The Difference Between Genotype and Phenotype.
Genotype is the genetic constitution of an organism whereas phenotype is the observable characteristics of an organism as a result of genotype and environment. An allele is two or more of the alternative forms of a given genotype that ultimately determines what phenotype is portrayed in the organism.
Recessive and Dominant Alleles
There are 4 important concepts to understand about dominant and recessive alleles. There exists a full spectrum of possible phenotypes between 2 alleles of a genotype. Generally there are 4 types of dominance relationships.
(1) Complete dominance: this occurs when there is complete dominance of the heterozygote phenotype that it cannot be distinguished from the dominant/homozygote parental phenotype
(2) Co-dominance: This occurs when the phenotypic expression of both alleles is clearly and separately seen in the heterozygote offspring. A good example is blood type, where one parent is blood type A and the other parent is blood type B and the offspring is blood type AB
(3) Partial/Incomplete Dominance: There is a degree of dominance to consider in this type of relationship. The dominant allele does not always completely prevent the expression of a recessive one.
(4) Lack of Dominance: A complete lack of dominance can show a full expression of a recessive allele in the phenotype.
Genotype is the genetic constitution of an organism whereas phenotype is the observable characteristics of an organism as a result of genotype and environment. An allele is two or more of the alternative forms of a given genotype that ultimately determines what phenotype is portrayed in the organism.
Recessive and Dominant Alleles
There are 4 important concepts to understand about dominant and recessive alleles. There exists a full spectrum of possible phenotypes between 2 alleles of a genotype. Generally there are 4 types of dominance relationships.
(1) Complete dominance: this occurs when there is complete dominance of the heterozygote phenotype that it cannot be distinguished from the dominant/homozygote parental phenotype
(2) Co-dominance: This occurs when the phenotypic expression of both alleles is clearly and separately seen in the heterozygote offspring. A good example is blood type, where one parent is blood type A and the other parent is blood type B and the offspring is blood type AB
(3) Partial/Incomplete Dominance: There is a degree of dominance to consider in this type of relationship. The dominant allele does not always completely prevent the expression of a recessive one.
(4) Lack of Dominance: A complete lack of dominance can show a full expression of a recessive allele in the phenotype.
Molecular Mechanisms of Gene Action
There are many factors that contribute to the causes of dominance. Sometimes a gene product of RNA synthesis maybe be defective (or just low in activity), for example, when the recessive allele, when homozygous, produces the normal phenotype while the dominant allele may be producing a structural protein incapable of proper function or that it is incapable of function when alongside the recessive allele.
There are many factors that contribute to the causes of dominance. Sometimes a gene product of RNA synthesis maybe be defective (or just low in activity), for example, when the recessive allele, when homozygous, produces the normal phenotype while the dominant allele may be producing a structural protein incapable of proper function or that it is incapable of function when alongside the recessive allele.