Each person has a desire to continue his family and produce healthy offspring. A certain similarity between parents and children is due to heredity. In addition to the obvious external signs of belonging to the same family, the individual development program is also genetically transferred in different conditions.
Heredity - what is it?
This term is defined as the ability of a living organism to maintain and ensure the continuity of its distinctive features and developmental character in subsequent generations. To understand what a person's heredity is, easily by the example of any family. The facial features, physique, appearance in general and the nature of children are always borrowed from one of the parents, grandparents.
Human Genetics
What is the inheritance, features and regularities of this ability is studied by special science. Human genetics is one of its sections. Conditionally it is classified into 2 types. The main types of genetics:
- Anthropological - studies variability and heredity of normal signs of the organism. This section of science is related to evolutionary theory.
- Medical - examines the features of the manifestation and development of pathological signs, the dependence of the occurrence of diseases on environmental conditions and genetic predisposition.
Types of heredity and their characteristics
Information about the specific characteristics of the body is contained in the genes. Biological heredity is differentiated according to their type. Genes are present in cell organelles located in the cytoplasmic space - plasmids, mitochondria, kinetosomes and other structures, and in the chromosomes of the nucleus. On the basis of this, the following types of heredity are distinguished:
- extranuclear or cytoplasmic;
- nuclear or chromosomal.
Cytoplasmic heredity
A characteristic feature of the described type of reproduction of specific features is their transmission on the maternal line. Chromosomal heredity is due mainly to information from the genes of spermatozoa, and extra-nuclear - to the oocyte. It contains more cytoplasm and organelles responsible for the transfer of individual characteristics. This form of predisposition provokes the development of chronic congenital diseases - multiple sclerosis , diabetes mellitus, tunnel vision syndrome and others.
Nuclear heredity
This type of transfer of genetic information is decisive. Often only he is meant, explaining what is human heredity. The chromosomes of the cell contain the maximum amount of data on the properties of the organism and its specific characteristics. Also in them the program of development in certain external conditions of environment is incorporated. Nuclear heredity is the transfer of genes embedded in the DNA molecules that make up the chromosomes. It ensures the continuous continuity of information from generation to generation.
Signs of human heredity
If one of the partners has dark brown eyes, the likelihood of a similar shade of the iris in a child, irrespective of its color in the second parent, is high. This is due to the fact that there are 2 types of heredity: dominant and recessive. In the first case, individual characteristics are predominant. They suppress recessive genes. The second kind of signs of heredity can only appear in the homozygous state. This variant arises if a pair of chromosomes with identical genes is completed in the nucleus of the cell.
Sometimes a child has several recessive symptoms, even if both parents are dominant. For example, a dark-skinned baby with blond curls is born to a swarthy father and mother with dark hair. Such cases clearly demonstrate that such heredity is not just the continuity of genetic information (from parents to children), but the preservation of all signs of a certain kind within the family, including previous generations. The color of eyes, hair and other features can be transmitted even from great-grandmothers and great-grandfathers.
Effect of heredity
Genetics continues to study the dependence of the characteristics of the organism on its innate properties. The role of heredity in the development and state of human health is not always determinative. Scientists distinguish 2 types of genetic traits:
- Rigidly determined - formed before birth, include features of appearance, blood type, temperament and other qualities.
- Relatively deterministic - strongly influenced by the environment, are prone to variability.
Heredity and development
If we are talking about physical indicators, genetics and health have a pronounced relationship. The presence of mutations in chromosomes and serious chronic diseases in the immediate family cause the general state of the human body. External signs completely depend on heredity. Regarding intellectual development and features of nature, the influence of genes is considered relative. Such qualities are more strongly influenced by the external environment than the innate predisposition. In this case, it plays an insignificant role.
Heredity and health
Every future mother knows about the influence of genetic characteristics on the physical development of the child. Immediately after the fertilization of the egg, a new organism begins to form, and heredity plays a decisive role in the appearance of specific features in it. The gene pool is responsible not only for the presence of serious congenital diseases, but also less dangerous problems - predisposition to caries, hair loss, susceptibility to viral pathologies and others. For this reason, at the examination of any doctor the specialist first collects a detailed family anamnesis.
Is it possible to influence heredity?
To answer this question, you can compare the physical performance of several previous and recent generations. Modern youth is much taller, has a stronger physique, good teeth and a high life expectancy. Even such a simplified analysis shows that one can influence heredity. Change the genetic characteristics in terms of intellectual development, character traits and temperament is even easier. This is achieved by improving the environment, correct education and the right atmosphere in the family.
Progressive scientists have long been conducting experiments that assess the impact of medical interventions on the gene pool. In this sphere, impressive results have been achieved, confirming that it is possible to exclude the occurrence of gene mutations at the stage of pregnancy planning , to prevent the development of serious diseases and mental disorders in the fetus. While research is conducted exclusively on animals. To start experiments with the participation of people there are several moral and ethical obstacles:
- Realizing that such heredity, military organizations can use the developed technology for the reproduction of professional soldiers with improved physical abilities and high health indicators.
- Not every family can afford to perform the procedure for artificial insemination of the most complete egg with the highest quality sperm. As a result, beautiful, talented and healthy children will be born only among wealthy people.
- Intervention in the processes of natural selection is practically equivalent to eugenics. Most experts in the field of genetics consider it a crime against humanity.
Heredity and environment
External conditions can significantly affect genetic characteristics. Recent research has shown that a person's heredity depends on such circumstances:
- diet;
- place of residence;
- ecological situation;
- financial condition;
- social status;
- upbringing;
- atmosphere in the family;
- the presence and amount of stress factors;
- Lifestyle;
- emotional background;
- physical activity;
- availability of quality medical care;
- professional activity.