recessive allele

In order to know the meaning of the term recessive allele, the first thing we have to do is proceed to discover the etymological origin of the two words that give it its shape:
-Alelo is a neologism that was created in the twentieth century and comes from the Greek. Specifically, it derives from “allello” and means “two”.
-Recessive, on the other hand, is a word of Latin origin that is the result of the sum of three clearly delimited components: the prefix “re-”, which means “backwards”; "Cessus", which can be translated as "walked" and the suffix "-ivo", which is used to indicate active or passive relationship.

The notion of allele comes from allelomorph: what can appear in different forms. In the field of biology, the value adopted by each gene which, in a pair, occupies the same space on chromosomes that are homologous.

Recessive, for its part, is an adjective that in the biology applies to hereditary characteristics that are not expressed in the phenotype of the one who has them, although they can be manifested in the descendants of the individual in question.

Understanding what a recessive allele is leads us to the notion of dominant allele and, above all, what is known as dominance. The alleles that make up the same gene are related to each other: dominance is the masking that one allele (the dominant allele) achieves of the expression of the phenotype of the other allele (the recessive allele).

The recessive allele, thus, is one whose phenotype expression is masked. It should be noted that being dominant or recessive is relative: in a gene with three alleles, for example, one allele can be recessive with respect to another and dominant over the third.

Recessive alleles are represented in lower case and dominant alleles in upper case.

To manifest, recessive alleles must appear in loneliness. Suppose that, in a flower, the color yellow is a recessive allele. Thus, for the flower to be able to determine its yellow color, it must have only the alleles that express that hue. In the case of dominant alleles, on the other hand, they prevail by appearing in single or double doses and thus manage to express their features.

When we talk about human beings, we have to state that each gene is determined to have two alleles: one that comes from the father and the other that comes from the mother. Starting from this, we find the fact that it is said that the allele that establishes that the child has brown eyes is dominant, however, the one with blue eyes is recessive.

This means that if the couple is made up of a brown-eyed mother and father, their baby will have brown eyes. In the event that one of the two has blue, it is most likely that the little one also has brown because of the dominant allele, unless he inherits the recessive alleles from other relatives.