What are some examples of alleles?

1 Answer
May 23, 2015

Alleles are different forms of the same gene. Mendel studied seven traits in pea plants that each had two alleles, one dominant and one recessive. Generally, the dominant allele is represented by a capital letter, and a recessive allele is represented by the same letter, but in lowercase, such as R and r.

An example of alleles for flower color in pea plants are the dominant purple allele, and the recessive white allele; for height they are the dominant tall allele and recessive short allele; for pea color, they are the dominant yellow allele and recessive green allele.



Not all traits are governed by dominant and recessive alleles. Sometimes they show incomplete dominance, in which the presence of the two different alleles produces a blending of the two phenotypes (expressions of a trait. An example of incomplete dominance includes the flower color of snap dragons. If a plant inherits two red alleles, the flowers will be red; if it inherits two white alleles, the flowers will be white; and if it inherits one red allele and one white allele, the flowers will be pink.

There are other types of inheritance, all involving the inheritance of alleles of various traits. In humans, every trait is governed by the inheritance of alleles, such as height, skin color, eye color, hair color, blood type, hemoglobin structure, and even whether or not you secrete the enzyme amylase in your saliva, or can taste or smell certain substances. Many traits are governed by not just one set of alleles, but many sets of alleles even on different chromosomes. The field of genetics is very interesting and exciting.