🧬 Genetics & Cellular Biology

Punnett Square Calculator

Q: What is the expected phenotypic ratio in a heterozygous monohybrid cross?

In a simple Mendelian cross between two heterozygous parents (Aa × Aa), the expected phenotypic ratio is 3:1 (75% dominant phenotype, 25% recessive phenotype), while the genotypic ratio is 1:2:1 (25% AA, 50% Aa, 25% aa).

Q: What is a dihybrid cross?

A dihybrid cross is a breeding experiment between two organisms that are identically hybrid for two distinct traits governed by two separate genes (e.g. AaBb × AaBb). It generates a 4x4 Punnett grid of 16 boxes with a classic 9:3:3:1 phenotypic ratio.

Simulate genetic inheritance with interactive 2×2 monohybrid and 4×4 dihybrid crosses. Calculate exact genotypic and phenotypic probability ratios.

Presets:

Parental Genotypes

Parent 1 Genotype (Maternal)

2 letters (e.g. Aa, AA, aa)

Parent 2 Genotype (Paternal)

2 letters (e.g. Aa, AA, aa)

🔲 Punnett Square Offspring Table

Genotypic Ratio

Phenotypic Ratio

What is a Punnett Square?

Invented by English geneticist Reginald C. Punnett in 1905, the Punnett Square is a square diagram that is used to predict the genotypes of a particular cross or breeding experiment. It visually displays all possible combinations of maternal alleles with paternal alleles to determine the statistical probabilities of offspring traits.

Mendel’s Laws of Inheritance

Law of Segregation: During gamete formation, the two alleles for each gene segregate from each other so that each gamete carries only one allele for each gene.
Law of Independent Assortment: Genes for different traits can segregate independently during the formation of gametes, forming the basis for the 9:3:3:1 ratio in dihybrid crosses.

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Punnett Square Calculator

Parental Genotypes

🔲 Punnett Square Offspring Table

What is a Punnett Square?

Mendel’s Laws of Inheritance

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