1. The dominant gene It is the prevailing expression of an allele in relation to another contrasting one on the homologous chromosome, that is, an inherited genetic characteristic that manifests itself in a superior way in the organism.
1. The recessive gene it is the expression of a characteristic that occurs when it is present equally in both homologous chromosomes, that is, when the alleles received are both recessive.
Etymology:Gen, by German geneon the Greek γένος (genos), from ‘lineage’, ‘origin’, ‘race’. + Dominant, by the Latin forms domĭnans, domĭnantisconfigured from the verb dominariand the suffix -nte, reflected in -ns, -ntisaccording to deverbal adjectives.+ Recessive, for German recessivewith reference in Latin recessusparticiple of I will recedefrom ‘to go back’, accompanied by the suffix -ivo, seen in German -ivwith respect to Latin -ivusaccording to the noun.
Grammatical category: Dec. 2022.
in syllables: gen + do-mi-nan-te / re-ce-si-vo.
Dominant and Recessive Gene
A dominant gene It is one that expresses its information even though a different form of the gene is present on the homologous chromosome. The dominant gene always determines the physical characteristic that the individual will display.
Genes contain all the information to create a new individual.
The physical characteristics that an individual will have, whether animal or plant, is what is known as phenotype. In the case of humans, the phenotype corresponds to skin color, hair color, eye color, height, earlobe shape, nose shape, etc. The phenotype is what the individual looks like on the outside..
He genotype It is the constitution of the individual from the point of view of its genetics, corresponds to all the information found in your DNA and that it was inherited from their parents. The genotype largely determines the phenotype, however sometimes the phenotype is expressed or not depending on characteristics of the environment.
An example of this corresponds to diseases, a person daughter of one or both diabetic parents has a hereditary tendency to suffer from the disease, however if you adopt a healthy lifestyle, carry out regular physical activity, limit your intake of carbohydrates and If you maintain your weight within the normal range, it is very likely that you will not develop the disease even if you are predisposed to it.
Dominant genes and recessive genes
The information contained in the DNA is organized in chromosomes, these in turn contain fragments with specific information called genes that are located in certain places on the chromosome called loci, each gene is related to a quality of the individual. Genes located on the X and Y sex chromosomes transmit sex-linked characteristics.
When individuals reproduce, they contribute half of their genetic information to the new being. This occurs since the chromosomes are found in pairs. During reproduction the pairs separate to form gametes or reproductive cells, which are the eggs and sperm. At the time of separation, the chromosomes are located randomly, so the genetic information is different between these cells.
Once the chromosomes are reunited in pairs to form the new individual, it happens that there may be different information from each parent about the same trait. Let’s take eye color as an example, if you receive the gene from the father for the color blue and the gene from the mother for the color brown, it will happen that the dominant gene will be expressed, which in this case is brown eyes. From the phenotype point of view, the new being will have brown eyes, but its genotype has information for brown eyes and blue eyes.
This way when there are two genes for the same information, there will be one that will have the ability to hide the other and express itself, it is the dominant gene. The gene that is hidden is called a recessive gene. When two identical genes are inherited, we speak of a homozygous constitution, which can be dominant if two dominant genes are inherited or recessive if two recessive genes are inherited, in the event that two different genes are inherited, one dominant and the other recessive, it occurs. the heterozygous constitution. For an individual to express a recessive trait, it is necessary that they have a homozygous recessive genetic constitution.
In the case of genes located on the X chromosome, they will always be expressed in the male sex since it contains only one chromosome of this type. This explains why inherited disorders such as hemophilia and color blindness are more common in men, due to the fact that the genes that transmit these diseases are located on the X chromosome.
Photos: iStock – jian wang / Christopher Futcher