Mendel's laws

[men´delz]

in the inheritance of certain traits or characters, offspring are not intermediate in type between the parents, but inherit from one or the other parent in this respect. Thus, if a plant with the factor tallness (TT) is mated with one with the factor shortness (SS), then the offspring will inherit these factors in the ratio TT, 2Ts, SS. This law is usually expressed as the law of independent assortment and the law of segregation.

Mendelian principles

The three “laws” delineated by Gregor Mendel, which form the basis for understanding single trait inheritance.

Mendelian principles
Principle of uniformity in F1
In a mating between a parent with a dominant phenotype (due to homozygosity of an allele) and another parent with a homozygous recessive phenotype controlled by a different allele at the same locus, the progeny will all be genetically heterogeneous and express the dominant phenotype.

Principle of segregation
The principle that holds that alleles separate or segregate at meiosis and are carried in different gametes.

Law of segregation
The principle that holds that allelic pairs of unlinked loci are independently sorted and transmitted to gametes.

Mendel's laws

see MENDELIAN GENETICS.

Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

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References in periodicals archive

Mendel's laws are so effective in resolving questions that had baffled many a great mind before him that there was a powerful temptation to use these same laws to explain any resemblance whatsoever between related persons, including those resemblances that were not considered a priori to have any obvious biological foundation.

From genes for intelligence to our understanding of genes

The science of plant breeding, based on Mendel's laws - selecting desirable plants and crossbreeding them, then selecting and crossing again until the right combination of properties is achieved - is to older methods of plant improvement what a modern computer is to counting on your fingers and toes.

Today's plant breeders increase tomorrow's food supply

"These methods are particularly interesting since they appear to show that genes and chromosomes are not equivalently passed on to the offspring as we always have believed from Mendel's laws of inheritance," Messing says.

A genetic gender gap

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