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 shape it:
-Alelo is a neologism that was created in the 20th century and that 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 defined 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 alelomorph : that which can appear in different forms. In the field of biology, the value adopted by each allele is called gen which, in a pair, occupies the same space in chromosomes that are homologous.
Recessive , on the other hand, is an adjective that in the biology It applies to hereditary characteristics that are not expressed in the phenotype of the one who has them, although they can manifest themselves in the descendants of the individual in question.
Understanding what a recessive allele 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 from the expression of the phenotype of the other allele (the recessive allele).
The recessive allele, in this way, is the one whose expression of the phenotype 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 with lowercase and dominant with uppercase.
To manifest, recessive alleles must appear in loneliness . Suppose that, in a flower, the yellow color is a recessive allele. Thus, in order for the flower to determine its yellow color, it must have only the alleles that express this hue. In the case of dominant alleles, on the other hand, they are imposed by appearing in single or double doses and thus manage to express their characteristics .
When we talk about human beings, we have to state that it is determined that each gene has two alleles: one that comes from the father and one that comes from the mother. Starting from this we find the fact that it is said that the allele that comes to establish that the son has brown eyes is dominant, however, that of the blue eyes is recessive.
That means that if the couple is made up of a father and a mother with brown eyes, their baby will have them brown. In the event that one of the two has them blue, it is most likely that the child also has them brown for the dominant allele, unless he inherits the recessive alleles of other relatives.