mendel's law

2 definitions found

mendel's law - Collaborative International Dictionary of English v.0.48 :

  Mendel's law \Men"del's law\
     A principle governing the inheritance of many characters in
     animals and plants, discovered by Gregor J. Mendel (Austrian
     Augustinian abbot, 1822-84) in breeding experiments with
     peas. He showed that the height, color, and other characters
     depend on the presence of determinating factors behaving as
     units. In any given germ cell each of these is either present
     or absent.
  
     Note: The following example (using letters as symbols of the
           determining factors and hence also of the individuals
           possessing them) shows the operation of the law:
           Tallness being due to a factor T, a tall plant, arising
           by the union in fertilization of two germ cells both
           bearing this factor, is TT; a dwarf, being without T,
           is tt. Crossing these, crossbreeds, Tt, result (called
           generation F1). In the formation of the germ cells of
           these crossbreeds a process of segregation occurs such
           that germ cells, whether male or female, are produced
           of two kinds, T and t, in equal numbers. The T cells
           bear the factor "tallness," the t cells are devoid of
           it. The offspring, generation F2, which arise from the
           chance union of these germ cells in pairs, according to
           the law of probability, are therefore on an average in
           the following proportions: 1 TT : 2 Tt : 1 tt; and thus
           plants pure in tallness (TT) and dwarfness (tt), as
           well as crossbreeds (Tt), are formed by the
           interbreeding of crossbreeds. Frequently, as in this
           example, owning to what is called the dominance of a
           factor, the operation of Mendel's law may be
           complicated by the fact that when a dominant factor (as
           T) occurs with its allelomorph (as t), called
           recessive, in the crossbreed Tt, the individual Tt is
           itself indistinguishable from the pure form TT.
           Generation F1, containing only the Tt form, consists
           entirely of dominants (tall plants) and generation F2
           consists of three dominants (2 Tt, 1 TT) to one dwarf
           (tt), which, displaying the feature suppressed in F1,
           is called recessive. Such qualitative and numerical
           regularity has been proved to exist in regard to very
           diverse qualities or characters which compose living
           things, both wild and domesticated, such as colors of
           flowers, of hair or eyes, patterns, structure, chemical
           composition, and power of resisting certain diseases.
           The diversity of forms produced in crossbreeding by
           horticulturists and fanciers generally results from a
           process of analytical variation or recombination of the
           factors composing the parental types. Purity of type
           consequently acquires a specific meaning. An individual
           is pure in respect of a given character when it results
           from the union of two sexual cells both bearing that
           character, or both without it.
           [Webster 1913 Suppl.]

mendel's law - WordNet (r) 2.1 (2005) :

  Mendel's law
      n 1: (genetics) one of two principles of heredity formulated by
           Gregor Mendel on the basis of his experiments with plants;
           the principles were limited and modified by subsequent
           genetic research