What are the Mendelian laws?

Mendel's laws are fundamental laws of heredity (genetics). Inheritance is the transfer of characteristics and characteristics of parents to subsequent generations. The Augustinian priest, teacher and geneticist Johann Gregor Mendel (1822 - 1884) was the first researcher to methodically examine the rules of heredity and is referred to as the "founder of genetics". He was ignorant of the existence of genes and chromosomes. He carried out his experiments on peas and beans. Three laws emerged from his interbreeding experiments published in 1865 under the title "Plant Hybrids Experiments".

of uniformity

If one crosses two individuals of a species that differ in a trait for which they are homozygous, the offspring in the first generation (F1 generation) are equal to each other in terms of this trait.

Example: The eye color brown (B) is dominant over the eye color blue (b). If one parent is brown homozygous for the eye color (BB) and the other parent is blue homozygous for the eye color (bb), one has only offspring with brown eyes in the F1 generation. However, they are brownish for the characteristic eye color brown (Bb).

Merger Act

If one intersects the individuals of the F1 generation, then the individuals of the F2 generation are no longer equal, but split up according to certain numerical ratios. In dominant-recessive inheritance, one obtains a ratio dominant to recessive of 3: 1.

Example: Both parents are brownish-brown for the eye color (Bb). Four children in the F2 generation have three brown eyes, and one blue. A child is brown homozygous for the characteristic of the eye color, two are mixed. The child with the blue eyes is homozygous for the feature of eye color.

independence Act

If one crosses individuals of the same species, which differ in several characteristics in a pure manner, then uniformity and division law apply to each characteristic. In addition to the feature combinations of the parents, new feature combinations occur in the F2 generation.

Small Encyclopedia of Genetics

  • dominant: (Latin rule); feature determinative
  • DNA: deoxyribonucleic acid, storage form of the genetic material
  • Gen: hereditary factor, hereditary
  • heterozygous: mixedbig
  • homozygous: homozygous
  • recessive: (to go back in Latin); inferior to the dominant gene
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