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Punnett Square Probability Formula:
Where:
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A Punnett square is a diagram that is used to predict the genotype and phenotype combinations of offspring from parental alleles. It's a fundamental tool in genetics that helps determine the probability of an offspring having particular genotypes.
The basic probability formula used in Punnett squares is:
Where:
Example: For a heterozygous cross (Aa × Aa), the probability of homozygous recessive (aa) is 1/4 or 25%.
Details: Punnett squares help predict inheritance patterns, understand genetic disorders, and calculate the likelihood of specific traits appearing in offspring.
Tips: Enter the number of favorable outcomes (how many squares match your desired genotype/phenotype) and total possible outcomes (usually 4 for monohybrid crosses, 16 for dihybrid). The calculator will compute the probability as a fraction and percentage.
Q1: What's the difference between genotype and phenotype probability?
A: Genotype probability refers to genetic makeup (e.g., AA, Aa, aa), while phenotype probability refers to observable traits (e.g., dominant vs recessive traits).
Q2: How do you count outcomes in dihybrid crosses?
A: For two traits, there are 16 possible combinations (4×4 Punnett square). Count how many squares match your desired combination.
Q3: Can Punnett squares predict complex inheritance?
A: Basic Punnett squares work for simple Mendelian traits. For incomplete dominance, codominance, or polygenic traits, more complex analysis is needed.
Q4: What if the probability comes out to 0?
A: A probability of 0 means the particular genotype or phenotype is impossible given the parental genotypes.
Q5: How accurate are Punnett square predictions?
A: They predict probabilities, not certainties. Actual offspring ratios may vary due to random chance, especially with small sample sizes.