Mendelian genetics

Science

Definition

Mendelian genetics describes the patterns of inheritance first discovered by Gregor Mendel through his experiments with pea plants. It includes the Law of Segregation (each organism has two alleles that separate during gamete formation) and the Law of Independent Assortment (genes on different chromosomes sort independently).

Examples

  • Crossing two heterozygous tall pea plants (Tt × Tt) produces a 3:1 phenotypic ratio of tall to short offspring
  • A dihybrid cross (RrYy × RrYy) yields a 9:3:3:1 phenotypic ratio in the F2 generation
  • Human earlobe attachment (free vs. attached) is often used as a simple example of dominant-recessive inheritance
Key Fact

Monohybrid cross: 3:1 phenotypic ratio; Dihybrid cross: 9:3:3:1 phenotypic ratio in F₂.

Related Terms

Punnett squares Dominant and recessive traits Non-mendelian genetics Meiosis

Study This Concept

Practice Mendelian genetics with free review games in these units:

AP Biology Unit 5: Heredity Biology Unit 3: Genetics and Heredity