Types of gene interactions Intragenic V/S Intergenic

These are two types of genetic interactions that affect how traits (like eye colour or height) are shown in a living thing.

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🌱 What is a Genetic Interaction?

Sometimes, how a trait appears depends on how genes work together. When two or more genes affect each other’s activity, we call that a genetic interaction.

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🔍 Let's see the two main types:

🌿 1. Intragenic Interactions (Within One Gene)

• Intra means inside or within.

• So, intragenic interaction happens within a single gene.

• It involves two or more alleles (versions of the same gene).

👇 Example:

Let’s say there is a gene that controls flower colour. It has 3 versions (alleles):

• R (makes red flower),

• r' (makes pale pink),

• r (no colour, white).

Now, if a plant has the combination Rr', it may show a different colour than just red or white, like pink.
This kind of effect is due to how alleles of one gene interact with each other. That’s intragenic.

🧠 Some types of intragenic interactions:

• Incomplete dominance (blending of traits)

• Co-dominance (both traits show up together)

• Multiple alleles (more than two types of alleles)

• Lethal genes (some combinations can be deadly)

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🌾 2. Intergenic Interactions (Between Two or More Different Genes)

• Inter means between.

• So, intergenic interaction happens between two or more different genes.

• These genes may be located on the same or different chromosomes.

👇 Example:

Let’s say two different genes control the shape and colour of seeds.
Gene A affects colour, and Gene B affects shape.
But how colour appears can be affected by the shape gene, and vice versa.
This is intergenic interaction – different genes affecting the same trait or working together.

🧠 Some types of intergenic interactions:

• Epistasis (one gene hides the effect of another gene)

• Complementary genes (two genes work together to show a trait)

• Supplementary genes (one main gene shows the trait, the second helps it)

• Polygenic inheritance (many genes together control one trait, like height or skin colour)

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📊 Main Difference in a Table:

Feature	Intragenic Interaction	Intergenic Interaction
Meaning	Interaction within one gene	Interaction between different genes
Alleles involved	Alleles of the same gene	Alleles of different genes
Number of genes	Only one gene is involved	Two or more genes are involved
Example	Incomplete dominance in flower colour	Epistasis in coat colour of mice
Level of interaction	Inside a gene	Between different genes

🧬 Summary:

• If the interaction is inside one gene, it's called intragenic.

• If the interaction is between different genes, it's called intergenic.

• Both affect how traits are shown, but they work at different levels.