Biology Questions and Answers
- What is polygenic
inheritance? How does it
work?
Polygenic inquantitativeheritance, inheritance, is thalso known ase gene
interactionconditioned by several different genes in which a given trait is (^)
having alleles that may or may not
contribute intensity. The alleles may to increase the phenotypebe
contributing or noncontributing and
there is no dominance amPolygenic inheritance is the type ofong them.
inheritance, and of stature for example, of skin colorin humans.
Considering a given species owhich the length of the individual isf animal i n
conditioned by polygenic inheritance of
three genes, for the genotype havingonly noncontributing alleles (aabbcc) a (^)
basal phenotype, for example, 30 cm,
would emerge. Considerieach contributing allele a ng also t5 cm incrhat forease
in the length of the animal is added, so
in the genotype having only coalleles (AABBCC) the animal wouldntributin g
present the basal phenotype (30 cm)
plus 30 cm mcontributing allele, ore added by eachi.e., its length would (^)
be 60 cm. In the case of triple
heterozygosity, foof the animal would be 45 cm. Tr example, the lengthhat is
the way polygenic inheritance works.
- What is the most probable
inheritance pattern of a trait
with gaussian proportional
distribution of phenotypical
forms?
If a trait statistically has a normal(gaussian, bedistribution of its phenotypicalll-shaped curve) (^) forms it
is probable that it is conditioned by
polygenic ininheritance).heritance (quantitative
In quantitativeseveral genes add to ot inheritance hers makinthe effects ofg it
possible to represent the trait variation
of a given population curve with the heterozygous gein a gaussiannotypes (^)
in the center, i.e., appearing in larger
number, and the homozygous in theextremities.
- How to find the number of
pair of alleles involved in
polygenic inheritance using
the number of phenotypical
forms of the trait they
condition?
Considering “p” the number of
phenotypical foof involved alleles orms and “a” the numberf the polygenic
inheritance. The formula p = 2a + 1 is
then applied.
(Many times it is not possible to
determine preciselyphenotypical forms, p, due to the the number of
multigenic fsince often the observeeature of the inheritance,d variation of
phenotypes seems to be on a continuum
or the trait suffers environmentalinfluence.)
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