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How did Gregor Mendel’s pea plant experiments help establish genetics?

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Diagram of a DNA double helix showing its twisted ladder structure, with a close-up of the sugar-phosphate backbone, paired nitrogenous bases (adenine, thymine, cytosine, guanine), and labeled nucleotides and hydrogen bonds. — human genome The human genome is made up of approximately three billion base pairs of deoxyribonucleic acid (DNA). The bases of DNA are adenine (A), thymine (T), guanine (G), and cytosine (C).

Gregor Mendel’s experiments with garden peas were foundational to the science of genetics because they shifted the study of heredity from speculation to a rigorous, mathematical experimental framework.12

By performing controlled cross-pollination of pure-breeding pea lines, Mendel observed consistent numerical ratios in offspring, such as the 3:1 ratio in the second generation (F2). These results led him to deduce several key principles:1

Discrete Units: He identified that traits are determined by discrete hereditary units, now known as genes, which exist in pairs.13
Law of Segregation: He proposed that these paired units separate during the formation of gametes, ensuring each parent contributes one allele to their offspring.13
Law of Dominance: He observed that some alleles exert greater influence than others, masking the expression of recessive traits.13
Law of Independent Assortment: Through experiments involving multiple traits, he concluded that different gene pairs are inherited independently of one another.13

Mendel’s methodology established a prototype for scientific inquiry that remains essential for understanding Mendelian inheritance and modern genetic discovery.1