Dihybrid Cross Calculator - Punnett Square

Looking for a comprehensive dihybrid cross calculator? Look no further! Our tool computes inheritance probabilities for two traits and four alleles simultaneously, offering a larger version of the traditional Punnett square Calculator. 

With this tool, you can determine both phenotypic and genotypic ratios, while also gaining insights into genetic square construction and inheritance rules.

How to do a dihybrid cross?

Let's imagine we want to determine the probability of a child having green eyes and curly hair. The child's mother is a blonde with curly hair, while the father has light, straight hair.

Let's consider two different traits:

• Trait A - eye color; 
• Trait B - hair type.

How are they inherited? Both traits are autosomal - located on chromosomes 1-22. For simplicity, let's assume that curly and dark hair are dominant traits with single genes controlling them.

Our alleles:

• A - curly hair (dominant); 
• a - straight hair (recessive); 
• B - dark hair (dominant); 
• b - light hair (recessive).

What are the possible sets of alleles?

The mother is heterozygous for curly hair (A, a) and homozygous recessive for hair color (b, b). Her possible allele combinations are: Ab, ab.

The father is homozygous recessive for both traits (a, a, b, b), so he produces one allele combination: ab.

Now let's create the Punnett square for two traits. The size of the square for a dihybrid cross should be 4x4.

Here's the Punnett square table:

Now that you've constructed the Punnett square, you're ready to interpret the results! You can find the dihybrid cross ratio in the section below.

Genotype and phenotype ratios

Let's delve into the genotype and phenotype ratios.

Starting with the genotypic ratio, we can either manually count the combinations in the Punnett square or utilize our handy dihybrid cross calculator. In our previous example, it's straightforward: half of the Punnett square consists of the Aabb combination, and the remaining half is aabb.

So, the genotypic ratio is a simple 0.5:0.5, which simplifies to 1:1.

Now, onto the phenotypic ratio:

• Phenotype for Aabb: Ab
• Phenotype for aabb: ab

Remarkably, the phenotypic ratio aligns with the genotypic ratio, yielding a balanced 1:1 distribution.

In essence, half of the offspring will inherit alleles Ab, resulting in curly, blond hair, while the other half will possess alleles ab, leading to straight, blond hair. 👱‍♀️👱

For those craving precision, our dihybrid cross calculator offers detailed percentages for various allele sets. To derive the genotypic ratio, divide all values by the smallest percentage, yielding the simplest integers. For instance:

6.25 : 12.5 : 6.25 : 12.5 : 25 : 12.5 : 6.25 : 12.5 : 6.25

With 6.25 as the smallest figure, dividing all values by it results in:

1 : 2 : 1 : 2 : 4 : 2 : 1 : 2 : 1

There you have it – a clear genotypic ratio at your fingertips.

FAQ

What's the significance of dihybrid crosses in genetics?

• Dihybrid crosses help unravel complex inheritance patterns involving two different traits, offering insights into genetic diversity and inheritance probabilities.

Can dihybrid crosses predict traits accurately?

• While dihybrid crosses provide probabilities, factors like genetic recombination and environmental influences can affect trait expression, making predictions less deterministic.

Are dihybrid crosses only relevant in plants and animals?

• No, dihybrid crosses are applicable across various organisms, including humans. They contribute to understanding inheritance patterns and genetic diversity in diverse populations.

How to do Punnett squares with 2 traits?

• To create a Punnett square for two traits, first, identify the alleles for each trait in the parent organisms. Then, list the possible gametes (sperm and egg cells) that each parent can produce along the top and left side of the square. Once you have the gametes listed, fill in the square with combinations of these gametes to predict the genotypes of the offspring. Finally, determine the phenotypic ratios by analyzing the genotypes in the Punnett square.

What's the probability of inheritance of both homozygous-recessive traits?

• The probability of inheriting both homozygous-recessive traits depends on the genetic makeup of the parents. If both parents are homozygous recessive (aa) for both traits, then all offspring will inherit two recessive alleles for each trait. In such cases, the probability of inheriting both homozygous-recessive traits is 100%. However, if only one parent is homozygous recessive for both traits, the probability depends on the other parent's genotype and follows Mendelian inheritance patterns.

What are the heterozygous genotypes?

• Heterozygous genotypes contain one dominant allele and one recessive allele for a particular trait. In a dihybrid cross involving two traits (A and B), heterozygous genotypes are represented by individuals with genotypes like AaBb, where 'Aa' represents one dominant and one recessive allele for trait A, and 'Bb' represents one dominant and one recessive allele for trait B. These heterozygous individuals may exhibit the dominant phenotype for one or both traits, depending on the dominance relationships between the alleles.

Enjoy your use. 😊