What is the Difference Between Dominant and Recessive Genes

The main difference between dominant and recessive genes is that the dominant genes always express the dominant trait whereas the recessive genes express the recessive trait. Furthermore, the dominant genes are more likely to pass to the future generation while the recessive allele is less likely to pass to the future generation.

Dominant and recessive genes are the two forms of genes classified based on the ability to express over the other gene. Genes/factors which determine a particular character always occur in pairs. The three possible gene pairs are the homozygous dominant (AA), homozygous recessive (aa), and the heterozygous (Aa) pairs.

Key Areas Covered

1. What are Dominant Genes
     – Definition, Expression, Features
2. What are Recessive Genes
     – Definition, Expression, Features
3. What are the Similarities Between Dominant and Recessive Genes
     – Outline of Common Features
4. What is the Difference Between Dominant and Recessive Genes
     – Comparison of Key Differences

Key Terms

Dominant Genes, Dominant Trait, Mendelian Genetics, Recessive Genes, Recessive Trait

What are Dominant Genes

Dominant genes are the genes that always express the dominant trait. They are designated in capital letters. The expression of the dominant trait occurs when two dominant genes occur in the gene pair (homozygous dominant) and when only one dominant gene occurs in the gene pair while the other gene is recessive ( heterozygous). Therefore, the dominant gene masks the effect of the recessive gene in the heterozygous condition. Moreover, it has no effect from the recessive gene for the expression of the dominant trait. An example of a dominant trait is the red color flowers in pea.

Figure 1: Inheritance of Dominant Genes

Here, the reason behind the expression of the dominant trait by dominant genes is the ability of dominant genes to produce the complete polypeptide through gene expression. Only the complete polypeptide can produce the dominant trait.

What are Recessive Genes

Recessive genes are the genes that are unable to express the dominant trait. Hence, recessive traits are the traits produced by the recessive genes. Recessive genes are designated by the small letters. In the heterozygous condition, the dominant gene masks the effect of the recessive gene. Therefore, only the dominant trait is expressed under the complete dominance conditions as described by Mendelian genetics. However, in situations with non-Mendelian genetics including incomplete dominance, co-dominance, multiple traits, sex-linked traits, etc. the masking of the expression of the recessive trait occurs in different ways.

Figure 2: Masking the Effect of Recessive Genes by Dominant Genes

Furthermore, the main reason behind the expression of the recessive trait in the homozygous recessive condition is the inability of recessive genes to express the complete polypeptide during gene expression. Therefore, there will be no trait for that character, which can be characterized by the presence of white color in the pea flower.

Similarities Between Dominant and Recessive Genes

• First, dominant and recessive genes are the two types of factors responsible for the determination of a trait.
• Moreover, both types of genes can cause genetic diseases.

Difference Between Dominant and Recessive Genes

Definition

Dominant genes refer to the genes responsible for the expression of the dominant character while the recessive genes refer to the genes responsible for the expression of the recessive character.

Expression

Therefore, the main difference between dominant and recessive genes is that dominant genes always express the dominant trait while recessive genes express the recessive trait.

Examples

An example of a dominant trait is the red color flowers in pea while its recessive trait is the white color flowers.

Polypeptide

One other difference between dominant and recessive genes is that the dominant genes produce the complete polypeptide while the recessive genes produce an incomplete polypeptide.

Masking the Effect

Moreover, the dominant genes mask the effect of the recessive genes while the recessive genes are unable to mast the effect of the dominant genes. Hence, this is another difference between dominant and recessive genes.

Similar Genes

Additionally, dominant genes do not require the presence of a similar gene in the gene pair for the expression while recessive genes require the presence of a similar gene in the gene pair for their effect.

Inheritance

An important difference between dominant and recessive genes is that the dominant genes are more likely to be inherited while recessive genes are less likely to be inherited.

Formation of Diseases

Another important difference between dominant and recessive genes is that dominant genes are more prone to produce diseases while recessive genes are less prone to produce diseases.

Conclusion

In conclusion, dominant genes are the genes that can express the dominant trait in the gene pair. Also, they can completely mask the effect of the recessive genes in the heterozygous condition. On the other hand, recessive genes cannot express a trait. Therefore, the main difference between dominant and recessive genes is the ability to produce a trait.

Reference:

1. “What Are Dominant and Recessive?” Learn.Genetics, Genetic Science Learning Center| University of Utah, Available Here

Image Courtesy:

1. “Punnett square mendel flowers” By Madprime – Own work (CC BY-SA 3.0) via Commons Wikimedia  
2. “Mendelian inheritance” By Benutzer:Magnus Manske – http://de.wikipedia.org/wiki/Datei:Mendelian_inheritance_3_1.png (Public Domain) via Commons Wikimedia