Gregor Mendel The Grandfather of Genetics Mendel Modern

Gregor Mendel The Grandfather of Genetics

Mendel Modern genetics had its beginnings in an abbey garden, where a monk named Gregor Mendel documented a particulate mechanism of inheritance. n He discovered the basic principles of heredity by breeding garden peas in carefully planned experiments. n His approach to science had been influenced at the University of Vienna by one of his professors: the physicist Doppler. n

Mendel’s work n In order to study inheritance, Mendel chose to use peas, probably as they are available in many varieties. n The use of plants also allowed strict control over the mating. n He chose to study only characters that varied in an ‘either-or’ rather than a ‘more-or-less’ manner.

Genetic crosses To hybridise 2 varieties of pea plants, Mendel used an artist’s brush. n He transferred pollen from a true breeding white flower to the carpel of a true breeding purple flower. n

Tracking heritable characteristics n Mendel tracked heritable characters for 3 generations. n When F 1 hybrids were allowed to selfpollinate a 3: 1 ratio of the 2 varieties occurred in the F 2 generation.

Mendel’s law of segregation By carrying out these monohybrid crosses, Mendel determined that the 2 alleles for each character segregate during gamete production. n Mendel discovered this c. 1860. n DNA was not discovered until 1953. n

Mendel’s terminology n n n True breeding: When the plants self-pollinate, all their offspring are of the same variety. Hybridisation: Mating, or crossing, of two varieties. Monohybrid cross: A cross that tracks the inheritance of a single character. P generation: True breeding parents. F 1 generation: (first filial) Hybrid offspring of the P generation. F 2 generation: (second filial) Offspring from the self-fertilisation of the F 1 hybrids.

Mendel’s impact n Mendel’s theories of inheritance, first discovered in garden peas, are equally valid for figs, flies, fish, birds and human beings. n Mendel’s impact endures, not only on genetics, but on all of science, as a case study of the power of hypothesis/deductive thinking.

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