How do traits get expressed?

The gene is the section or part of DNA that carries information for a protein. This information is translated to synthesize protein (enzymes, hormones or proteins).

Therefore, each trait is the result of the biochemical reaction of this expressed form of a gene (protein). 

The gene that is responsible for the functionality of an organism in the presence of an alternate form of a gene is known as a dominant gene. The trait expressed by this dominant gene is known as a dominant trait.

The gene that expressed only in the presence of another identical gene is known as recessive gene and the trait expressed is a recessive trait. 

For example, When the Pure tall pea plant (TT) is crossed with the dwarf (tt) pea plant, the trait expressed will be Tt, which will produce a tall pea plant.