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If overdominance is the main cause for the fitness advantages of heterosis, then there should be an over-expression of certain genes in the heterozygous offspring compared to the homozygous parents. On the other hand, if dominance is the cause, fewer genes should be under-expressed in the heterozygous offspring compared to the parents.
In medical genetics, compound heterozygosity is the condition of having two or more heterogeneous recessive alleles at a particular locus that can cause genetic disease in a heterozygous state; that is, an organism is a compound heterozygote when it has two recessive alleles for the same gene, but with those two alleles being different from each other (for example, both alleles might be ...
If the alleles are different, the genotype is referred to as heterozygous. Genotype contributes to phenotype , the observable traits and characteristics in an individual or organism. [ 3 ] The degree to which genotype affects phenotype depends on the trait.
Hogenauer, et al. [17] have challenged this popular theory with a human study. Prior data were based solely on mouse experiments. These authors found the heterozygote state was indistinguishable from the noncarrier state. Another theory for the prevalence of the CF mutation is that it provides resistance to tuberculosis. Tuberculosis was ...
Overdominance is a phenomenon in genetics where the phenotype of the heterozygote lies outside the phenotypical range of both homozygous parents. Overdominance can also be described as heterozygote advantage regulated by a single genomic locus, wherein heterozygous individuals have a higher fitness than homozygous individuals.
Segregation and independent assortment are consistent with the chromosome theory of inheritance. When the parents are homozygous for two different genetic traits (llSS and LL s P s P), their children in the F 1 generation are heterozygous at both loci and only show the dominant phenotypes (Ll S s P).
In heterozygote advantage, or heterotic balancing selection, an individual who is heterozygous at a particular gene locus has a greater fitness than a homozygous individual. Polymorphisms maintained by this mechanism are balanced polymorphisms. [4]
The words homozygous, heterozygous, and hemizygous are used to describe the genotype of a diploid organism at a single locus on the DNA. Homozygous describes a genotype consisting of two identical alleles at a given locus, heterozygous describes a genotype consisting of two different alleles at a locus, hemizygous describes a genotype consisting of only a single copy of a particular gene in an ...