The genes are made up of two alleles, one from the mother and the other from the father, and they can be dominant or recessive. A dominant allele is one that only needs to occur once to demonstrate the characteristics that it will define.
A recessive allele is one that must occur in pairs to be demonstrated, that is, the father and mother must present the recessive gene for the child to demonstrate a trait considered recessive.
What is the Dominant gene?
They are those that determine visible characteristics. It does not matter if there is a dominant and a recessive allele in the gene, the dominant allele will outnumber the recessive, dominating and, therefore, making the characteristic it possesses visible.
For example, for eye color there are alleles that can determine that eye color is brown (M), this allele is dominant, while for blue eye color (a), we have a recessive allele. Recessive alleles can only be shown if there are two recessive alleles in a gene.
If two brown-eyed parents have children, they will have brown eyes.
| Parents | M | M |
| M | MM | MM |
| M | MM | MM |
If one parent has blue eyes and the other has brown eyes, the children will have brown eyes.
| Parents | M | M |
| to | Ma | Ma |
| TO | Ma | Ma |
Now, if the brown-eyed parent has a recessive allele for blue eyes in his gene and the other has blue eyes, two children are likely to be born with blue eyes, or they will have a two to four chance that their children will have blue eyes:
| Parents | M | to |
| to | Ma | aa |
| to | Ma | aa |
If both parents are brown-eyed but have a recessive allele for blue eyes, only one child will have blue eyes:
| Parents | M | to |
| M | MM | Ma |
| to | Ma | aa |
In the case that both parents have different dominant alleles, their offspring will present new characteristics due to the mixture of alleles.
When there are dominant genes, there is no way for one to overcome the other, therefore, the result will be different. You must remember that a gene is a piece of DNA that stores genetic information. An allele is each different version of the gene for the same type of protein.
For example, the ABO gene is one that synthesizes the proteins that define the human blood group, this gene is made up of three alleles A, B, and O, which define your blood type.
The term allele is an abbreviation of allelomorph, a word is made up of the Greek word allele- , which means “from one to another”, and -morphé, whose meaning is “form”.
What is the Recessive gene?
It is one that has two recessive alleles. Recessive alleles are those that are less likely to determine characteristics, they can only express their characteristics if they bind to another recessive allele.
This means that for recessive alleles to be present, it is necessary that both parents have recessive alleles, even if they do not show them in their characteristics. These alleles or genes are represented by a lowercase letter.
Differences between the dominant gene and recessive gene
- Dominant genes determine the characteristics that the individual will inherit.
- Recessive genes are those that are less likely to occur, both parents must possess them for their offspring to demonstrate the characteristic that they define.
- Recessive alleles are represented by a lowercase letter.
- Dominant genes are capitalized.
- For a dominant gene to be present, it is enough for one parent to possess it.
- For a recessive gene to occur, both parents must possess it.
- Dominant genes are present even in the presence of recessive genes.
- Recessive genes do not appear if there is a dominant gene.
