What are the Dominant and Recessive Traits?
One of the most important principles that governs life is inheritance of genes. There are over 200 traits that are transmitted from generation to generation in humans. These interesting aspects of human genetics are known as hereditary traits. These hereditary traits include the dominant and recessive traits in humans. Most of the genes are transmitted in the Mendelian pattern and a few are transmitted through the non-Mendelian pattern that includes: co-dominance, sex-linked genes and polygenes.
The physical traits are those that are expressed and what makes every individual an 'individual'. These genes reside on specific segments of the DNA. Each gene is grouped to form a chromosome and each chromosome is found in the nucleus of the cell. There are two copies of each gene present in an individual's body with the exception of eggs and sperms. These two gene copies include one copy of the gene from the mother and one copy from the father. Thus, we see some of our physical traits are similar to our mother and some match our father's traits.
There are two or more variations in most of the genes called alleles. An individual can inherit same pair of alleles or two different pairs of alleles. When there are two different alleles, they are expressed in a different way. The trait that is expressed in case of two different alleles, gives rise to the dominant and recessive traits. When a dominant allele is present, it is always observed that the dominant trait is expressed. The recessive trait is observed only in case there are two recessive alleles present.
It is generally believed that the dominant alleles are the most common traits observed in a population. However, this is not a complete fact. Many times the alleles may be dominant, but the allele for expression of a trait may be recessive. Thus, many times the dominant trait is not expressed in an individual. Let me explain this inheritance pattern in the following examples.
