What is the Difference Between Intergenic and Intragenic Interaction

The key difference between intergenic and intragenic interaction is that intergenic interaction occurs when two or more independent genes present on the same or different chromosomes interact to produce phenotypic expression, while intragenic interaction occurs when two alleles on the same gene locus of two homologous chromosomes of a gene interact to produce phenotypic expression.

Gene is the basic unit of heredity. Genes have the genetic information to produce proteins that they code. Therefore, genes decide the genotype and phenotype of an organism. Genetic or gene interactions are different functional associations between genes. These gene interactions can reveal the relationships between genes and pathways. Gene interactions can normally compromise two or more pairs of genes. There are two different types of gene interactions to produce new phenotypic interactions. Two gene interactions are intergenic and intragenic interaction.

CONTENTS

1. Overview and Key Difference
2. What is Intergenic Interaction
3. What is Intragenic Interaction
4. Similarities – Intergenic and Intragenic Interaction
5. Intergenic vs. Intragenic Interaction in Tabular Form
6. FAQ – Intergenic and Intragenic Interaction
7. Summary – Intergenic vs. Intragenic Interaction

What is Intergenic Interaction?

Intergenic interaction is the interaction between two non-allelic genes. These are genes occupying different loci. Therefore, in an intergenic interaction, two or more independent genes present on the same or different chromosomes interact to produce a new phenotype.

Examples of intergenic interaction are epistasis, complementary genes, supplementary genes, duplicate genes, inhibitory genes, and lethal genes. Epistasis is the most well-known example of intergenic interaction. In epistasis, the expression of one gene is masked, inhibited, or suppressed by the expression of one or more other genes.

What is Intragenic Interaction?

Intragenic interaction occurs between the alleles of the same gene. Examples of these types of interactions are co-dominance, incomplete dominance, and multiple alleles. In incomplete dominance, a dominant allele does not entirely hide the effects of a recessive allele. Therefore, the resulting phenotype of the organism shows a blending of both alleles.

In co-dominance, both the alleles of a gene pair in a heterozygote are fully expressed. Because of this, the phenotype of the offspring is a combination of the phenotype of the parents. Furthermore, multiple allelism means within a population there may be three or more alleles for a single gene trait.

What are the Similarities Between Intergenic and Intragenic Interaction?

• Intergenic and intragenic interactions are two different types of gene interactions.
• Both types contribute to genetic diversity.
• They produce different new phenotypes.
• They are post-Mendelian genetics concepts.

What is the Difference Between Intergenic and Intragenic Interaction?

Intergenic interaction occurs when two or more independent genes present on the same or different chromosomes interact to produce phenotypic expression, while intragenic interaction occurs when two alleles on the same gene locus of two homologous chromosomes of a gene interact to produce phenotypic expression. Thus, this is the key difference between intergenic and intragenic interaction. Furthermore, intergenic interaction is also known as inter-allelic interaction, while intragenic gene interaction is also known as intra-allelic interaction.

The infographic below presents the differences between intergenic and intragenic interaction in tabular form for side-by-side comparison.

FAQ: Intergenic and Intragenic Interaction

What is the best example of an intragenic interaction?

Incomplete dominance is the best example of an intragenic interaction in which both alleles of a gene at a locus are partially expressed, resulting in an intermediate or different phenotype.

How do you identify gene interactions?

Gene interactions can be identified by high-throughput methodologies such as the yeast two-hybrid (Y2H), co-immunoprecipitation followed by mass spectrometry, or tandem affinity purification (TAP).

What is epistasis in genetics?

Epistasis refers to the phenomenon of modifying the expression of one gene by masking, inhibiting, or suppressing the expression of one or more other genes.

Summary – Intergenic vs. Intragenic Interaction

Gene interactions are divided into two categories: intergenic and intragenic interaction. Intergenic interaction occurs between two or more independent genes present on the same or different chromosomes in order to produce a particular phenotypic expression. Intragenic interaction occurs between two alleles on the same gene locus on two homologous chromosomes of a gene in order to produce phenotypic expression. Furthermore, examples of intergenic interaction are epistasis, complementary genes, supplementary genes, duplicate genes, inhibitory genes, and lethal genes. On the other hand, examples of intragenic interaction are co-dominance, incomplete dominance, and multiple alleles. So, this summarizes the difference between intergenic and intragenic interaction.

Reference:

1. “Gene Interaction – An Overview.” ScienceDirect Topics.
2. He, Cheng-Qiang, et al. “Intragenic Recombination as a Mechanism of Genetic Diversity in Bluetongue Virus.” Journal of Virology, U.S. National Library of Medicine.

Image Courtesy:

1. “Recessive epistasis and the coat color of golden retrievers” By Vemosca – Own work (CC BY 4.0) via Commons Wikimedia
2. “Incomplete dominance punnett square” By RosendeutschschweizerBlatt.svg: Kilom691derivative work: Adabow – This file was derived from: RosendeutschschweizerBlatt.svg (CC BY-SA 3.0) via Commons Wikimedia