Mendelism
Original Article by: Michael R. Cummings, Department of Biological Sciences, University of Illinois, Chicago, Illinois.
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Key Concepts
• Gregor Johann Mendel, an Augustinian monk, formulated the
fundamental principles governing the transmission of genetic
traits. The term Mendelism describes these basic laws of ge-
netic inheritance.
• Mendel's work, which has been confirmed by genetic crosses
and breeding applications with many different organisms,
is regarded as the beginning of genetics as an organized scien-
tific discipline.
• Mendel proposed that each plant (the organism that he
studied) contains a pair of factors (genes) for each trait.
The trait that is expressed in the first filial generation (F1) is
controlled by a dominant factor, whereas the unexpressed trait
is controlled by a recessive factor.
• The most simple Mendelian cross, called a monohybrid cross,
involves only one pair of traits. A cross that involves two pairs
of contrasting traits is known as a dihybrid cross.
• Mendel postulated that factors (genes) separate or segregate
from each other during gamete (sex cell) formation.
• The traits of offspring are determined by segregation,
independent assortment, and random fertilization.
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Fig. 1: Schematic representation of a monohybrid cross. Pure-bred yellow
and green pea strains are crossed and yield a typical 3:1 ratio (3 yellow and 1
green) in the F2 generation. Y and y represent the yellow and green factors
(genes), respectively. P represents the parent generation, F1 represents the
first filial generation, and F2 represents the second filial generation. (Copyright
© McGraw Hill's)
Fundamental principles governing the transmission of
genetic traits, as discovered by Gregor Mendel. Mendelism is
the term used to describe the basic laws of genetic inheritance
(Fig. 1). These operating laws were formulated by Gregor
Johann Mendel (1822–1884), an Augustinian monk, who
conducted a number of notable experiments on plant hybrids.
Mendel published his scientific work in 1866; however, it went
largely unheralded until 1900, when other investigators
performed similar hybridization experiments and brought his
work to the attention of the scientific world. The rediscovery
of his work is regarded as the beginning of genetics as an
organized discipline. Since then, genetic crosses and breeding
endeavors with many different organisms have confirmed the
fundamental nature and significance of Mendel's work.
