. Mendel in his experiments with pea varieties. With monohybrid crossing, inheritance is carried out according to one pair of alternative traits, with dihybrid crossing, by two pairs of alternative traits, and by polyhybrid crossing, by 3.4 or more pairs of alternative traits. When studying the patterns of inheritance of traits and patterns of variability, the method of artificial mutagenesis is widely used, when a change in the genotype is caused with the help of mutagens and the results of this process are studied. The method of artificial production of polyploids has found wide distribution in genetics, which has not only theoretical but also practical significance. Polyploids have a high yield and are less affected by pests and diseases. Biometric methods are widely used in genetics. After all, not only qualitative, but also quantitative ones are inherited and changed. Biometric methods made it possible to substantiate the position of the phenotype and the norm of the reaction. Since 1953, biochemical research methods have acquired special significance for genetics. Genetics came to grips with the study of the material foundations of heredity and variability - genes. Nucleic acids, especially DNA, have become the object of genetics research. The study of the chemical structure of the gene made it possible to answer the main questions posed by genetics. How does trait inheritance work? As a result of which changes in signs occur? Laws of inheritance established by G. Mendel. Dominant and recessive traits, homozygote and heterozygote, phenotype and genotype, allelic traits. Gesh amateur botanist Johann Gregor Mendel owns the discovery of quantitative patterns that accompany the formation of hybrids. In the works of G. Mendel (1856-1863), the foundations of the laws of inheritance of traits were revealed. As the object of research, Mendel chose peas. For the period of research for this strictly self-pollinating plant, a sufficient number of varieties with clearly different studied traits were known. An outstanding achievement of G. Mendel was the development of methods for the study of hybrids. He introduced the concept of monohybrid, dihybrid, polyhybrid crossing. Mendel first realized that only by starting with the simplest case - observing the behavior in the offspring of one pair of alternative traits - and gradually complicating the task. You can understand the patterns of inheritance of traits. Planning the stages of the study, mathematical processing of the data obtained, allowed Mendel to obtain results that formed the basis of fundamental research in the field of heredity. Mendel began with experiments on monohybrid crossing of pea varieties. The study dealt with the inheritance of only one pair of alternative traits (red corolla-AA*white corolla-aa). Based on the data obtained, Mendel introduced the concept of a dominant and recessive trait. He called a dominant trait a trait that passes into hybrid plants completely unchanged or almost unchanged, and recessive one that becomes latent during hybridization. Then Mendel for the first time managed to quantify the frequencies of occurrence of recessive forms among the total number of descendants for cases of mono-, di-, tri-hybrid and more complex crosses. As a result of G. Mendel's research, substantiations of the following generalizations of fundamental importance were obtained: 1. In monohybrid crossing, the phenomenon of dominance is observed. 2. As a result of subsequent crosses of hybrids, the characters are split in a ratio of 3:1. 3. Individuals contain either only dominant, or only recessive, or mixed inclinations. A zygote containing mixed inclinations is called a heterozygote, and an organism that has developed from a heterozygote is called heterozygous. A zygote containing the same (dominant or recessive) inclinations is called a homozygote, and an organism that has developed from a homozygote is called homozygous. Mendel came close to the problems of the relationship between hereditary inclinations and the signs of the organism determined by them. The appearance of the body of envy from a combination of hereditary inclinations. This conclusion was considered by him in the work of the Experiments on plant hybrids. Mendel was the first to clearly formulate the concept of a discrete hereditary inclination, independent in its manifestation from other inclinations. Each gamete carries one deposit. The sum of hereditary inclinations of an organism was, at the suggestion of Johansen in 1909, called the genotype, and the appearance of the organism, determined by the genotype, became known as the phenotype. Johansen later called the hereditary deposit itself the gene. During fertilization, the gametes merge, forming a zygote, while depending on the variety of gametes, the zygote will receive certain hereditary inclinations. Due to the recombination of inclinations during crossings, zygotes are formed that carry a new combination of inclinations, which determines the differences between individuals. This formed the basis of Mendel's fundamental law, the law of gamete frequency. The essence of the law lies in the following provision - the gametes are pure, that is, they contain one hereditary inclination from each pair. A pair of inclinations converging in the gamete was called an allele, and the inclinations themselves were called alleles. Later, the term allelic genes appeared, defining a pair of allelic inclinations. The works of G. Mendel did not receive any recognition in their time and remained unknown until the second rediscovery of the laws of heredity by K. Correns, K. Germak and G. De Vries in 1900. In the same year, Correns formulated three laws of inheritance of traits, which were later called Mendel's laws in honor of the outstanding scientist who laid the foundations of genetics. Monohybrid crossing. Uniformity of hybrids of the first generation. The law of trait splitting. Cytological foundations of uniformity of hybrids of the first generation and splitting of traits in the second generation. Monohybrid crossbreeding is a research method in which the study of one pair of alternative traits is studied. For experiments on monohybrid crossing, Mendel selected 22 cultivars of peas that had clear alternative differences in seven traits: round or angular seeds, yellow or green cotyledons, gray or white seed rind, smooth or wrinkled seeds, yellow or green, axillary or apical flowers, plants are tall or dwarf. For a number of years, Mendel, by self-pollination, selected material for crossing, where the parents were represented by pure lines, that is, they were in a homozygous state. Crossing showed that hybrids show only one trait.

Although the history of genetics began in the 19th century, even ancient people noticed that animals and plants pass on their traits in a number of generations. In other words, it was obvious that heredity exists in nature. In this case, individual signs may change. That is, in addition to heredity, there is variability in nature. Heredity and variability are among the basic properties of living matter. For a long time (until the 19th-20th centuries), the true reason for their existence was hidden from man. This gave rise to a number of hypotheses that can be divided into two types: direct inheritance and indirect inheritance.

Adherents direct inheritance(Hippocrates, Lamarck, Darwin, etc.) assumed that information from each organ and each part of the body of the parent organism is transmitted to the daughter organism through certain substances (gemmules according to Darwin) that are collected in the reproductive products. According to Lamarck, damage or strong development of an organ would be directly transmitted to the next generation. Hypotheses indirect inheritance(Aristotle in the 4th century BC, Weismann in the 19th century) argued that the reproductive products are formed in the body separately and "do not know" about changes in the organs of the body.

In any case, both hypotheses were looking for a "substrate" of heredity and variability.

The history of genetics as a science began with the work of Gregor Mendel (1822-1884), who in the 60s conducted systematic and numerous experiments on peas, established a number of patterns of heredity, and was the first to suggest the organization of hereditary material. The correct choice of the object of study, the characteristics under study, as well as scientific luck allowed him to formulate three laws:

Mendel realized that the hereditary material is discrete, represented by individual inclinations that are transmitted to offspring. In addition, each deposit is responsible for the development of a certain feature of the organism. The sign is provided by a pair of inclinations that came with germ cells from both parents.

At that time, Mendel's scientific discovery was not given much importance. Its laws were rediscovered at the beginning of the 20th century by several scientists on various plants and animals.

In the 1980s, mitosis and meiosis were described, during which chromosomes are regularly distributed between daughter cells. At the beginning of the 20th century, T. Boveri and W. Setton came to the conclusion that the continuity of properties in a number of generations of organisms is determined by the continuity of their chromosomes. That is, by this period of time, the scientific world understood in what structures the “substrate” of heredity lies.

W. Batson was discovered law of gamete purity, and the science of heredity and variability for the first time in history was named by him genetics. V. Johansen introduced into science the concepts (1909), genotype and phenotype. At that time, scientists had already realized that a gene is an elementary hereditary factor. But its chemical nature was not yet known.

In 1906 it was opened gene linkage phenomenon, including sex-linked inheritance of traits. The concept of genotype emphasized that the genes of an organism are not just a set of independent units of heredity, they form a system in which certain dependencies are observed.

In parallel with the study of heredity, the laws of variability were discovered. In 1901, de Vries laid the foundations for the doctrine of mutational variability associated with the occurrence of changes in chromosomes, which leads to changes in traits. A little later, it was discovered that they often occur when exposed to radiation, certain chemicals, etc. Thus, it was proved that chromosomes are not only a “substrate” of heredity, but also variability.

In 1910, largely generalizing earlier discoveries, T. Morgan's group developed chromosome theory:

Genes are located on chromosomes and are arranged linearly there.

Each chromosome has a homologous one.

From each parent, the offspring receives one of each homologous chromosome.

Homologous chromosomes contain the same set of genes, but the alleles of the genes may be different.

Genes on the same chromosome are inherited together() subject to their proximity.

Among other things, at the beginning of the 20th century, extrachromosomal, or cytoplasmic, heredity associated with mitochondria and chloroplasts was discovered.

Chemical analysis of chromosomes showed that they are composed of proteins and nucleic acids. In the first half of the 20th century, many scientists were inclined to believe that proteins are carriers of heredity and variability.

In the 1940s, a leap took place in the history of genetics. Research is moving to the molecular level.

In 1944, it was discovered that such a cell substance as is responsible for hereditary traits. DNA is recognized as the carrier of genetic information. A little later it was stated that one gene codes for one polypeptide.

In 1953, D. Watson and F. Crick deciphered the structure of DNA. It turned out that this double helix made up of nucleotides. They created a spatial model of the DNA molecule.

The following properties were later discovered (60s):

Each amino acid of a polypeptide is encoded by a triplet.(the three nitrogenous bases in DNA).

Each amino acid is encoded by one triplet or more.

Triplets do not overlap.

The reading starts from the starting triplet.

There are no "punctuation marks" in DNA.

In the 70s, another qualitative leap took place in the history of genetics - the development genetic engineering. Scientists begin synthesize genes, change genomes. At this time, actively studied molecular mechanisms underlying various physiological processes.

In the 90s genomes are sequenced(the sequence of nucleotides in DNA is deciphered) of many organisms. In 2003, the human genome sequencing project was completed. There are currently genomic databases. This makes it possible to comprehensively study the physiological characteristics, diseases of humans and other organisms, as well as determine the relationship between species. The latter allowed the systematics of living organisms to reach a new level.

Genetics

The set of alleles for a given organism is called it, and the observable characteristic or trait of the organism is called it. When a given organism is said to be heterozygous for a gene, often one allele is indicated as dominant (dominant), since its qualities predominate in the phenotype of the organism, while other alleles are called recessive, since their qualities may be absent and not observed. Some alleles do not have complete dominance, but instead have incomplete dominance of an intermediate phenotype, or so-called. Both traits are dominant at the same time, and both traits are present in the phenotype.

When a pair of organisms reproduce sexually, their offspring randomly inherit one of the two alleles from each parent.The observation of discrete inheritance and allele segregation is generally known as , or segregation law (the law of uniformity of hybrids of the first generation).

Interaction of several genes

Human height is a complex genetic trait. The results of a study obtained by Francis Galton in 1889 show the relationship between the height of offspring and the average height of their parents.However, the correlation is not absolute and there are significant deviations from genetic variability in the growth of offspring, indicating that the environment is also an important factor in this trait.

Organisms have thousands of genes, and during sexual reproduction, the assortment of these genes is mostly independent, that is, their inheritance occurs randomly with no connection between them. This means that the inheritance of alleles for yellow or green peas has nothing to do with the inheritance of alleles for white or purple flowers. This phenomenon, known as "Law of Independent Succession" (the law of splitting traits), means that the alleles of different genes are mixed between parents to form offspring with different combinations. Some genes cannot be inherited separately, as they are destined for a certain genetic relationship, which is discussed later in the article.

Often different genes can interact in such a way that they affect the same trait. For example, in the spring umbilicus (Omphalodes verna) there is a gene from alleles that determine the color of the flower: blue or purple.However, another gene controls whether or not the flower has the color or is white. When a plant has two copies of the white allele, its flowers are white, regardless of whether the first gene had the blue or purple allele. This interaction between genes is called - the activity of one gene is influenced by variations in other genes.

Many traits are not discrete traits (such as purple or white flowers), but are instead continuous traits (such as human height and skin color).This set of traits is a consequence of the presence of many genes. The influence of these genes is a link between various degrees of environmental influence on organisms. is the degree to which an organism's genes contribute to a set of traits. The measurement of the heredity of traits is relative - in an environment that changes frequently, it has a greater influence on the overall change of characteristic traits. For example, in the United States, human height is a complex trait with an 89% chance of being inherited. However, in Nigeria, where people have a significant difference in access to good nutrition and health care, the probability of inheriting such a trait as growth is only 62%.

Playback

When cells divide, their entire genome is copied, and each daughter cell inherits one complete set of genes. This process is called the simplest form of reproduction and the basis for vegetative (asexual) reproduction. Vegetative reproduction can also occur in multicellular organisms, producing offspring that inherit the genome from the same father. Offspring that are genetically identical to their parents are called clones.

Eukaryotic organisms often use sexual reproduction to produce offspring that have mixed genetic material inherited from two different fathers. The process of sexual reproduction varies (alternates) depending on the type, which contains one copy of the genome ( and a double copy (). Haploid cells are formed as a result of and fusing with another haploid cell genetic material to create a diploid cell with paired chromosomes (for example, fusion (haploid cell) and (haploid cell)) causes the formation. Diploid cells divide by division into haploid cells, without reproducing their DNA, to create daughter cells that randomly inherit one of each pair of chromosomes. Most animals and many plants are diploid organisms for most of his life, with a haploid form, which is characteristic of only one cell - .

Even though they do not use the haploid/diploid mode of sexual reproduction, bacteria have many ways of obtaining new genetic information (i.e. for variability). Some bacteria can pass by passing on a small circular piece of DNA to another bacterium. Bacteria can also take in foreign DNA fragments from the environment and integrate them into their genome, a phenomenon known as transformation. This process is also called - the transfer of fragments of genetic information between organisms that are not related to each other.