Genetics

Drag-and-Drop Di-hybrid Punnett Square  |  Explore key inheritance concepts

Chapter Summary

Learn Mendelian inheritance from mono- to trihybrid crosses, Punnett squares, pedigrees, sex-linked traits, dominance patterns, Hardy–Weinberg, and speciation.

Interactive Di-hybrid Cross (AaBb × AaBb)

Drag the four gametes from each parent into the slots below:

Parent 1 Gametes:
AB
Ab
aB
ab
Parent 2 Gametes:
AB
Ab
aB
ab
Drop Parent 1 gametes here →
Drop Parent 2 gametes here ↓

Sickle Cell Anemia

Caused by a point mutation in β-globin gene: Glu→Val at position 6. Heterozygotes (HbA/HbS) have some protection against malaria (“balanced polymorphism”).

Trihybrid Crosses & Probability

Three genes assort independently. Probability of a specific genotype = product of individual probabilities (e.g. 3/4 × 3/4 × 3/4 = 27/64 for all dominant traits).

Pedigree Analysis

Pedigree example

Use symbols to track inheritance patterns across generations.

Sex-Linked Traits & Dominance

  • Complete Dominance: one allele masks another (e.g. Pp).
  • Partial Dominance: heterozygote shows intermediate phenotype (e.g. red/white snapdragon → pink).
  • X-Linked Recessive: more common in males (e.g. color blindness, hemophilia).

Key Terms

Quiz Yourself

1. In a dihybrid cross AaBb × AaBb, what % of offspring are A_B_?