Allele vs Trait
In 1822, Mendel observed different forms of hybrids by hybridization of pea plants (Pisum sativum) and the statistical relationship between them. The offspring resulted from hybridization showed interesting clear cut differences in the length of stem, color of seed, shape and color of pod, position, and color of seed. These seven characteristics were called traits.
Through the experiment he had investigated, Mendel concluded that each characteristics of an organism is controlled by a pair of alleles and, if an organism has two different alleles, one may be expressed over the other.
He noticed that there is a “factor” which determines the characteristics (traits) of an individual, and later it was found that factor is the gene.
Gene is a small part of DNA which is located in a specific location of the chromosome, which codes for single RNA or protein. It is the molecular unit of heredity (Wilson and Walker, 2003). Allele is an alternative form of a gene which influences on the phenotypic expression of the gene.
Alleles determine different traits, which carry different phenotypes. As an example, the gene responsible for the flower color of pea plant (Pisum sativum) carries two forms, one allele determines the white color, and the other allele determines the red color. These two phenotypes red and white are not expressed simultaneously in one individual.
In mammals, most genes have two allelic forms. When two alleles are identical, it is called homozygous alleles and, when it is not identical, it is called heterozygous alleles. If alleles are heterozygous, then one phenotype is dominant over other. The allele, which is not dominant, is called recessive. If allelic forms are homozygous, it is symbolized either by RR, if it is dominant, or rr if recessive. If allelic forms are heterozygous, Rr is the symbol.
Although, most of the genes have two alleles in human and produce one characteristic, some characteristics are determined by the interaction of several genes.
When different alleles are in the same site of the genome it is called polymorphism.
The trait is a physical expression of genes such as R gene is responsible for the red color of the flower pea plant (Pisum sativum). Simply it can be explained as the physical characteristics of the genetic determination (Taylor et al, 1998), but traits can be influenced by either environmental factors or both genes and environmental factors.
Combination of different alleles expresses different traits or physical characteristics such as incomplete dominance and codominance.
What is the difference between Allele and Trait?
• Alleles are the alternative form of gene, whereas trait is the physical expression of the gene.
• Allele is in a specific location, in the chromosome, whereas trait is a physical expression.
• Alleles determine the different traits which carry different phenotype.
• Allele may be in homozygous state or heterozygous state, whereas trait does not have such state.
• Allele is a small segment of DNA, whereas trait is a product of biochemical reactions.
• Alleles carry information which is accountable for a trait of an individual, whereas trait is a characteristic of an individual.
Wilson, K., Walker, J., (2003), Practical biochemistry principles and techniques, Cambridge University Press, Cambridge