Basic Concepts of Genetics: Mendel's Laws
Understanding how traits are inherited from one generation to the next
Historical Background
Johann Gregor Mendel (1822–1884), often called the "father of genetics," was an Austrian monk who conducted groundbreaking hybridization experiments with garden peas (Pisum sativum).
Between 1856 and 1863, Mendel cultivated and tested approximately 28,000 pea plants, carefully tracking how traits like seed color, seed shape, and flower color were passed from parents to offspring.
His work was largely unrecognized during his lifetime but was rediscovered in the early 1900s, establishing the foundation for the modern science of genetics.
Key Definitions
Gene
A discrete unit of hereditary information located on a chromosome. Genes carry the instructions for building proteins that determine traits.
Alleles
Different versions of the same gene. Genes are transferred from parents to offspring in pairs known as alleles. When alleles are the same → homozygous; when different → heterozygous.
Dominant vs. Recessive
In a heterozygote, the dominant allele (uppercase, e.g., A) masks the expression of the recessive allele (lowercase, e.g., a).