Gene is a stretch of a DNA that determines a particular trait. Genes can mutate and take two or more alternative forms, now these are called alleles of a particular gene. Now allele occurs in a fixed spot in a chromosome and in humans we have two sets of chromosomes. hope helps
An allele is a version of a gene. We have two alleles of every gene, located on the same spot on different chromosomes. For example, the gene for eyecolor can either be the allele blue or the allele brown, but they are the same gene!
