The DNA sequence that is responsible for transmitting hereditary traits is called a gene.
The DNA sequence that ensures the transmission of hereditary root traits and characteristics is known as a gene . This structure preserves the inheritance that both women and men (or, failing that, males and females) transmit to their descendants .
The dominant gene is one that is present in a phenotype and that appears twice (when it is made up of a copy corresponding to each of the parents, which is called a homozygous combination ) or in a single dose (called heterozygosity ).
What is a dominant gene
Genetic dominance, therefore, is associated with the link between various alleles of a certain gene physically located in a specific place ( locus ) on a chromosome. Diploid organisms (a group that includes animals as well as plants ) are those that have two sets of chromosomes, respectively inherited from their parents. This means that they have two alleles precisely at each locus. When both alleles of the locus are the same, they are called homozygous, while if they are different, the concept used is heterozygous.
The genotype is the genetic organization of the organism, which influences physical and behavioral traits. The interaction between the two alleles of a heterozygous gene can be dominant or recessive .
The recessive gene is one that, in an allelic pair, cannot manifest itself in the presence of the dominant gene. For this gene to be observed in the phenotype, the organism has to gather two copies of it (that is, one received from the father and the other, of maternal origin).
Eye color and other inherited characteristics depend on dominant genes.
Dominance or recessiveness
The relationship of dominance or recessivity is relative, since there can be more than two variants of a gene (an allele can be recessive with respect to the second allele but dominant with respect to a third ), it always depends on the type of union that is made.
In any case, we can say that the recessive gene cannot manifest itself if its partner is a dominant gene, it will only do so if it joins another recessive gene. This means that if a dominant allele exists within a pair , it will always decide over the recessive one . For example: in eye color we can assign the letter N (dominant) to black and n (recessive) to light blue. If the chromosome that is formed from the union is NN or Nn , the individual will be born with black eyes and only if the union results in nn , will it have light blue eyes.
Dominant gene in humans
In the case of human beings, it is said that we are diploid , which means that we have double genetic information, where one half is a copy of one of the parents and the second of the other, although they are not identical . And here we can clarify that for a dominant gene to be transmitted and manifest, it is enough for one of the parents to have it , while a recessive gene needs to be inherited from both parents .
At this point we return to the example of eye color , and we must say that it is only possible to inherit it if said recessive gene exists in the genetic information of both parents and it manifests itself at the time of chromosome union. It is worth mentioning that, even if we do not have light eyes, we can be carriers of the light eye gene .
It should be noted that there are many diseases that can be inherited genetically , some of them are: Wilson's disease, Hemochromatosis and Hereditary spherocytosis. In order for them to develop, the union that makes them possible must be formed. In some cases they are formed from a dominant gene and in others, a recessive gene; However, it is worth mentioning that if a person suffers from a hereditary disease, even if their children do not manifest it, they will be carriers of it.