Alleles and genes

A gene is a stretch of DNA or RNA that determines a certain trait. Genes mutate and can take two or more alternative forms- an allele is one of these forms of a gene. For example, the gene for eye color has several variations (or alleles) such as an allele for blue eye color or an allele for brown eyes.

An allele is found at a fixed spot on a chromosome. Chromosomes occur in pairs so organisms have two alleles for each gene — one allele in each chromosome in the pair. Since each chromosome in the pair comes from a different parent, organisms inherit one allele from each parent for each gene. The two alleles inherited from parents may be same (homozygous) or different (heterozygotes).

• To sum it all up: 
• an allele is a specific variation of a gene. We have two alleles of every gene, located on the same spot on different chromosomes. For example, the gene for eye color can either be the allele blue or the allele brown, but they are the same gene! 
• and a gene is a section of DNA that controls a certain trait and can be translated into a protein