Mendelian Genetics Sandbox

About Mendelian Genetics

Gregor Mendel's experiments with pea plants established the foundation of genetics. When crossing organisms with two genes, each parent contributes one allele from each gene to their offspring.

Punnett Squares

A Punnett square shows all possible combinations of gametes (sex cells) from two parents. For two genes (A and B), each parent can produce four different gamete types, giving 16 possible offspring genotypes.

Epistasis

Epistasis occurs when one gene affects the expression of another. Different types of epistatic interactions produce different phenotypic ratios:

• Independent: Classic 9:3:3:1 ratio - both genes act independently
• Dominant epistasis: 12:3:1 - dominant allele at one locus masks effects of the other
• Recessive epistasis: 9:3:4 - recessive genotype at one locus masks the other (like coat color in mice)
• Duplicate dominant: 15:1 - either dominant allele produces the same phenotype
• Duplicate recessive: 9:7 - both recessive alleles needed for alternative phenotype (like flower color in sweet peas)