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Alleles may be represented by a pair of letters: one letter denoting the allele donated by one parent and a second letter indicating the allele contributed by the other parent. If both alleles from both parents are identical, the animal has a homozygous genotype with two identical alleles at this locus (for example, AA or aa), but if they are different, then the individual is heterozygous (Aa or aA). When one of the alleles in a heterozygote completely determines the phenotype even when the second allele is present, the suppressing allele is said to be dominant and the suppressed allele is recessive. This phenomenon is called complete dominance. The completely dominant allele is designated by a capital letter (A), and the corresponding recessive allele is designated by a lowercase letter (a). In this scenario, the individual with the genotype “AA” has the same phenotype as individual with the genotype “Aa”—the recessive gene is hidden. But, while it doesn’t “show” in the individual, it could emerge as observable in offspring. This plays an important role in the probabilities of the inheritance of any trait.