How did Mendel discover the principles of inheritance through his experiments with pea plants?

SouravNovember 8, 2024

Answer

Gregor Mendel, often referred to as the father of genetics, discovered the principles of inheritance through meticulous experiments with pea plants (Pisum sativum) conducted between 1857 and 1864. His pioneering work laid the foundation for modern genetics, although it went largely unrecognized during his lifetime.

Experimental Design

Mendel chose pea plants for several reasons:

• Self-fertilization: Pea plants naturally self-pollinate, which allowed him to control breeding by transferring pollen manually.
• Distinct traits: He selected varieties with clear, contrasting characteristics such as seed shape (round vs. wrinkled), flower color (purple vs. white), and plant height (tall vs. short).
• Rapid generation time: The annual life cycle of pea plants enabled Mendel to observe multiple generations in a relatively short period .

Mendel began his experiments by establishing pure-breeding lines for each trait. He ensured that these plants consistently produced offspring identical to themselves through self-fertilization. Once he had pure lines, he cross-pollinated different varieties and recorded the traits of the resulting offspring.

Key Findings

Mendel’s experiments led to three fundamental principles of inheritance:

1. Law of Segregation: This principle states that each individual carries two alleles for each trait, but only one allele is passed on to the offspring during gamete formation. Mendel observed that traits segregated independently during the formation of gametes, resulting in a 3:1 ratio of dominant to recessive traits in the second generation (F2) when he allowed the first generation (F1) hybrids to self-fertilize .
2. Law of Independent Assortment: Mendel found that the inheritance of one trait did not affect the inheritance of another trait. This means that different traits are passed on independently from one another, which was demonstrated through dihybrid crosses involving two traits at once .
3. Law of Dominance: In cases where two different alleles are present, one allele may dominate over the other, masking its expression in the phenotype. For example, when Mendel crossed tall and short pea plants, all F1 offspring were tall, demonstrating that the tall trait was dominant over the short trait