Biology Questions and Answers
- What is the mathematical
expression of the genetic
equilibrium for genes with two
alleles? Is this statistical
distribution the same as the
statistical distribution of the
respective phenotypes?
Considering p the frequency of one of
the alleles and q the frequency oother allele of a given gene in a f the
population, in this population individuals
produce pfor each q gamete containing gametes with the first allelethe
second allele. Therefore the probabilities
for the first allele of formation of homozyis p^2 , of homozyggous genotypeous^
genotype for the second allele is q^2 and
of the heterozygous genotype is p.q +q.p, i.e., 2p.q.
Since the sum of those probabilitiesnecessarily is 1, the resulting
mathematical expression is: p^2 + 2p.q +
q^2 = 1.
In general the number of genotypicalforms is not identical to the number of (^)
phenotypical forms since there are
dominance anbetween genes that affect thed other interactions
manifestation of the phenotype.
- An hypothesis for the
extinction of the dinosaurs is
that the earth had been hit by
a gigantic meteor that caused
the death of those big reptiles.
In that case the entire genetic
pool of those animals has
been destroyed, invalidating
the Hardy-Weinberg
equilibrium. In Genetics what
is this type of gene frequency
change called?
The phenomenon in which a large
number of genes is destroyeintroduced in a population is calledd or (^)
genetic drift.
When a genetic drift occurs the HardyWeinberg principle is not applicable.
- What are the penetrance
and the expressivity of a
gene?
Individuals that carry a same do not always manifest in an identicalgenotype
manner the correspondent phenotype.These manifestations may differ in
intensity,another, or even the phenotype may n from one individual to (^) ot
manifest in some percentage of carriers.
Gene penetrance is thphenotypical manifestatione percentage o of a gene inf (^)
a given populatio(same genotype). Gene expressivityn of carrier individuals is
the degree (intensity) of the
phenotypical manifeach individual or group of individualsestation of a gene in
that carry the gene (same genotype).
The gene penetrance and the gene
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