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The Epic Interactive Encyclopedia 1998
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Epic Interactive Encyclopedia, The - 1998 Edition (1998)(Epic Marketing).iso
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Monohybrid_inheritance
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1992-09-01
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A pattern of inheritance seen in simple
genetics experiments, where the two animals
(or two plants) being crossed are genetically
identical except for one gene. This gene may
code for some obvious external features such
as seed colour, with one parent having green
seeds and the other having yellow seeds. The
offspring are monohybrids, that is, hybrids
for one gene only, having received one copy
of the gene from each parent. Known as the F1
generation, they are all identical, and
usually resemble one parent, whose version of
the gene (the dominant allele) masks the
effect of the other version (the recessive
allele). Although the characteristic coded
for by the recessive allele (for example,
green seeds) completely disappears in this
generation, it can reappear in offspring of
the next generation if they have two
recessive alleles. On average, this will
occur in one out of four offspring from a
cross between two of the monohybrids. The
next generation (called F2) show a 3:1 ratio
for the characteristic in question, 75% being
like the original parent with the recessive
allele. Gregor Mendel first carried out
experiments of this type (crossing varieties
of artificial y bred plants, such as peas)
and they revealed the principles of genetics.
The same basic mechanism underlies all
inheritance, but in most plants and animals
there are so many genetic differences
interacting to produce the external
appearance (phenotype) that such simple,
clear-cut patterns of inheritance are not
evident. Monophysite Greek `one-nature' a
member of a group of Christian heretics of
the 5th-7th centuries who taught that Jesus
had one nature, in opposition to the orthodox
doctrine (laid down at the Council of
Chalcedon in 451) that he had two natures,
the human and the divine. Monophysitism
developed as a reaction to Nestorianism and
led to the formal secession of the Coptic and
Armenian churches from the rest of the
Christian church. Monophysites survive today
in Armenia, Syria, and Egypt.