Dominance in genetics is a relationship between alleles of one gene, in which the effect on phenotype of one allele masks the contribution of a second allele at the same locus. The first allele is dominant and the second allele is recessive.For genes on an autosome, the alleles and their associated traits are autosomal dominant or autosomal recessive.
Words like dominant and recessive don’t describe the gene…they describe the trait. What this means is that what a particular version of a gene is actually doing doesn’t matter in terms of the trait being recessive or not. What matters is what trait we are looking at. This can mean that the same version (or allele) of a gene can be dominant, recessive or even co-dominant. It all depends on the trait. As you can see, when talking about dominant and recessive, we need to focus on the trait and not the gene. They describe phenotype not genotype. There are many different genotypes that can make a phenotype. Also, the same genotype can make many different phenotypes. Genoytypes vs Phenotypes. Genetic Traits Earlobes: Free ear lobes (dominant trait) vs. Attached ear lobes (recessive trait). Free earlobes are those that hang below the point of attachment to the head. Attached ear lobes are attached directly to the side of the head. Mendelian Genetics. In heterozygous individuals, the allele that is expressed (seen in individual s appearance) is the dominant allele. The traits that are expressed make up your phenotype. The allele that is not expressed is the recessive allele. They're not necessarily, but they can be. When a recessive trait is more common, it likely because it was advantageous to have that trait so the species evolved to have more of it in the gene pool. Also, since dominant traits are expressed over recessive traits, natural selection has more of an effect on them. If both of these alleles are dominant (homozygous dominant) than the dominant trait is expressed, if one is dominant and one is recessive (heterozygous) than still the dominant trait is expressed. However, if the alleles for both traits are recessive (homozygous recessive) than the recessive trait will be expressed. From Wikipedia, the free encyclopedia. A heterozygote advantage (heterozygous advantage) describes the case in which the heterozygote genotype has a higher relative fitness than either the homozygote dominant or homozygote recessive genotype. A common example is the case where the heterozygote conveys both advantages and disadvantages, while both homozygotes convey a disadvantage. A well-established case of heterozygote advantage is that of the gene involved in sickle cell anaemia. Recessive traits are not favored, and the dominant traits tend to be dominant. That's just a fact. It doesn't mean the recessive traits never surface, and so you do find children of mixed parents with lighter skin, for example.  Neurofibromatosis (NF) is a dominant trait. So only one copy of the mutated gene is needed to have the disorder...for example, if someone with NF marries another person withou … t NF, then the chance that their child would have it is 50%. If both of these alleles are dominant (homozygous dominant) than the dominant trait is expressed, if one is dominant and one is recessive (heterozygous) than still the dominant trait is expressed. However, if the alleles for both traits are recessive (homozygous recessive) than the recessive trait will be expressed. Dominance is not inherent to an allele. It is a relationship between alleles; one allele can be dominant over a second allele, recessive to a third allele, and codominant to a fourth. Also, an allele may be dominant for a particular aspect of phenotype but not for other aspects influenced by the same gene. Dominance differs from epistasis, a relationship in which an allele of one gene affects the expression of another allele at a different gene. Often, the advantages and disadvantages conveyed are rather complicated, because more than one gene may influence a given trait or morph. Major genes almost always have multiple effects (pleiotropism), which can simultaneously convey separate advantageous traits and disadvantageous traits upon the same organism. A common example is the case where the heterozygote conveys both advantages and disadvantages, while both homozygotes convey a disadvantage. A well-established case of heterozygote advantage is that of the gene involved in sickle cell anaemia. Dominance in genetics is a relationship between alleles of one gene, in which the effect on phenotype of one allele masks the contribution of a second allele at the same locus. The first allele is dominant and the second allele is recessive. For genes on an autosome (any chromosome other than a sex chromosome), the alleles and their associated traits are autosomal dominant or autosomal recessive. Dominance is a key concept in Mendelian inheritance and classical genetics. Also, an allele may be dominant for a particular aspect of phenotype but not for other aspects influenced by the same gene. Dominance differs from epistasis, a relationship in which an allele of one gene affects the expression of another allele at a different gene.
http://genetics.thetech.org/ask-a-geneticist/genotype-vs-phenotype http://www.uni.edu/walsh/genetics.html http://www.answers.com/Q/Why_are_recessive_traits_more_common_than_dominant https://en.wikipedia.org/wiki/Heterozygote_advantage http://parablemania.ektopos.com/archives/2007/05/the_genetic_adv.html http://www.answers.com/Q/Why_are_recessive_traits_more_common_than_dominant https://en.wikipedia.org/wiki/Recessive https://en.wikipedia.org/wiki/Heterozygote_advantage https://en.wikipedia.org/wiki/Recessive
what dominant traits are advantageous