The Mendelian Rules

Who was Gregor Mendel?

When the Augustinian monk Gregor Mendel (1822-1884) experimented with peas in the early nineteenth-century Brno monastery garden, he did not suspect the importance of his results.

The Mendelian rules all go back to Gregor Mendel and describe the regularities in simple hereditary traits. While the botanists Correns and de Vries made similar observations on heredity at the beginning of the 20th century, Mendel had already died. So it was only posthumously recognized the importance of his publications and honored his work, at least retroactively.

Today he is considered the founder of classical genetics.

Vocabulary of Classical Genetics

 Phenotype: external appearance of an organism. The appearance is always determined by the genotype

 Genotype: entire genetic makeup of an organism

 Recessive trait: denotes a phenotypically non-occurring trait; but this is still present in the genotype (Xy). In order for it to appear it must be pure (yy)

 Dominant feature: phenotypic feature, occurs in both a homozygous (XX) and mixed (Xy) genotype.

 Allele: refers to the different variants / characteristics of a feature or gene

 Homozygous: both alleles for a given trait are identical (e.g., AA or aa)

 Heterozygous: alleles for a given trait differ (e.g., Ab, Ba)

 Parental generation: Parent generation or initial group of a lineage to be examined

 Branch generation: successor generation of the parental generation

 Monohybrid inheritance: considers only one feature (e.g., color)

 Dihybrian inheritance: considers two features (e.g., color and shape)

Summary

The Augustinian monk Gregor Mendel found common principles of heredity in crossbreeding experiments with peas