Sex Chromosomes and Sex Determination. Sex Determination in Honeybees. Test Crosses. Biological Complexity and Integrative Levels of Organization. Genetics of Dog Breeding. Human Evolutionary Tree. Mendelian Ratios and Lethal Genes.
Environmental Influences on Gene Expression. Epistasis: Gene Interaction and Phenotype Effects. Genetic Dominance: Genotype-Phenotype Relationships. Phenotype Variability: Penetrance and Expressivity.
Citation: Miko, I. Nature Education 1 1 Why can you possess traits neither of your parents have? The relationship of genotype to phenotype is rarely as simple as the dominant and recessive patterns described by Mendel. Aa Aa Aa. Complete versus Partial Dominance. Figure 1. Figure Detail. Multiple Alleles and Dominance Series. Summarizing the Role of Dominance and Recessivity.
References and Recommended Reading Keeton, W. Heredity 35 , 85—98 Parsons, P. Nature , 7—12 link to article Stratton, F. Article History Close. Share Cancel. Revoke Cancel. Keywords Keywords for this Article. Save Cancel. Flag Inappropriate The Content is: Objectionable. Flag Content Cancel. Email your Friend. Submit Cancel. This content is currently under construction. Explore This Subject. Gene Linkage. The Foundation of Inheritance Studies. Methods for Studying Inheritance Patterns.
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Featured Content. Introduction to Genomics. Polygenic Risk Scores. For every gene, you inherit two alleles: one from your biological father and one from your biological mother.
Together, these alleles are called a genotype. If the two versions are different, you have a heterozygous genotype for that gene. For example, being heterozygous for hair color could mean you have one allele for red hair and one allele for brown hair.
The relationship between the two alleles affects which traits are expressed. It means your biological parents contributed identical variants. In this scenario, you may have two normal alleles or two mutated alleles. Mutated alleles can result in a disease and will be discussed later. This also affects which characteristics appear.
In a heterozygous genotype, the two different alleles interact with each other. This determines how their traits are expressed. Commonly, this interaction is based on dominance. Depending on how the dominant and recessive genes interact, a heterozygous genotype might involve:. In complete dominance, the dominant allele completely covers up the recessive one.
One example is eye color , which is controlled by several genes. The allele for brown eyes is dominant to the one for blue eyes. However, you still have the recessive allele for blue eyes. Instead, they blend together, which creates a third trait. This type of dominance is often seen in hair texture.
The waviness is a combination of curly and straight hair. Codominance happens when the two alleles are represented at the same time. Both traits are equally expressed.
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