Heredity and Mendel’s laws

In short: Traits are passed from parents to children through genes. Gregor Mendel discovered the basic rules of heredity in the 19th century through crossing experiments with peas.

In more detail: Each gene exists in two variants (alleles), one from each parent (dna-und-gene).

In detail

• Dominant and recessive: A dominant allele prevails, a recessive one shows only if both alleles are recessive.
• Uniformity rule: If pure-bred parents are crossed, all offspring of the first generation are alike.
• Segregation rule: In the second generation traits split in a 3 : 1 ratio.
• Independent assortment: Different traits are inherited independently.
• Genotype and phenotype: Genotype is the genetic makeup, phenotype the visible trait.
• Blood groups: A and B are dominant over O (blut-zusammensetzung-und-aufgaben).
• Limits: Many traits depend on several genes and the environment.
• Meiosis: Alleles are reshuffled in the formation of germ cells (mitose-und-meiose).