allelesalternative

An allele is a variant form of a gene. Genes are segments of DNA that code for specific traits. For most genes, there are two or more possible alleles that can exist within a population. These alternative forms arise from mutations in the DNA sequence. For example, a gene that determines eye color might have an allele for brown eyes and an allele for blue eyes.

When an organism inherits genetic material from its parents, it receives two alleles for each gene, one from each parent. These two alleles can be the same (homozygous) or different (heterozygous). The combination of alleles an individual possesses for a particular gene, known as their genotype, determines their phenotype, which is the observable trait.

The concept of alleles is fundamental to understanding Mendelian genetics and the inheritance of traits. Alleles can be dominant or recessive. A dominant allele will express its trait even if only one copy is present, while a recessive allele will only express its trait if two copies are present. The frequencies of different alleles in a population can change over generations due to evolutionary processes like natural selection, genetic drift, and mutation. Studying allele frequencies helps scientists understand genetic diversity and evolutionary history.