We explain what genetic information is, where it is stored and how it is transmitted. Also, types of genetic inheritance.
What is genetic information?
In biology, when we speak of genetic information, we refer to the set of physical, biochemical and physiological characteristics that individuals of a species transmitted to their offspring, through the process of inheritance.
This information is stored in the DNA what's inside the core of the cells (at least in organisms eukaryotes). It is encoded by a specific sequence of molecules, composing a long string, whose segments are known as genes.
Simplifying a bit: a macromolecule DNA is made up of a long string of smaller molecules in a very specific order, and each significant segment of that long string is a gene. In turn, each gene encodes a specific aspect of the characteristics of the Living being, that is, of your genetic information.
During the embryonic process the body of a living being is formed following the plans established in said genetic information, that is, what we call genotype. Each individual has a unique genotype, but tremendously similar to that of the other members of its species (and more or less similar to that of other neighboring species, that is, evolutionarily close).
At the same time, genetic information comes into play every time one of our cells is play, each time a protein, every time a hormone is produced. It is the biochemical matrix of our body, in which each and every one of its basic and functional aspects are contained.
Thats why he knowledge and the manipulation of the genome is such a powerful tool in the hands of the human being: similar technology allows us to "correct" the work of the nature, to try to find a solution to congenital diseases, design better food or even schedule bacteria to make compounds specific.
How is genetic information transmitted?
The process of transmission of genetic information from parents Descendants are called inheritance. It can occur in many specific ways, but all types of reproduction involve the passing of genes from one generation of living things to a new one.
In this process, certain traits can be preserved and others varied, thus arriving at the most effective combination for adapt to the environment and ensure survival. Thus, heredity depends on the way in which living beings reproduce, which can be broadly understood in two ways: sexual and asexual.
- Asexual reproduction. It is the way of reproduction of the organisms that do not have a defined sex, that is, whose individuals do not distinguish between male and female. The set of asexual reproduction mechanisms allows the DNA of the parent to be copied and transmitted identically to the offspring, creating genetically exact copies of itself (clones). Eventually, the genetic material undergoes modifications during this process (mutations), which can give rise to new adaptations (positive mutations) or can prevent the new individual from living (negative mutations).
- Sexual reproduction. This is the way we reproduce sexed living beings, that is, whose species is made up of females and males. This set of reproduction mechanisms always starts from the production of sex cells called gametes, in which each individual deposits a portion, at random, of their own genome. As soon as they come into contact, a male and female gamete fuse (fertilization) and produce one or more new individuals, whose respective genetic information will consist of a random combination of those of their parents. These types of methods have the virtue not depending exclusively on mutations to incorporate new genetic elements, but rather by combining the genetic fractions of the parents allow the introduction of new genes, whether positive or negative for the life of the individual. All individuals born to the same pair of parents, therefore, will have a similar genome.
Types of genetic inheritance
However, genetic inheritance occurs according to its own laws according to mutations and / or alterations of DNA, in its transit from parents to descendants. From there four types of inheritance follow:
- Dominant inheritance. It is the presence of a dominant and a recessive gene in the pairs chromosomal of the individual, taken one from the father and the other from the mother. The dominant, as its name indicates, is always manifest above the recessive, although the latter does not disappear, and can be transmitted to the offspring.
For example: black eyes are dominant and green eyes are recessive, so that the offspring of a mixed couple (one with black eyes and the other with green eyes) will have a greater probability to take out the black eyes. This is expressed as: dominant + recessive = dominant.
- Recessive inheritance. We have already seen that there are dominant characters and other recessive ones, and that the former always manifest themselves above the latter, without the latter being completely lost. Well, recessive characters can also be inherited and become manifest, as long as there is no dominant that overshadows them.
For example: the offspring of the previous example, whose eyes are black but had a green-eyed parent (that is, they carry the recessive gene), reproduces with another person whose eyes are green, and they surprisingly have a green-eyed offspring.
How is that possible? Because the new individual got the recessive gene for green eyes from their parents, which is percentage less likely, but totally possible. This is expressed as: recessive + recessive = recessive.
- Codominant inheritance. In this case, two dominant characters are inherited and manifested from the parents, thus producing a mixture or fusion of both traits, without any one depriving above the other.
For example: a person has a blood type A (dominant) and reproduces with another person of blood type B (dominant), and they obtain a descendant who, instead of opting for one of the two dominant traits, obtained both , being his blood type AB.
- Intermediate inheritance. Also known as incomplete or partial dominance, it occurs when an individual inherits both a dominant and a recessive trait from their parents, but instead of the former prevailing, a manifest fusion of both genes is obtained, that is, an intermediate state.
For example: an individual with color of black hair (dominant) reproduces with another of yellow hair color (recessive), and its descendant, instead of inheriting the dominant black hair, obtains brown hair, whose color expresses the mixture of both color traits of its parents .