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Decoding Genetics: The Punnett Square Calculator

The Punnett Square is a foundational tool in the field of genetics, used to predict the possible genotypes of offspring from a cross between two parents. Our Punnett Square Calculator simplifies this process, allowing students, teachers, and genetics enthusiasts to visualize the outcomes of a monohybrid (single-trait) cross.

🧬 How to Use the Calculator

To generate a Punnett square and see the probable outcomes:

1. Enter Parent 1 Genotype: Input the two-letter genotype for the first parent. Use an uppercase letter for the dominant allele and a lowercase letter for the recessive allele (e.g., 'AA', 'Aa', or 'aa').
2. Enter Parent 2 Genotype: Input the two-letter genotype for the second parent using the same letter.
3. Generate Square: Click the "Generate Punnett Square" button.

The calculator will display a visual Punnett square grid, followed by tables detailing the probable genotype and phenotype ratios and percentages of the offspring. You can also expand the "Calculation Steps" to see a simple breakdown of how the alleles were combined.

Key Genetic Concepts

• Allele: An allele is one of two or more versions of a gene. An individual inherits two alleles for each gene, one from each parent. They are represented by letters (e.g., 'A' and 'a').
• Genotype: This is the genetic makeup of an organism, represented by the combination of alleles (e.g., AA, Aa, aa).
  • Homozygous Dominant (AA): Two dominant alleles.
  • Heterozygous (Aa): One dominant and one recessive allele.
  • Homozygous Recessive (aa): Two recessive alleles.
• Phenotype: This is the observable physical trait of an organism (e.g., flower color, eye color), which is determined by the genotype.
  • Dominant Phenotype: The trait that is expressed when at least one dominant allele is present (in AA or Aa genotypes).
  • Recessive Phenotype: The trait that is only expressed when two recessive alleles are present (in the aa genotype).

💡 Frequently Asked Questions (FAQ)

What is a monohybrid cross?

A monohybrid cross is a genetic mix between two individuals who have homozygous genotypes, or genotypes that have completely dominant or completely recessive alleles, which result in opposite phenotypes for a certain genetic trait.

Why do the letters have to be the same (e.g., 'Aa', not 'Ab')?

This calculator is designed for a monohybrid cross, which examines the inheritance of a single gene. The different letters ('A' vs. 'a') represent different alleles (versions) of that one gene. Using different letters like 'A' and 'B' would imply you are looking at two different genes, which requires a dihybrid cross calculator (a 4x4 grid).

Does this calculator work for co-dominance or incomplete dominance?

This calculator assumes simple Mendelian genetics with complete dominance, where one allele is fully dominant over the other. It does not calculate the results for co-dominance (where both traits are expressed) or incomplete dominance (where a blended phenotype appears).