Epistasis Punnett Square Calculator

Epistatic Ratios:

\[ 9:3:4 \text{ (Recessive Epistasis)} \] \[ 12:3:1 \text{ (Dominant Epistasis)} \] \[ 9:3:3:1 \text{ (Non-Epistatic Dihybrid)} \]

Parent 1 Genotype:

Parent 2 Genotype:

Epistasis Type:

Phenotypic Ratio:

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1. What is Epistasis?

Epistasis is a genetic phenomenon where the effect of one gene is modified by one or several other genes. It occurs when the expression of one gene depends on the presence of one or more modifier genes.

2. Types of Epistasis

The calculator handles three main types:

Recessive Epistasis (9:3:4 ratio): When homozygous recessive alleles at one locus mask the phenotypic expression of alleles at another locus.
Dominant Epistasis (12:3:1 ratio): When a dominant allele at one locus masks the expression of alleles at another locus.
No Epistasis (9:3:3:1 ratio): Standard dihybrid cross ratio with independent assortment.

3. How the Calculator Works

The calculator:

Determines possible gametes from each parent's genotype
Creates a Punnett square of all possible combinations
Applies epistasis rules to determine phenotypes
Calculates the phenotypic ratio based on the selected epistasis type

4. Using the Calculator

Steps:

Select the genotype for Parent 1 (AABB, AaBB, AABb, or AaBb)
Select the genotype for Parent 2
Choose the type of epistatic interaction
Click "Calculate" to see the expected phenotypic ratio

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between epistasis and dominance?
A: Dominance involves alleles at the same locus, while epistasis involves interaction between alleles at different loci.

Q2: Why are the ratios 9:3:4 and 12:3:1?
A: These ratios result from the masking effect of one gene on another in dihybrid crosses.

Q3: Can I use this for trihybrid crosses?
A: No, this calculator is designed specifically for dihybrid crosses with epistasis.

Q4: What are real-world examples of epistasis?
A: Coat color in labs (B and E loci), albinism, and some human diseases like hereditary deafness.

Q5: How accurate are these ratios in real populations?
A: These are theoretical ratios assuming complete dominance, independent assortment, and no other genetic factors.