alleles

What is an allele?

An allele is a variant form of a gene that arises due to mutations or genetic recombination. Genes are segments of DNA that provide instructions for the development and function of all living organisms. Due to mutations, the sequence of nucleotides (building blocks of DNA) in a gene can be altered, leading to the formation of different alleles. For example, the human gene responsible for determining blood type has three common alleles: A, B, and O.

How do alleles affect traits?

The combination of alleles inherited from both parents determines an individual's genotype, which influences their physical and behavioural traits. In some cases, one allele may be dominant over another, meaning that it masks the effect of the other allele. For example, if an individual inherits one dominant allele for brown eyes and one recessive allele for blue eyes, their eye colour will be brown because the dominant allele is expressed.

In other cases, both alleles may contribute to the phenotype (observable characteristics) in a more complex way. This is called codominance or incomplete dominance. For example, in snapdragons, there are two alleles for flower colour: red and white. If an individual inherits both alleles (one from each parent), they will have pink flowers because both colours are expressed.

Why are alleles important?

Alleles provide genetic diversity within a population and enable organisms to adapt to changing environments over time through natural selection. They also play a crucial role in genetics research by allowing scientists to study patterns of inheritance and trace the evolution of species based on changes in their DNA sequences over time. Additionally, understanding how different alleles contribute to traits can help us develop new treatments for genetic diseases or improve crop yields through selective breeding programs.