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 talk about genetic information, we refer to the set of physical, biochemical and physiological characteristics that individuals of a species transmit to their offspring through the process of inheritance.
This information It is stored in DNA that is inside the nucleus of cells (at least in eukaryotic organisms). It is encoded by a specific sequence of molecules, making up a long string, whose segments are known as genes.
Simplifying a bit: a DNA macromolecule 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, its 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 reproduces, every time a protein is synthesized, every time a hormone is produced. It is the biochemical matrix of our body in which each and every one of its basic and operating aspects are contained.
For this reason, knowledge and manipulation of the genome is such a powerful tool in the hands of human beings: such technology allows us to “correct” the work of nature, to try to find solutions to congenital diseases, design better foods or even program bacteria to manufacture specific compounds.
See also: Genetics
How is genetic information transmitted?
The process of transmitting genetic information from parents to offspring is called inheritance. It can occur in many specific ways, but All types of reproduction involve the passing of genes from one generation of living beings to a new one.
In this process, certain traits can be conserved and others varied, thus arriving at the most effective combination to adapt to the environment and ensure survival. Thus, inheritance depends on the way in which living beings reproduce, which can broadly be understood in two ways: sexual and asexual.
- Asexual reproduction It is the form of reproduction of organisms that do not have a defined sex, that is, whose individuals cannot be distinguished 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 in which sexual living beings reproduce, that is, whose species is made up of females and males. This set of reproduction mechanisms always starts from the production of sexual cells called gametes, in which each individual deposits a random portion of their own genome. As soon as they come into contact, a male and a female gamete fuse (fertilization) and produce one or more new individuals, whose respective genetic information will consist of a random combination of that of their parents. These types of methods have the virtue of not depending exclusively on mutations to incorporate new genetic elements, but by combining the genetic fractions of the parents they allow the introduction of new genes, whether positive or negative for the life of the individual. All individuals born from the same pair of parents, therefore, will have a similar genome.
Types of genetic inheritance
Genetic inheritance, however, occurs according to its own laws according to the mutations and/or alterations of the DNA, in its transition from parents to descendants. From there four types of inheritance emerge:
- Dominant inheritance It is the presence of a dominant gene and a recessive gene in the individual's chromosome pairs, one taken from the father and the other from the mother. The dominant, as its name indicates, always becomes manifest above the recessive, even if the latter does not disappear, and can be transmitted to the offspring.
For example: black eyes are dominant and green eyes are recessive, so the offspring of a mixed pair (one with black eyes and one with green eyes) will have a higher probability of getting black eyes. This is expressed as: dominant + recessive = dominant.
- recessive inheritance We have already seen that there are dominant and recessive characters, and that the former always appear 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 one that overshadows them.
For example: the offspring in the previous example, whose eyes are black but had a green-eyed parent (that is, carries the recessive gene), reproduces with another person whose eyes are green, and surprisingly they have a green-eyed offspring.
How is that possible? Because the new individual obtained the recessive gene for green eyes from its parents, which is percentage-wise less likely, but totally possible. This is expressed as: recessive + recessive = recessive.
- Codominant inheritance In this case, two dominant characteristics from the parents are inherited and manifest, thus producing a mixture or fusion of both traits, without either taking precedence over the other.
For example: a person has blood type A (dominant) and reproduces with another person with blood type B (dominant), and they obtain a descendant who, instead of choosing one of the two dominant traits, obtained both of them. , 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 its 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 black hair color (dominant) reproduces with another with 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 their parents.
Continue with: Genetic code
References
- “Genetic inheritance” on Wikipedia.
- “The flow of genetic information” (video) at the Miguel Hernández University of Elche (Spain).
- “Appendix A. Basic genetic information” in National Center for Biotechnology Information (NCBI).
- “Types of inheritance” in Genetics within everyone's reach.
- “Genetic information” in Austral Valdivia (Chile).
- “Genetic Information” in Lumen Learning.
- “Heredity (genetics)” in The Encyclopaedia Britannica.
