Difference between Monohybrid and Dihybrid

Genetics is a branch of biology that studies the inheritance of the physical and physiological characteristics of living beings. One of the fundamental concepts in genetics are the terms monohybrid and dihybrid, which refer to the way in which characters are inherited from parents to their children.

Monohybrid

The term monohybrid refers to an organism that has a single characteristic or hereditary trait that differentiates its parents. This means that the parents who begot him differ from each other in a single character. An example of this is eye color, where one parent has brown eyes and the other has blue eyes. In this case, the child will be a monohybrid and will have eyes of a single color, inheriting only one of the two alleles that control the eye color variant.

Example of Monohybrid Crossing

If we cross two pea plants that differ in their ability to produce yellow or green seeds, this is an example of a monohybrid cross. In this case, the inheritance of a single character from parents to children is shown according to the following scheme:

• Parent 1: AA (yellow seeds)
• Parent 2: aa (green seeds)
• Son: Aa (yellow seeds)

It is important to note that allele A is dominant over allele a, so although the child has only one allele A, it is expressed in the phenotype of yellow seeds.

Dihybrid

The term dihybrid refers to an organism that has two characteristics or hereditary traits that differentiate its parents. This means that the parents who generated it differ from each other in two characters. An example of this is eye color and height, where one parent has brown eyes and is tall, and the other has blue eyes and is short. In this case, the child will eventually present eyes of a single color and a certain height, inheriting an allele from each of the parents in both characters.

Example of Dihybrid Crossing

If we cross two pea plants that differ in their ability to produce yellow or green and smooth or wrinkled seeds, this is an example of a dihybrid crossing. In this case, the inheritance of two characters from parents to children is shown according to the following scheme:

• Parent 1: AaBb (yellow, smooth seeds)
• Parent 2: aabb (green, wrinkled seeds)
• Son: AaBb (smooth yellow seeds)

In this case, it is important to highlight that both alleles A and B are dominant over a and b, respectively, so the son presents the phenotype of yellow and smooth seeds, although he inherits one allele from each parent in both characters.

Conclusions

In summary, the fundamental difference between a monohybrid and a dihybrid lies in the number of characters or traits that they inherit from parents to their children. A monohybrid inherits a single discrepant character between both parents, while a dihybrid inherits two discrepant characters between them. This difference is reflected in Mendelian inheritance patterns and allows us to understand the genetic basis of variability in biological populations.